INTERRUP.

Interrupt List Release 61 Last change 16jul00
Copyright (c) 1989-1999,2000 Ralf Brown

Index for category B - BIOS

05 - INT 05 - PRINT SCREEN

INT 05 - PRINT SCREEN
Desc:	dump the current text screen to the first printer
Notes:	normally invoked by the INT 09 handler when PrtSc key is pressed, but
	  may be invoked directly by applications
	byte at 0050h:0000h contains status used by default handler
	  00h not active
	  01h PrtSc in progress
	  FFh last PrtSc encountered error
	default handler is at F000h:FF54h in IBM PC and 100%-compatible BIOSes
	since the BOUND instruction also calls INT 05h, but returns control
	  to the BOUND instruction, a failed BOUND check will cause an infinite
	  loop of PrtScreens unless the INT 05 handler is aware of the problem
	  and checks whether the interrupt was invoked by a BOUND instruction
BUG:	some old BIOSes/applications appear to destroy BP on return
SeeAlso: INT 10/AH=12h/BL=20h,INT 4A"Tandy 2000",INT 5E"TI Professional"
SeeAlso: INT 80"Phar Lap"

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11 - INT 11 - BIOS - GET EQUIPMENT LIST

INT 11 - BIOS - GET EQUIPMENT LIST
Return: (E)AX = BIOS equipment list word (see #00226,#03215 at INT 4B"Tandy")
Note:	since older BIOSes do not know of the existence of EAX, the high word
	  of EAX should be cleared before this call if any of the high bits
	  will be tested
SeeAlso: INT 4B"Tandy 2000",MEM 0040h:0010h

Bitfields for BIOS equipment list:
Bit(s)	Description	(Table 00226)
 0	floppy disk(s) installed (number specified by bits 7-6)
 1	80x87 coprocessor installed
 3-2	number of 16K banks of RAM on motherboard (PC only)
	number of 64K banks of RAM on motherboard (XT only)
 2	pointing device installed (PS)
 3	unused (PS)
 5-4	initial video mode
	00 EGA, VGA, or PGA
	01 40x25 color
	10 80x25 color
	11 80x25 monochrome
 7-6	number of floppies installed less 1 (if bit 0 set)
 8	DMA support installed (PCjr, Tandy 1400LT)
	DMA support *not* installed (Tandy 1000's)
 11-9	number of serial ports installed
 12	game port installed
 13	serial printer attached (PCjr)
	internal modem installed (PC/Convertible)
 15-14	number of parallel ports installed
---Compaq, Dell, and many other 386/486 machines--
 23	page tables set so that Weitek coprocessor addressable in real mode
 24	Weitek math coprocessor present
---Compaq Systempro---
 25	internal DMA parallel port available
 26	IRQ for internal DMA parallel port (if bit 25 set)
	0 = IRQ5
	1 = IRQ7
 28-27	parallel port DMA channel
	00 DMA channel 0
	01 DMA channel 0 ???
	10 reserved
	11 DMA channel 3
Notes:	Some implementations of Remote (Initial) Program Loader (RPL/RIPL)
	  don't set bit 0 to indicate a "virtual" floppy drive, although the
	  RPL requires access to its memory image through a faked drive A:.
	  This may have caused problems with releases of DOS 3.3x and earlier,
	  which assumed A: and B: to be invalid drives then and would discard
	  any attempts to access these drives.	Implementations of RPL should
	  set bit 0 to indicate a "virtual" floppy.
	The IBM PC DOS 3.3x-2000 IBMBIO.COM contains two occurences of code
	  sequences like:
	    INT 11h
	    JMP SHORT skip
	    DB 52h,50h,53h; "RPS"
	    skip: OR AX,1
	    TEST AX,1
	  While at the first glance this seems to be a bug since it just
	  wastes memory and the condition is always true, this could well be
	  a signature for an applyable patch to stop it from forcing AX bit 0
	  to be always on. MS-DOS IO.SYS does not contain these signatures,
	  however.
BUGs:	Some old BIOSes didn't properly report the count of floppy drives
	  installed to the system.  In newer systems INT 13h/AH=15h can be
	  used to retrieve the number of floppy drives installed.
	Award BIOS v4.50G and v4.51PG erroneously set bit 0 even if there are
	  no floppy drives installed; use two calls to INT 13/AH=15h to
	  determine whether any floppies are actually installed
SeeAlso: INT 12"BIOS",#03215 at INT 4B"Tandy 2000"

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12 - INT 12 - BIOS - GET MEMORY SIZE

INT 12 - BIOS - GET MEMORY SIZE
Return: AX = kilobytes of contiguous memory starting at absolute address 00000h
Note:	this call returns the contents of the word at 0040h:0013h; in PC and
	  XT, this value is set from the switches on the motherboard
SeeAlso: INT 11"BIOS",INT 2F/AX=4A06h,INT 4C"Tandy 2000",MEM 0040h:0013h

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1300 - INT 13 - DISK - RESET DISK SYSTEM

INT 13 - DISK - RESET DISK SYSTEM
	AH = 00h
	DL = drive (if bit 7 is set both hard disks and floppy disks reset)
Return: AH = status (see #00234)
	CF clear if successful (returned AH=00h)
	CF set on error
Note:	forces controller to recalibrate drive heads (seek to track 0)
	for PS/2 35SX, 35LS, 40SX and L40SX, as well as many other systems,
	  both the master drive and the slave drive respond to the Reset
	  function that is issued to either drive
SeeAlso: AH=0Dh,AH=11h,INT 21/AH=0Dh,INT 4D/AH=00h"TI Professional"
SeeAlso: INT 56"Tandy 2000",MEM 0040h:003Eh

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1301 - INT 13 - DISK - GET STATUS OF LAST OPERATION

INT 13 - DISK - GET STATUS OF LAST OPERATION
	AH = 01h
	DL = drive (bit 7 set for hard disk)
Return: CF clear if successful (returned status 00h)
	CF set on error
	AH = status of previous operation (see #00234)
Note:	some BIOSes return the status in AL; the PS/2 Model 30/286 returns the
	  status in both AH and AL
SeeAlso: AH=00h,INT 4D/AH=01h,MEM 0040h:0041h,MEM 0040h:0074h

(Table 00234)
Values for disk operation status:
 00h	successful completion
 01h	invalid function in AH or invalid parameter
 02h	address mark not found
 03h	disk write-protected
 04h	sector not found/read error
 05h	reset failed (hard disk)
 05h	data did not verify correctly (TI Professional PC)
 06h	disk changed (floppy)
 07h	drive parameter activity failed (hard disk)
 08h	DMA overrun
 09h	data boundary error (attempted DMA across 64K boundary or >80h sectors)
 0Ah	bad sector detected (hard disk)
 0Bh	bad track detected (hard disk)
 0Ch	unsupported track or invalid media
 0Dh	invalid number of sectors on format (PS/2 hard disk)
 0Eh	control data address mark detected (hard disk)
 0Fh	DMA arbitration level out of range (hard disk)
 10h	uncorrectable CRC or ECC error on read
 11h	data ECC corrected (hard disk)
 20h	controller failure
 31h	no media in drive (IBM/MS INT 13 extensions)
 32h	incorrect drive type stored in CMOS (Compaq)
 40h	seek failed
 80h	timeout (not ready)
 AAh	drive not ready (hard disk)
 B0h	volume not locked in drive (INT 13 extensions)
 B1h	volume locked in drive (INT 13 extensions)
 B2h	volume not removable (INT 13 extensions)
 B3h	volume in use (INT 13 extensions)
 B4h	lock count exceeded (INT 13 extensions)
 B5h	valid eject request failed (INT 13 extensions)
 B6h	volume present but read protected (INT 13 extensions)
 BBh	undefined error (hard disk)
 CCh	write fault (hard disk)
 E0h	status register error (hard disk)
 FFh	sense operation failed (hard disk)
SeeAlso: #M0022

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1302 - INT 13 - DISK - READ SECTOR(S) INTO MEMORY

INT 13 - DISK - READ SECTOR(S) INTO MEMORY
	AH = 02h
	AL = number of sectors to read (must be nonzero)
	CH = low eight bits of cylinder number
	CL = sector number 1-63 (bits 0-5)
	     high two bits of cylinder (bits 6-7, hard disk only)
	DH = head number
	DL = drive number (bit 7 set for hard disk)
	ES:BX -> data buffer
Return: CF set on error
	    if AH = 11h (corrected ECC error), AL = burst length
	CF clear if successful
	AH = status (see #00234)
	AL = number of sectors transferred (only valid if CF set for some
	      BIOSes)
Notes:	errors on a floppy may be due to the motor failing to spin up quickly
	  enough; the read should be retried at least three times, resetting
	  the disk with AH=00h between attempts
	most BIOSes support "multitrack" reads, where the value in AL
	  exceeds the number of sectors remaining on the track, in which
	  case any additional sectors are read beginning at sector 1 on
	  the following head in the same cylinder; the MSDOS CONFIG.SYS command
	  MULTITRACK (or the Novell DOS DEBLOCK=) can be used to force DOS to
	  split disk accesses which would wrap across a track boundary into two
	  separate calls
	the IBM AT BIOS and many other BIOSes use only the low four bits of
	  DH (head number) since the WD-1003 controller which is the standard
	  AT controller (and the controller that IDE emulates) only supports
	  16 heads
	AWARD AT BIOS and AMI 386sx BIOS have been extended to handle more
	  than 1024 cylinders by placing bits 10 and 11 of the cylinder number
	  into bits 6 and 7 of DH
	under Windows95, a volume must be locked (see INT 21/AX=440Dh/CX=084Bh)
	  in order to perform direct accesses such as INT 13h reads and writes
	all versions of MS-DOS (including MS-DOS 7 [Windows 95]) have a bug
	  which prevents booting on hard disks with 256 heads (FFh), so many
	  modern BIOSes provide mappings with at most 255 (FEh) heads
	some cache drivers flush their buffers when detecting that DOS is
	  bypassed by directly issuing INT 13h from applications.  A dummy
	  read can be used as one of several methods to force cache
	  flushing for unknown caches (e.g. before rebooting).
BUGS:	When reading from floppies, some AMI BIOSes (around 1990-1991) trash
	  the byte following the data buffer, if it is not arranged to an even
	  memory boundary.  A workaround is to either make the buffer word
	  aligned (which may also help to speed up things), or to add a dummy
	  byte after the buffer.
	MS-DOS may leave interrupts disabled on return from this function.
	Apparently some BIOSes or intercepting resident software have bugs
	  that may destroy DX on return or not properly set the Carry flag.
	  At least some Microsoft software frames calls to this function with
	  PUSH DX, STC, INT 13h, STI, POP DX.
	on the original IBM AT BIOS (1984/01/10) this function does not disable
	  interrupts for harddisks (DL >= 80h).	 On these machines the MS-DOS/
	  PC DOS IO.SYS/IBMBIO.COM installs a special filter to bypass the
	  buggy code in the ROM (see CALL F000h:211Eh)
SeeAlso: AH=03h,AH=0Ah,AH=06h"V10DISK.SYS",AH=21h"PS/1",AH=42h"IBM"
SeeAlso: INT 21/AX=440Dh/CX=084Bh,INT 4D/AH=02h

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1303 - INT 13 - DISK - WRITE DISK SECTOR(S)

INT 13 - DISK - WRITE DISK SECTOR(S)
	AH = 03h
	AL = number of sectors to write (must be nonzero)
	CH = low eight bits of cylinder number
	CL = sector number 1-63 (bits 0-5)
	     high two bits of cylinder (bits 6-7, hard disk only)
	DH = head number
	DL = drive number (bit 7 set for hard disk)
	ES:BX -> data buffer
Return: CF set on error
	CF clear if successful
	AH = status (see #00234)
	AL = number of sectors transferred
	      (only valid if CF set for some BIOSes)
Notes:	errors on a floppy may be due to the motor failing to spin up quickly
	  enough; the write should be retried at least three times, resetting
	  the disk with AH=00h between attempts
	most BIOSes support "multitrack" writes, where the value in AL
	  exceeds the number of sectors remaining on the track, in which
	  case any additional sectors are written beginning at sector 1 on
	  the following head in the same cylinder; the CONFIG.SYS command
	  MULTITRACK can be used to force DOS to split disk accesses which
	  would wrap across a track boundary into two separate calls
	the IBM AT BIOS and many other BIOSes use only the low four bits of
	  DH (head number) since the WD-1003 controller which is the standard
	  AT controller (and the controller that IDE emulates) only supports
	  16 heads
	AWARD AT BIOS and AMI 386sx BIOS have been extended to handle more
	  than 1024 cylinders by placing bits 10 and 11 of the cylinder number
	  into bits 6 and 7 of DH
	under Windows95, an application must issue a physical volume lock on
	  the drive via INT 21/AX=440Dh before it can successfully write to
	  the disk with this function
SeeAlso: AH=02h,AH=0Bh,AH=07h"V10DISK.SYS",AH=22h"PS/1",AH=43h"IBM"
SeeAlso: INT 21/AX=440Dh"DOS 3.2+",INT 4D/AH=03h

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1304 - INT 13 - DISK - VERIFY DISK SECTOR(S)

INT 13 - DISK - VERIFY DISK SECTOR(S)
	AH = 04h
	AL = number of sectors to verify (must be nonzero)
	CH = low eight bits of cylinder number
	CL = sector number 1-63 (bits 0-5)
	     high two bits of cylinder (bits 6-7, hard disk only)
	DH = head number
	DL = drive number (bit 7 set for hard disk)
	ES:BX -> data buffer (PC,XT,AT with BIOS prior to 1985/11/15)
Return: CF set on error
	CF clear if successful
	AH = status (see #00234)
	AL = number of sectors verified
Notes:	errors on a floppy may be due to the motor failing to spin up quickly
	  enough (timeout error 80h); the write should be retried at least
	  three times, resetting the disk with AH=00h between attempts
	on floppys, the operation should also be retried on media change
	  (06h) detection.
	this function does not compare the disk with memory, it merely
	  checks whether the sector's stored CRC matches the data's actual CRC
	the IBM AT BIOS and many other BIOSes use only the low four bits of
	  DH (head number) since the WD-1003 controller which is the standard
	  AT controller (and the controller that IDE emulates) only supports
	  16 heads
	AWARD AT BIOS and AMI 386sx BIOS have been extended to handle more
	  than 1024 cylinders by placing bits 10 and 11 of the cylinder number
	  into bits 6 and 7 of DH
BUG:	some Epson ROM BIOSes sometimes have problems properly handling this
	  function. The workaround is to reset the disk (INT 13/AH=00h) before
	  the call.
SeeAlso: AH=02h,AH=44h,INT 4D/AH=04h,INT 4D/AH=06h

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1305 - INT 13 - FLOPPY - FORMAT TRACK

INT 13 - FLOPPY - FORMAT TRACK
	AH = 05h
	AL = number of sectors to format
	CH = track number
	DH = head number
	DL = drive number
	ES:BX -> address field buffer (see #00235)
Return: CF set on error
	CF clear if successful
	AH = status (see #00234)
Notes:	on AT or higher, call AH=17h first
	the number of sectors per track is read from the diskette parameter
	  table pointed at by INT 1E
BUG:	some old Compaq BIOSes have a bug when attempting to call this function
	  from Windows Standard Mode with EMM386 loaded.  A possible workaround
	  is to call this function from Real Mode e.g. through DPMI function
	  "Call Real Mode function with FAR return" (see INT 31/AX=0301h).
SeeAlso: AH=05h"FIXED",AH=17h,AH=18h,INT 1E

Format of floppy format address field buffer entry (one per sector in track):
Offset	Size	Description	(Table 00235)
 00h	BYTE	track number
 01h	BYTE	head number (0-based)
 02h	BYTE	sector number
 03h	BYTE	sector size (00h=128 bytes, 01h=256 bytes, 02h=512, 03h=1024)

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1305 - INT 13 - FIXED DISK - FORMAT TRACK

INT 13 - FIXED DISK - FORMAT TRACK
	AH = 05h
	AL = interleave value (XT-type controllers only)
	ES:BX -> 512-byte format buffer
		the first 2*(sectors/track) bytes contain F,N for each sector
		   F = sector type
			00h for good sector
			20h to unassign from alternate location
			40h to assign to alternate location
			80h for bad sector
		   N = sector number
	CH = cylinder number (bits 8,9 in high bits of CL)
	CL = high bits of cylinder number (bits 7,6)
	DH = head
	DL = drive
Return: CF set on error
	CF clear if successful
	AH = status code (see #00234)
Notes:	AWARD AT BIOS and AMI 386sx BIOS have been extended to handle more
	  than 1024 cylinders by placing bits 10 and 11 of the cylinder number
	  into bits 6 and 7 of DH
	for XT-type controllers on an AT or higher, AH=0Fh should be called
	  first
	the IBM AT BIOS and many other BIOSes use only the low four bits of
	  DH (head number) since the WD-1003 controller which is the standard
	  AT controller (and the controller that IDE emulates) only supports
	  16 heads
	not all controller support sector types 20h and 40h
	under Windows95, an application must issue a physical volume lock on
	  the drive via INT 21/AX=440Dh before it can successfully write to
	  the disk with this function
SeeAlso: AH=05h"FLOPPY",AH=06h"FIXED",AH=07h"FIXED",AH=0Fh,AH=18h,AH=1Ah

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1306 - INT 13 - FIXED DISK - FORMAT TRACK AND SET BAD SECTOR FLAGS (XT,PORT)

INT 13 - FIXED DISK - FORMAT TRACK AND SET BAD SECTOR FLAGS (XT,PORT)
	AH = 06h
	AL = interleave value
	CH = cylinder number (bits 8,9 in high bits of CL)
	CL = sector number
	DH = head
	DL = drive
Return: AH = status code (see #00234)
Note:	AWARD AT BIOS and AMI 386sx BIOS have been extended to handle more
	  than 1024 cylinders by placing bits 10 and 11 of the cylinder number
	  into bits 6 and 7 of DH
SeeAlso: AH=05h"FIXED",AH=07h"FIXED"

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1307 - INT 13 - FIXED DISK - FORMAT DRIVE STARTING AT GIVEN TRACK (XT,PORT)

INT 13 - FIXED DISK - FORMAT DRIVE STARTING AT GIVEN TRACK (XT,PORT)
	AH = 07h
	AL = interleave value (XT only)
	ES:BX = 512-byte format buffer (see AH=05h)
	CH = cylinder number (bits 8,9 in high bits of CL)
	CL = sector number
	DH = head
	DL = drive
Return: AH = status code (see #00234)
Note:	AWARD AT BIOS and AMI 386sx BIOS have been extended to handle more
	  than 1024 cylinders by placing bits 10 and 11 of the cylinder number
	  into bits 6 and 7 of DH
SeeAlso: AH=05h"FIXED",AH=06h"FIXED",AH=1Ah

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1308 - INT 13 - DISK - GET DRIVE PARAMETERS (PC,XT286,CONV,PS,ESDI,SCSI)

INT 13 - DISK - GET DRIVE PARAMETERS (PC,XT286,CONV,PS,ESDI,SCSI)
	AH = 08h
	DL = drive (bit 7 set for hard disk)
	ES:DI = 0000h:0000h to guard against BIOS bugs
Return: CF set on error
	    AH = status (07h) (see #00234)
	CF clear if successful
	    AH = 00h
	    AL = 00h on at least some BIOSes
	    BL = drive type (AT/PS2 floppies only) (see #00242)
	    CH = low eight bits of maximum cylinder number
	    CL = maximum sector number (bits 5-0)
		 high two bits of maximum cylinder number (bits 7-6)
	    DH = maximum head number
	    DL = number of drives
	    ES:DI -> drive parameter table (floppies only)
Notes:	may return successful even though specified drive is greater than the
	  number of attached drives of that type (floppy/hard); check DL to
	  ensure validity
	for systems predating the IBM AT, this call is only valid for hard
	  disks, as it is implemented by the hard disk BIOS rather than the
	  ROM BIOS
	the IBM ROM-BIOS returns the total number of hard disks attached
	  to the system regardless of whether DL >= 80h on entry.
	Toshiba laptops with HardRAM return DL=02h when called with DL=80h,
	  but fail on DL=81h.  The BIOS data at 40h:75h correctly reports 01h.
	may indicate only two drives present even if more are attached; to
	  ensure a correct count, one can use AH=15h to scan through possible
	  drives
	Reportedly some Compaq BIOSes with more than one hard disk controller
	  return only the number of drives DL attached to the corresponding
	  controller as specified by the DL value on entry.  However, on
	  Compaq machines with "COMPAQ" signature at F000h:FFEAh,
	  MS-DOS/PC DOS IO.SYS/IBMBIO.COM call INT 15/AX=E400h and 
	  INT 15/AX=E480h to enable Compaq "mode 2" before retrieving the count
	  of hard disks installed in the system (DL) from this function.
	the maximum cylinder number reported in CX is usually two less than
	  the total cylinder count reported in the fixed disk parameter table
	  (see INT 41h,INT 46h) because early hard disks used the last cylinder
	  for testing purposes; however, on some Zenith machines, the maximum
	  cylinder number reportedly is three less than the count in the fixed
	  disk parameter table.
	for BIOSes which reserve the last cylinder for testing purposes, the
	  cylinder count is automatically decremented
	on PS/1s with IBM ROM DOS 4, nonexistent drives return CF clear,
	  BX=CX=0000h, and ES:DI = 0000h:0000h
	machines with lost CMOS memory may return invalid data for floppy
	  drives. In this situation CF is cleared, but AX,BX,CX,DX,DH,DI,
	  and ES contain only 0.  At least under some circumstances, MS-DOS/
	  PC DOS IO.SYS/IBMBIO.COM just assumes a 360 KB floppy if it sees
	  CH to be zero for a floppy.
	the PC-Tools PCFORMAT program requires that AL=00h before it will
	  proceed with the formatting
	if this function fails, an alternative way to retrieve the number
	  of floppy drives installed in the system is to call INT 11h.
	In fact, the MS-DOS/PC-DOS IO.SYS/IBMBIO.COM attempts to get the
	  number of floppy drives installed from INT 13/AH=08h, when INT 11h
	  AX bit 0 indicates there are no floppy drives installed. In addition
	  to testing the CF flag, it only trusts the result when the number of
	  sectors (CL preset to zero) is non-zero after the call.
BUGS:	several different Compaq BIOSes incorrectly report high-numbered
	  drives (such as 90h, B0h, D0h, and F0h) as present, giving them the
	  same geometry as drive 80h; as a workaround, scan through disk
	  numbers, stopping as soon as the number of valid drives encountered
	  equals the value in 0040h:0075h
	a bug in Leading Edge 8088 BIOS 3.10 causes the DI,SI,BP,DS, and ES
	  registers to be destroyed
	some Toshiba BIOSes (at least before 1995, maybe some laptops???
	  with 1.44 MB floppies) have a bug where they do not set the ES:DI
	  vector even for floppy drives. Hence these registers should be
	  preset with zero before the call and checked to be non-zero on
	  return before using them.  Also it seems these BIOSes can return
	  wrong info in BL and CX, as S/DOS 1.0 can be configured to preset
	  these registers as for an 1.44 MB floppy.
	the PS/2 Model 30 fails to reset the bus after INT 13/AH=08h and
	  INT 13/AH=15h. A workaround is to monitor for these functions
	  and perform a transparent INT 13/AH=01h status read afterwards.
	  This will reset the bus. The MS-DOS 6.0 IO.SYS takes care of
	  this by installing a special INT 13h interceptor for this purpose.
	AD-DOS may leave interrupts disabled on return from this function.
	Some Microsoft software explicitly sets STI after return.
SeeAlso: AH=06h"Adaptec",AH=13h"SyQuest",AH=48h,AH=15h,INT 1E
SeeAlso: INT 41"HARD DISK 0"

(Table 00242)
Values for diskette drive type:
 01h	360K
 02h	1.2M
 03h	720K
 04h	1.44M
 05h	??? (reportedly an obscure drive type shipped on some IBM machines)
	2.88M on some machines (at least AMI 486 BIOS)
 06h	2.88M
 10h	ATAPI Removable Media Device

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1309 - INT 13 - HARD DISK - INITIALIZE CONTROLLER WITH DRIVE PARAMETERS (AT,PS)

INT 13 - HARD DISK - INITIALIZE CONTROLLER WITH DRIVE PARAMETERS (AT,PS)
	AH = 09h
	DL = drive (80h for first, 81h for second)
Return: CF clear if successful
	CF set on error
	AH = status (see #00234)
Notes:	on the PC and XT, this function uses the parameter table pointed at by
	  INT 41
	on the AT and later, this function uses the parameter table pointed at
	  by INT 41 if DL=80h, and the parameter table pointed at by INT 46 if
	  DL=81h
SeeAlso: INT 41"HARD DISK 0",INT 46"HARD DISK 1"

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130A - INT 13 - HARD DISK - READ LONG SECTOR(S) (AT and later)

INT 13 - HARD DISK - READ LONG SECTOR(S) (AT and later)
	AH = 0Ah
	AL = number of sectors (01h may be only value supported)
	CH = low eight bits of cylinder number
	CL = sector number (bits 5-0)
	     high two bits of cylinder number (bits 7-6)
	DH = head number
	DL = drive number (80h = first, 81h = second)
	ES:BX -> data buffer
Return: CF clear if successful
	CF set on error
	AH = status (see #00234)
	AL = number of sectors transferred
Notes:	this function reads in four to seven bytes of error-correcting code
	  along with each sector's worth of information
	data errors are not automatically corrected, and the read is aborted
	  after the first sector with an ECC error
	used for diagnostics only on PS/2 systems; IBM officially classifies
	  this function as optional
BUG:	on the original IBM AT BIOS (1984/01/10) this function does not disable
	  interrupts for harddisks (DL >= 80h). On these machines the MS-DOS/
	  PC DOS IO.SYS/IBMBIO.COM installs a special filter to bypass the
	  buggy code in the ROM (see CALL F000h:211Eh)
SeeAlso: AH=02h,AH=0Bh,MEM 0040h:0074h

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130B - INT 13 - HARD DISK - WRITE LONG SECTOR(S) (AT and later)

INT 13 - HARD DISK - WRITE LONG SECTOR(S) (AT and later)
	AH = 0Bh
	AL = number of sectors (01h may be only value supported)
	CH = low eight bits of cylinder number
	CL = sector number (bits 5-0)
	     high two bits of cylinder number (bits 7-6)
	DH = head number
	DL = drive number (80h = first, 81h = second)
	ES:BX -> data buffer
Return: CF clear if successful
	CF set on error
	AH = status (see #00234)
	AL = number of sectors transferred
Notes:	each sector's worth of data must be followed by four to seven bytes of
	  error-correction information
	used for diagnostics only on PS/2 systems; IBM officially classifies
	  this function as optional
SeeAlso: AH=03h,AH=0Ah,MEM 0040h:0074h

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130C - INT 13 - HARD DISK - SEEK TO CYLINDER

INT 13 - HARD DISK - SEEK TO CYLINDER
	AH = 0Ch
	CH = low eight bits of cylinder number
	CL = sector number (bits 5-0)
	    high two bits of cylinder number (bits 7-6)
	DH = head number
	DL = drive number (80h = first, 81h = second hard disk)
Return: CF set on error
	CF clear if successful
	AH = status (see #00234)
SeeAlso: AH=00h,AH=02h,AH=0Ah,AH=47h

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130D - INT 13 - HARD DISK - RESET HARD DISKS

INT 13 - HARD DISK - RESET HARD DISKS
	AH = 0Dh
	DL = drive number (80h = first, 81h = second hard disk)
Return: CF set on error
	CF clear if successful
	AH = status (see #00234)
Notes:	reinitializes the hard disk controller, resets the specified drive's
	  parameters, and recalibrates the drive's heads (seek to track 0)
	for PS/2 35SX, 35LS, 40SX and L40SX, as well as many other systems,
	  both the master drive and the slave drive respond to the Reset
	  function that is issued to either drive
	not for PS/2 ESDI drives
SeeAlso: AH=00h,INT 21/AH=0Dh

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130E - INT 13 - HARD DISK - READ SECTOR BUFFER (XT only)

INT 13 - HARD DISK - READ SECTOR BUFFER (XT only)
	AH = 0Eh
	DL = drive number (80h = first, 81h = second hard disk)
	ES:BX -> buffer
Return: CF set on error
	CF clear if successful
	AH = status code (see #00234)
Notes:	transfers controller's sector buffer.  No data is read from the drive
	used for diagnostics only on PS/2 systems
SeeAlso: AH=0Ah

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130F - INT 13 - HARD DISK - WRITE SECTOR BUFFER (XT only)

INT 13 - HARD DISK - WRITE SECTOR BUFFER (XT only)
	AH = 0Fh
	DL = drive number (80h = first, 81h = second hard disk)
	ES:BX -> buffer
Return: CF set on error
	CF clear if successful
	AH = status code (see #00234)
Notes:	does not write data to the drive
	should be called before formatting to initialize an XT-type
	  controller's sector buffer
	used for diagnostics only on PS/2 systems
SeeAlso: AH=0Bh

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1310 - INT 13 - HARD DISK - CHECK IF DRIVE READY

INT 13 - HARD DISK - CHECK IF DRIVE READY
	AH = 10h
	DL = drive number (80h = first, 81h = second hard disk)
Return: CF set on error
	CF clear if successful
	AH = status (see #00234 at AH=01h)
SeeAlso: AH=11h

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1311 - INT 13 - HARD DISK - RECALIBRATE DRIVE

INT 13 - HARD DISK - RECALIBRATE DRIVE
	AH = 11h
	DL = drive number (80h = first, 81h = second hard disk)
Return: CF set on error
	CF clear if successful
	AH = status (see #00234 at AH=01h)
Note:	causes hard disk controller to seek the specified drive to cylinder 0
SeeAlso: AH=00h,AH=0Ch,AH=10h,AH=19h"FIXED DISK",MEM 0040h:003Eh

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1312 - INT 13 - HARD DISK - CONTROLLER RAM DIAGNOSTIC (XT,PS)

INT 13 - HARD DISK - CONTROLLER RAM DIAGNOSTIC (XT,PS)
	AH = 12h
	DL = drive number (80h = first, 81h = second hard disk)
Return: CF set on error
	CF clear if successful
	AH = status code (see #00234 at AH=01h)
	AL = 00h
SeeAlso: AH=13h,AH=14h

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1313 - INT 13 - HARD DISK - DRIVE DIAGNOSTIC (XT,PS)

INT 13 - HARD DISK - DRIVE DIAGNOSTIC (XT,PS)
	AH = 13h
	DL = drive number (80h = first, 81h = second hard disk)
Return: CF set on error
	CF clear if successful
	AH = status code (see #00234 at AH=01h)
	AL = 00h
SeeAlso: AH=12h"HARD DISK",AH=14h"HARD DISK"

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1314 - INT 13 - HARD DISK - CONTROLLER INTERNAL DIAGNOSTIC

INT 13 - HARD DISK - CONTROLLER INTERNAL DIAGNOSTIC
	AH = 14h
Return: CF set on error
	CF clear if successful
	AH = status code (see #00234 at AH=01h)
	AL = 00h
SeeAlso: AH=12h,AH=13h

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1315 - INT 13 - DISK - GET DISK TYPE (XT 1986/1/10 or later,XT286,AT,PS)

INT 13 - DISK - GET DISK TYPE (XT 1986/1/10 or later,XT286,AT,PS)
	AH = 15h
	DL = drive number (bit 7 set for hard disk)
	(AL = FFh, CX = FFFFh, see Note)
Return: CF clear if successful
	    AH = type code
		00h no such drive
		    (SpeedStor) AL = 03h hard disk
				    CX:DX = number of 512-byte sectors
		01h floppy without change-line support
		02h floppy (or other removable drive) with change-line support
		03h hard disk
		    CX:DX = number of 512-byte sectors
	CF set on error
	    AH = status (see #00234 at AH=01h)
Note:	SyQuest can report type 01h or 02h for 'hard disks', since its media
	  is removable
BUGS:	many versions of the Award 486 BIOS do not return the sector count
	  because the BIOS exit code restores CX and DX to their original
	  values after the function had already set them to correct values
	Some releases of PC Tools REBUILD preset CX=FFFFh and only trust the
	  results if CH <= 2 on return (which would cut off drives > 16 Gb).
	several different Compaq BIOSes incorrectly report high-numbered
	  drives (such as 90h, B0h, D0h, and F0h) as present, giving them the
	  same geometry as drive 80h; as a workaround, scan through disk
	  numbers, stopping as soon as the number of valid drives encountered
	  equals the value in 0040h:0075h
	the PS/2 Model 30 fails to reset the bus after INT 13/AH=08h and
	  INT 13/AH=15h.  A workaround is to monitor for these functions
	  and perform a transparent INT 13/AH=01h status read afterwards.
	  This will reset the bus. The MS-DOS 6.0 IO.SYS takes care of
	  this by installing a special INT 13h interceptor for this purpose.
	Some releases of SpeedStor have a bug where it reports AX=0003h instead
	  of correctly reporting AH=03h for hard disks. A possible workaround
	  when testing for hard disks is to check for AH=03h and AX=0003h.
	  In this case this function should be invoked with a bogus fixed
	  value in AL, e.g. AL=FFh.
SeeAlso: AH=08h,AH=16h,AH=17h,AH=19h"SCSI",MEM 0040h:0075h

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1316 - INT 13 - FLOPPY DISK - DETECT DISK CHANGE (XT 1986/1/10 or later,XT286,AT,PS)

INT 13 - FLOPPY DISK - DETECT DISK CHANGE (XT 1986/1/10 or later,XT286,AT,PS)
	AH = 16h
	DL = drive number (00h-7Fh)
	SI = 0000h (to avoid crash on AT&T 6300)
Return: CF clear if change line inactive
	    AH = 00h (disk not changed)
	CF set if change line active
	    AH = status
		01h invalid command (SyQuest)
		06h change line active or not supported
		80h drive not ready or not present
Notes:	call AH=15h first to determine whether the drive supports a change
	  line
	this call also clears the media-change status, so that a disk change
	  is only reported once
BUGS:	some versions of Award 386 Modular BIOS and AMI BIOS fail to clear
	  the media-change status
	AT&T 6300 WGS systems crash if SI <> 0 on entry.
	some pre 1986/08/04 Compaq ROM BIOS have a serious bug where this
	  function may re-configure a hard disk depending on what is located
	  at ES:[BX] and data indexed to by it. MS-DOS/PC DOS IO.SYS/IBMBIO.COM
	  install a special filter when they detect Compaq ROM BIOSes with
	  earlier dates.
	some Compaq 286 systems have a bug in all INT 13h functions >= 16h,
	  which causes the byte at DS:0074h to be destroyed when called for
	  hard disks (DL >= 80h). MS-DOS/PC DOS IO.SYS/IBMBIO.COM performs a
	  test on this bug using this sub-function, and if found installs a
	  special filter which points DS into ROM, so that it cannot cause
	  any harm.
	some drives (or controllers???) forget the change line status
	  if another drive is accessed afterwards. The DOS BIOS takes care
	  of this by not relying on the reported change line status when
	  the change line is not active and a different drive is accessed,
	  instead it reports "don't know" to the DOS kernel.
SeeAlso: AH=15h,AH=49h

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1317 - INT 13 - FLOPPY DISK - SET DISK TYPE FOR FORMAT (AT,PS)

INT 13 - FLOPPY DISK - SET DISK TYPE FOR FORMAT (AT,PS)
	AH = 17h
	AL = format type
	    01h = 320/360K disk in 360K drive
	    02h = 320/360K disk in 1.2M drive
	    03h = 1.2M disk in 1.2M drive
	    04h = 720K disk in 720K or 1.44M drive
	DL = drive number
Return: CF set on error
	CF clear if successful
	AH = status (see #00234 at AH=01h)
Note:	this function does not handle 1.44M drives; use AH=18h instead
SeeAlso: AH=15h,AH=18h

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1318 - INT 13 - DISK - SET MEDIA TYPE FOR FORMAT (AT model 3x9,XT2,XT286,PS)

INT 13 - DISK - SET MEDIA TYPE FOR FORMAT (AT model 3x9,XT2,XT286,PS)
	AH = 18h
	DL = drive number
	CH = lower 8 bits of highest cylinder number (number of cylinders - 1)
	CL = sectors per track (bits 0-5)
	     top 2 bits of highest cylinder number (bits 6,7)
Return: AH = status
	    00h requested combination supported
	    01h function not available
	    0Ch not supported or drive type unknown
	    80h there is no disk in the drive
	ES:DI -> 11-byte parameter table (see #01264 at INT 1E)
Note:	this function does not set the INT 1E vector to point at the returned
	  parameter table; it is the caller's responsibility to do so
SeeAlso: AH=05h,AH=07h,AH=17h,INT 1E

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1319 - INT 13 - FIXED DISK - PARK HEADS ON ESDI DRIVE (XT286,PS)

INT 13 - FIXED DISK - PARK HEADS ON ESDI DRIVE (XT286,PS)
	AH = 19h
	DL = drive
Return: CF set on error
	CF clear if successful
	AH = status (see #00234 at AH=01h)
SeeAlso: AH=11h

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13FF - INT 13 - IBM SurePath BIOS - Officially "Private" Function

INT 13 - IBM SurePath BIOS - Officially "Private" Function
	AH = FFh

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1500 - INT 15 - CASSETTE - TURN ON TAPE DRIVE'S MOTOR (PC and PCjr only)

INT 15 - CASSETTE - TURN ON TAPE DRIVE'S MOTOR (PC and PCjr only)
	AH = 00h
Return: CF set on error
	    AH = 86h no cassette present
	CF clear if successful
SeeAlso: AH=01h"CASSETTE",MEM 0040h:0067h"PC"

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1501 - INT 15 - CASSETTE - TURN OFF TAPE DRIVE'S MOTOR (PC and PCjr only)

INT 15 - CASSETTE - TURN OFF TAPE DRIVE'S MOTOR (PC and PCjr only)
	AH = 01h
Return: CF set on error
	    AH = 86h no cassette present
	CF clear if successful
SeeAlso: AH=00h"CASSETTE"

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1502 - INT 15 - CASSETTE - READ DATA (PC and PCjr only)

INT 15 - CASSETTE - READ DATA (PC and PCjr only)
	AH = 02h
	CX = number of bytes to read
	ES:BX -> buffer
Return: CF clear if successful
	    DX = number of bytes read
	    ES:BX -> byte following last byte read
	CF set on error
	AH = status (see #00409)
SeeAlso: AH=00h"CASSETTE",AH=03h"CASSETTE",MEM 0040h:0069h,MEM 0040h:006Bh"PC"

(Table 00409)
Values for Cassette status:
 00h	successful
 01h	CRC error
 02h	bad tape signals
 04h	no data
 80h	invalid command
 86h	no cassette present

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1503 - INT 15 - CASSETTE - WRITE DATA (PC and PCjr only)

INT 15 - CASSETTE - WRITE DATA (PC and PCjr only)
	AH = 03h
	CX = number of bytes to write
	ES:BX -> data buffer
Return: CF clear if successful
	    ES:BX -> byte following last byte written
	CF set on error
	AH = status (see #00409)
	CX = 0000h
SeeAlso: AH=00h"CASSETTE",AH=02h"CASSETTE"

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1504 - INT 15 - SYSTEM - BUILD ABIOS SYSTEM PARAMETER TABLE (PS)

INT 15 - SYSTEM - BUILD ABIOS SYSTEM PARAMETER TABLE (PS)
	AH = 04h
	ES:DI -> 32-byte results buffer for System Parameter Table (see #00410)
	DS = segment containing ABIOS RAM extensions (zero if none)
Return: CF clear if successful
	    AH = 00h success
	    ES:DI buffer filled
	    AL destroyed
	CF set on failure
	    AX destroyed
	    AH = 80h/86h if not supported
SeeAlso: AH=05h"ABIOS",AH=C1h

Format of ABIOS System Parameter Table:
Offset	Size	Description	(Table 00410)
 00h	DWORD	FAR address of ABIOS Common Start Routine
 04h	DWORD	FAR address of ABIOS Interrupt Routine
 08h	DWORD	FAR address of ABIOS Time-out Routine
 0Ch	WORD	number of bytes of stack required by this ABIOS implementation
 0Eh 16 BYTEs	reserved
 1Eh	WORD	number of entries in initialization table

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1505 - INT 15 - SYSTEM - BUILD ABIOS INITIALIZATION TABLE (PS)

INT 15 - SYSTEM - BUILD ABIOS INITIALIZATION TABLE (PS)
	AH = 05h
	ES:DI -> results buffer of length 18h * Number_of_Entries (see #00411)
	DS = segment containing ABIOS RAM extensions (zero if none)
Return: CF clear if successful
	    AH = 00h success
	    ES:DI buffer filled
	    AL destroyed
	CF set on failure
	    AX destroyed
	    AH = 80h/86h if not supported
SeeAlso: AH=04h"ABIOS",AH=C1h

Format of one entry of ABIOS Initialization Table:
Offset	Size	Description	(Table 00411)
 00h	WORD	device ID (see #00412)
 02h	WORD	number of Logical IDs
 04h	WORD	Device Block length (zero for ABIOS patch or extension)
 06h	DWORD	-> init routine for Device Block and Function Transfer Table
 0Ah	WORD	request block length
 0Ch	WORD	Function Transfer Table length (zero for a patch)
 0Eh	WORD	Data Pointers length (in Common Data Area)
 10h	BYTE	secondary device ID (hardware level this ABIOS ver supports)
 11h	BYTE	revision (device driver revision level this ABIOS supports)
 12h  6 BYTEs	reserved

(Table 00412)
Values for ABIOS device ID:
 00h	ABIOS internal calls
 01h	floppy disk
 02h	hard disk
 03h	video
 04h	keyboard
 05h	parallel port
 06h	serial port
 07h	system timer
 08h	real-time clock
 09h	system services
 0Ah	NMI
 0Bh	mouse
 0Eh	CMOS RAM
 0Fh	DMA
 10h	Programmable Option Select (POS)
 16h	keyboard password

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1508 - INT 15 - IBM SurePath BIOS - WAIT REQUESTED TIME PERIOD

INT 15 - IBM SurePath BIOS - WAIT REQUESTED TIME PERIOD
	AH = 08h
	AL = function
	    00h wait in increments of 15.025 microseconds
		CX = number of time increments to wait (0000h = maximum)
	    80h wait in increments of 840 ns
		ECX = number of time increments to wait
	    81h I/O event wait
		BH = bitmask of bits to check
		BL = expected pattern
		DX = I/O port address
		ECX = number of 840 ns microticks to wait
		Return: ECX = 00000000h if expected pattern did not occur
	    82h memory event wait
		BH = bitmask of bits to check
		BL = expected pattern
		ES:SI -> BYTE to check
		ECX = number of 840 ns microticks to wait
		Return: ECX = 00000000h if expected pattern did not occur
	    other reserved
Return: CF clear if successful
	CF set on error
	AH = status
	    00h successful
	    01h used 15.025 microsecond interval, time rounded up
	    08h reserved subfunction
	    86h function not supported
Notes:	IBM classifies this function as optional
	if the POST determines that the timer is nonfunctional, this function
	  uses the 15.025 microsecond refresh timer instead of the
	  full-resolution timer
SeeAlso: AH=07h"IBM",AH=09h"IBM",AH=86h

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1521 - INT 15 - SYSTEM - POWER-ON SELF-TEST ERROR LOG (PS50+)

INT 15 - SYSTEM - POWER-ON SELF-TEST ERROR LOG (PS50+)
	AH = 21h
	AL = subfunction
	    00h read POST log
	    01h write POST log
		BH = device ID
		BL = error code
Return: CF clear if successful
	CF set on error
	AH = status
	    00h OK
	    01h list full
	    02h unsupported subfunction
	    80h invalid command
	    86h unsupported function
	if function 00h:
	   BX = number of error codes stored
	   ES:DI -> error log
Notes:	the log is a series of words, the first byte of which identifies the
	  error code and the second the device.
	supported by AMI PCI BIOS
	IBM considers this a required BIOS function
	if the device ID is FFh, the "error code" is the actual device number
	  minus 255 (thus these devices have no specific error codes)
SeeAlso: AH=23h"SYSTEM",AH=24h"SYSTEM"

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1522 - INT 15 - SYSTEM - later PS/2s - LOCATE ROM BASIC

INT 15 - SYSTEM - later PS/2s - LOCATE ROM BASIC
	AH = 22h
Return: CF set on error
	    AH = status (86h if function not supported)
	CF clear on success
	    AH = 00h
	    ES:BX -> ROM BASIC
Notes:	if this function is not supported, ROM BASIC is at F600h:0000h
	IBM classifies this function as optional
SeeAlso: INT 86"BASIC",INT F0"BASIC"

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152300 - INT 15 u - IBM BIOS - SMART ENERGY SYSTEM - GET ??? CMOS DATA

INT 15 u - IBM BIOS - SMART ENERGY SYSTEM - GET ??? CMOS DATA
	AX = 2300h
Return: CF clear if successful
	    CL = value of CMOS location 2Dh
	    CH = value of CMOS location 2Eh
	CF set on error
	    AH = error code (80h,86h)
Note:	IBM classifies this function as optional
SeeAlso: AX=2301h,AX=2304h,AX=2305h

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152301 - INT 15 u - IBM BIOS - SMART ENERGY SYSTEM - SET ??? CMOS DATA

INT 15 u - IBM BIOS - SMART ENERGY SYSTEM - SET ??? CMOS DATA
	AX = 2301h
	CL = new value for CMOS location 2Dh
	CH = new value for CMOS location 2Eh
Return: CF clear if successful
	CF set on error
	    AH = error code (80h,86h)
Notes:	sets the contents of CMOS locations 2Dh and 2Eh
	IBM classifies this function as optional
SeeAlso: AX=2300h,AX=2304h,AX=2305h

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152302 - INT 15 u - IBM BIOS - SMART ENERGY SYSTEM - GET ROM STARTUP VIDEO REG TABLES

INT 15 u - IBM BIOS - SMART ENERGY SYSTEM - GET ROM STARTUP VIDEO REG TABLES
	AX = 2302h
	BL = data index (00h-0Dh) (see #00459)
Return: ES:BX -> table for register (see #00460,#00461)
	CX = size of table in bytes (may be 0000h)
Note:	IBM classifies this function as optional
SeeAlso: AX=2300h,AX=2301h,AX=2303h

(Table 00459)
Values for PS/1 ROM startup video register tables:
 00h	DAC registers
 01h	???
 02h	Palette registers
 03h-0Dh ???

Format of PS/1 ROM startup DAC register table:
Offset	Size	Description	(Table 00460)
 00h	WORD	number of DAC registers in table
 02h	var	array of 3-byte DAC register values, starting at register 00h
SeeAlso: #00459

Format of PS/1 ROM startup Palette register table:
Offset	Size	Description	(Table 00461)
 00h 16 BYTEs	colors for palette registers 00h through 0Fh
 10h	BYTE	border color
SeeAlso: #00459,#00018

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152303 - INT 15 U - IBM BIOS - SMART ENERGY SYSTEM - ???

INT 15 U - IBM BIOS - SMART ENERGY SYSTEM - ???
	AX = 2303h
	BX = ??? ('x')
	DX = 'y' and 'z'
		bits 15-7 = 'y'
		bits 6-3 unused
		bits 2-0 = 'z'
	DI = ??? (0352h)
Return: ???
Notes:	performs graphics functions, writes to segment A000h and VGA I/O ports
	IBM classifies this function as optional

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152304 - INT 15 u - IBM BIOS - SMART ENERGY SYSTEM - SYSTEM SETUP

INT 15 u - IBM BIOS - SMART ENERGY SYSTEM - SYSTEM SETUP
	AX = 2304h
	DX = segment of 32K buffer
Return: CF clear if successful
	    AX = 0003h (left over from setting video mode 3)
	    BX,CX,DX,BP,DS,ES destroyed
	CF set on error
	    AH = error code (80h,86h)
Desc:	run system setup utility, and optionally save any changed settings to
	  CMOS RAM
Note:	IBM classifies this function as optional
SeeAlso: AX=2301h,AX=2305h

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152305 - INT 15 u - IBM BIOS - SMART ENERGY SYSTEM - GET PROCESSOR SPEED

INT 15 u - IBM BIOS - SMART ENERGY SYSTEM - GET PROCESSOR SPEED
	AX = 2305h
Return: CF clear if successful
	    AL = processor speed in MHz
	CF set on error
	    AL = FFh (speed unknown or >80 MHz)
	    AL = error code (80h,86h = unsupported function)
Note:	IBM classifies this function as optional
SeeAlso: AX=2301h,AX=2304h,AH=BCh

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1540 - INT 15 - SYSTEM - READ/MODIFY PROFILES (CONVERTIBLE)

INT 15 - SYSTEM - READ/MODIFY PROFILES (CONVERTIBLE)
	AH = 40h
	AL = subfunction
	    00h get system profile in CX and BX
	    01h set system profile from CX and BX
	    02h get internal modem profile in BX
	    03h set internal modem profile from BX
Return: CF clear if successful
	    AH = 00h
	CF set on error
	    AH = status (80h = profile execution failed)

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1541 - INT 15 - SYSTEM - WAIT ON EXTERNAL EVENT (CONVERTIBLE and some others)

INT 15 - SYSTEM - WAIT ON EXTERNAL EVENT (CONVERTIBLE and some others)
	AH = 41h
	AL = condition type (see #00463)
	BH = condition compare or mask value
	BL = timeout value times 55 milliseconds
	    00h means no timeout
	DX = I/O port address if AL bit 4 set
	ES:DI -> user byte if AL bit 4 clear
Return: after event or timeout occurs
Note:	call AH=C0h and examine bit 3 of feature byte 1 to determine whether
	  this function is supported
SeeAlso: AH=83h,AH=86h,AH=C0h

Bitfields for external event wait condition type:
Bit(s)	Description	(Table 00463)
 0-2	condition to wait for
	0 any external event
	1 compare and return if equal
	2 compare and return if not equal
	3 test and return if not zero
	4 test and return if zero
 3	reserved
 4	1=port address, 0=user byte
 5-7	reserved

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1542 - INT 15 - SYSTEM - REQUEST POWER OFF (CONVERTIBLE,HP 95LX)

INT 15 - SYSTEM - REQUEST POWER OFF (CONVERTIBLE,HP 95LX)
	AH = 42h
	AL = suspend type
	    00h to use system profile
	    01h to force suspend regardless of system profile
Return: nothing
Note:	the HP 95LX apparently suspends regardless of the value in AL; on
	  power-up, execution will resume following the instruction calling
	  this function
SeeAlso: AH=44h

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1543 - INT 15 - SYSTEM - READ SYSTEM STATUS (CONVERTIBLE)

INT 15 - SYSTEM - READ SYSTEM STATUS (CONVERTIBLE)
	AH = 43h
Return: AL = status bits (see #00464)

Bitfields for Convertible system status:
Bit(s)	Description	(Table 00464)
 7	power low
 6	external power in use
 5	standby power lost
 4	power activated by alarm
 3	internal modem powered on
 2	RS232/parallel adapter powered on
 1	reserved
 0	LCD detached

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1544 - INT 15 - SYSTEM - (DE)ACTIVATE INTERNAL MODEM POWER (CONVERTIBLE)

INT 15 - SYSTEM - (DE)ACTIVATE INTERNAL MODEM POWER (CONVERTIBLE)
	AH = 44h
	AL = new modem power state (00h power off, 01h power on)
Return: nothing
SeeAlso: AH=42h

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1544F1 - INT 15 U - Toshiba laptops - SECURITY LEVEL CHECK

INT 15 U - Toshiba laptops - SECURITY LEVEL CHECK
	AX = 44F1h
	DS:DX -> byte with 00h ???
Return: ???
Note:	used by Toshiba BIOS setup utility TSETUP.EXE to distinguish
	  between USER and SUPERVISOR security level
SeeAlso: AX=44F2h,AX=44F3h

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1544F2BX0604 - INT 15 U - Toshiba laptops - SECURITY LEVEL CHECK

INT 15 U - Toshiba laptops - SECURITY LEVEL CHECK
	AX = 44F2h
	BX = 0604h ???
Return: CF = ???
	AH = ???
	DX = ???
Note:	used by Toshiba BIOS setup utility TSETUP.EXE to distinguish
	  between USER and SUPERVISOR security level
SeeAlso: AX=44F1h,AX=44F3h

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1544F3 - INT 15 U - Toshiba laptops - SECURITY LEVEL CHECK

INT 15 U - Toshiba laptops - SECURITY LEVEL CHECK
	AX = 44F3h
	DS:DX -> byte with 00h or 01h ???
Return: DS:DX -> changed ???
Note:	used by Toshiba BIOS setup utility TSETUP.EXE to distinguish
	  between USER and SUPERVISOR security level
SeeAlso: AX=44F1h,AX=44F2h

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154F - INT 15 C - KEYBOARD - KEYBOARD INTERCEPT (AT model 3x9,XT2,XT286,CONV,PS)

INT 15 C - KEYBOARD - KEYBOARD INTERCEPT (AT model 3x9,XT2,XT286,CONV,PS)
	AH = 4Fh
	AL = hardware scan code (see #00006)
	CF set
Return: CF set to continue processing scan code
	   AL = possibly-altered hardware scan code (see #00006)
	CF clear
	   scan code should be ignored
Notes:	called by INT 09 handler to translate scan codes; the INT 09 code does
	  not examine the scan code it reads from the keyboard until after
	  this function returns.  This permits software to rearrange the
	  keyboard; for example, swapping the CapsLock and Control keys, or
	  turning the right Shift key into Enter.
	DOS 6 KEYB.COM will not pass through this function if Ctrl-Alt-Del is
	  pressed and a SmartDrive v4-compatible cache is installed which has
	  dirty cache buffers; some other disk caches such as HyperDisk
	  operate similarly in order to prevent loss of cached data which has
	  not yet been written to disk
	IBM classifies this function as required
SeeAlso: INT 09,INT 15/AH=C0h

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155101 - INT 15 - SYSTEM - later PS/2s - EXPANSION UNIT, RETURN CONFIGURATION NUMBER

INT 15 - SYSTEM - later PS/2s - EXPANSION UNIT, RETURN CONFIGURATION NUMBER
	AX = 5101h
Return: CF set if successful
	    AH = 00h
	    AL = current configuration number
		00h system unit only
		FFh configuration not recognized
	    BX = status flag
		bits 0-14: reserved
		bit 15: additional data is available (location TBD)
	CF clear on error
	    AH = status
		01h expansion unit is not present
		86h function not supported
Note:	CF convention is the reverse of the standard convention for this
	  interrupt.  (Perhaps a typo in the IBM BIOS Tech Ref?)

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1580 - INT 15 C - OS HOOK - DEVICE OPEN (AT,XT286,PS)

INT 15 C - OS HOOK - DEVICE OPEN (AT,XT286,PS)
	AH = 80h
	BX = device ID
	CX = process ID
	CF clear
Return: CF clear if successful
	    AH = 00h
	CF set on error
	    AH = status (see #00496)
Note:	this function should be hooked by a multitasker which wishes to keep
	  track of device ownership; the default BIOS handler merely returns
	  successfully
SeeAlso: AH=81h,AH=82h

(Table 00496)
Values for status:
 80h	invalid command (PC,PCjr)
 86h	function not supported (XT)

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1581 - INT 15 C - OS HOOK - DEVICE CLOSE

INT 15 C - OS HOOK - DEVICE CLOSE
	AH = 81h
	BX = device ID
	CX = process ID
	CF clear
Return: CF clear if successful
	    AH = 00h
	CF set on error
	    AH = status (see #00496)
Note:	this function should be hooked by a multitasker which wishes to keep
	  track of device ownership; the default BIOS handler merely returns
	  successfully
SeeAlso: AH=80h,AH=82h

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1582 - INT 15 C - OS HOOK - PROGRAM TERMINATION

INT 15 C - OS HOOK - PROGRAM TERMINATION
	AH = 82h
	BX = process ID
	CF clear
Return: CF clear if successful
	    AH = 00h
	CF set on error
	    AH = status (see #00496)
Notes:	closes all devices opened by the given process ID with function 80h
	this function should be hooked by a multitasker which wishes to keep
	  track of device ownership; the default BIOS handler merely returns
	  successfully
SeeAlso: AH=80h,AH=81h

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1583 - INT 15 - BIOS - SET EVENT WAIT INTERVAL (AT,PS50+)

INT 15 - BIOS - SET EVENT WAIT INTERVAL (AT,PS50+)
	AH = 83h
	AL = subfunction
	    00h set interval
		CX:DX = microseconds to delay
		ES:BX -> byte whose high bit is to be set at end of interval
	    01h cancel wait interval
Return: CF set on error or function already busy
	    AH = status
		80h invalid command (PC,PCjr)
		86h function not supported (XT and later)
	CF clear if successful
Notes:	the resolution of the wait period is 977 microseconds on many systems
	  because many BIOSes use the 1/1024 second fast interrupt from the AT
	  real-time clock chip which is available on INT 70
	IBM AT 1984/1/10 BIOS ignores AL and always performs subfunction 00h
SeeAlso: AH=41h,AH=86h,INT 70,MEM 0040h:0098h,MEM 0040h:009Ch

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1584 - INT 15 - BIOS - JOYSTICK SUPPORT (XT after 1982/11/8,AT,XT286,PS)

INT 15 - BIOS - JOYSTICK SUPPORT (XT after 1982/11/8,AT,XT286,PS)
	AH = 84h
	DX = subfunction
	    0000h read joystick switches
		Return: AL bits 7-4 = switch settings
	    0001h read positions of joysticks
		Return: AX = X position of joystick A
			BX = Y position of joystick A
			CX = X position of joystick B
			DX = Y position of joystick B
Return: CF set on error
	    AH = status (see #00496)
	CF clear if successful
Notes:	if no game port is installed, subfunction 0000h returns AL=00h (all
	  switches open) and subfunction 0001h returns AX=BX=CX=DX=0000h
	a 250kOhm joystick typically returns 0000h-01A0h
SeeAlso: AH=84h"V20-XT-BIOS"

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1585 - INT 15 C - OS HOOK - SysReq KEY ACTIVITY (AT,PS)

INT 15 C - OS HOOK - SysReq KEY ACTIVITY (AT,PS)
	AH = 85h
	AL = SysReq key action (00h pressed, 01h released)
	CF clear
Return: CF clear if successful
	    AH = 00h
	CF set on error
	    AH = status (see #00496)
Notes:	called by keyboard decode routine
	the default handler simply returns successfully; programs which wish
	  to monitor the SysReq key must hook this call
	the SysReq key is often labeled SysRq
SeeAlso: INT 09

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1586 - INT 15 - BIOS - WAIT (AT,PS)

INT 15 - BIOS - WAIT (AT,PS)
	AH = 86h
	CX:DX = interval in microseconds
Return: CF clear if successful (wait interval elapsed)
	CF set on error or AH=83h wait already in progress
	    AH = status (see #00496)
Note:	the resolution of the wait period is 977 microseconds on many systems
	  because many BIOSes use the 1/1024 second fast interrupt from the AT
	  real-time clock chip which is available on INT 70; because newer
	  BIOSes may have much more precise timers available, it is not
	  possible to use this function accurately for very short delays unless
	  the precise behavior of the BIOS is known (or found through testing)
SeeAlso: AH=41h,AH=83h,INT 1A/AX=FF01h,INT 70

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1587 - INT 15 - SYSTEM - COPY EXTENDED MEMORY

INT 15 - SYSTEM - COPY EXTENDED MEMORY
	AH = 87h
	CX = number of words to copy (max 8000h)
	ES:SI -> global descriptor table (see #00499)
Return: CF set on error
	CF clear if successful
	AH = status (see #00498)
Notes:	copy is done in protected mode with interrupts disabled by the default
	  BIOS handler; many 386 memory managers perform the copy with
	  interrupts enabled
	on the PS/2 30-286 & "Tortuga" this function does not use the port 92h
	  for A20 control, but instead uses the keyboard controller (8042).
	  Reportedly this may cause the system to crash when access to the
	  8042 is disabled in password server mode (see also PORT 0064h,#P0398)
	this function is incompatible with the OS/2 compatibility box
SeeAlso: AH=88h,AH=89h,INT 1F/AH=90h

(Table 00498)
Values for extended-memory copy status:
 00h	source copied into destination
 01h	parity error
 02h	interrupt error
 03h	address line 20 gating failed
 80h	invalid command (PC,PCjr)
 86h	unsupported function (XT,PS30)

Format of global descriptor table:
Offset	Size	Description	(Table 00499)
 00h 16 BYTEs	zeros (used by BIOS)
 10h	WORD	source segment length in bytes (2*CX-1 or greater)
 12h  3 BYTEs	24-bit linear source address, low byte first
 15h	BYTE	source segment access rights (93h)
 16h	WORD	(286) zero
		(386+) extended access rights and high byte of source address
 18h	WORD	destination segment length in bytes (2*CX-1 or greater)
 1Ah  3 BYTEs	24-bit linear destination address, low byte first
 1Dh	BYTE	destination segment access rights (93h)
 1Eh	WORD	(286) zero
		(386+) extended access rights and high byte of destin. address
 20h 16 BYTEs	zeros (used by BIOS to build CS and SS descriptors)

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1588 - INT 15 - SYSTEM - GET EXTENDED MEMORY SIZE (286+)

INT 15 - SYSTEM - GET EXTENDED MEMORY SIZE (286+)
	AH = 88h
Return: CF clear if successful
	    AX = number of contiguous KB starting at absolute address 100000h
	CF set on error
	    AH = status
		80h invalid command (PC,PCjr)
		86h unsupported function (XT,PS30)
Notes:	TSRs which wish to allocate extended memory to themselves often hook
	  this call, and return a reduced memory size.	They are then free to
	  use the memory between the new and old sizes at will.
	the standard BIOS only returns memory between 1MB and 16MB; use AH=C7h
	  for memory beyond 16MB
	not all BIOSes correctly return the carry flag, making this call
	  unreliable unless one first checks whether it is supported through
	  a mechanism other than calling the function and testing CF
	Due to applications not dealing with more than 24-bit descriptors
	  (286), Windows 3.0 has problems when this function reports more
	  than 15 MB. Some releases of HIMEM.SYS are therefore limited to use
	  only 15 MB, even when this function reports more.
SeeAlso: AH=87h,AH=8Ah"Phoenix",AH=C7h,AX=DA88h,AX=E801h,AX=E820h

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1589 - INT 15 - SYSTEM - SWITCH TO PROTECTED MODE

INT 15 - SYSTEM - SWITCH TO PROTECTED MODE
	AH = 89h
	BL = interrupt number of IRQ0 (IRQ1-7 use next 7 interrupts)
	BH = interrupt number of IRQ8 (IRQ9-F use next 7 interrupts)
	ES:SI -> GDT for protected mode (see #00500)
Return: CF set on error
	   AH = FFh  error enabling address line 20
	CF clear if successful
	   AH = 00h
	   in protected mode at specified address
	   BP may be destroyed; all segment registers change
Notes:	BL and BH must be multiples of 8
	the protected-mode CS must reference the same memory as the CS this
	  function is called from because execution continues with the address
	  following the interrupt call
SeeAlso: AH=87h,AH=88h,INT 67/AX=DE0Ch

Format of BIOS switch-to-protected-mode Global Descriptor Table:
Offset	Size	Description	(Table 00500)
 00h  8 BYTEs	null descriptor (initialize to zeros)
 08h  8 BYTEs	GDT descriptor (see #00501)
 10h  8 BYTEs	IDT descriptor
 18h  8 BYTEs	DS descriptor
 20h  8 BYTEs	ES
 28h  8 BYTEs	SS
 30h  8 BYTEs	CS
 38h  8 BYTEs	uninitialized, used to build descriptor for BIOS CS

Format of segment descriptor table entry:
Offset	Size	Description	(Table 00501)
 00h	WORD	segment limit, low word
 02h  3 BYTEs	segment base address, low 24 bits
 05h	BYTE	access mode (see #00502)
 06h	BYTE	386+ extended access mode (see #00505)
 07h	BYTE	386+ segment base address, high 8 bits
SeeAlso: #00500,INT 2C/AX=0002h,INT 31/AX=0009h

Bitfields for segment descriptor table access mode field:
Bit(s)	Description	(Table 00502)
 3-0	segment type (see #00503,#00504)
 4	descriptor type (1 = application, 0 = system)
 6-5	descriptor privilege level
 7	segment is present in RAM
SeeAlso: #00501,#00505

(Table 00503)
Values for system segment descriptor type:
 0	reserved
 1	available 16-bit TSS
 2	LDT
 3	busy 16-bit TSS
 4	16-bit call gate
 5	task gate
 6	16-bit interrupt gate
 7	16-bit trap gate
 8	reserved
 9	available 32-bit TSS
 10	reserved
 11	busy 32-bit TSS
 12	32-bit call gate
 13	reserved
 14	32-bit interrupt gate
 15	32-bit trap gate
SeeAlso: #00502,#00504

Bitfields for application segment descriptor type:
Bit(s)	Description	(Table 00504)
 3	code/data
	0 date
	1 code
---data segments---
 2	expand down
 1	writeable
---code segments---
 2	conforming
 1	readable
------
 0	accessed
SeeAlso: #00502,#00503

Bitfields for 386+ segment descriptor table extended access mode field:
Bit(s)	Description	(Table 00505)
 3-0	high 4 bits of segment limit
 4	available
 5	reserved (0)
 6	default operation size (1 = 32 bits, 0 = 16 bits)
 7	granularity (1 = 4K, 0 = byte)
SeeAlso: #00501,#00502,#02557

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1590 - INT 15 - OS HOOK - DEVICE BUSY (AT,PS)

INT 15 - OS HOOK - DEVICE BUSY (AT,PS)
	AH = 90h
	AL = device type (see #00507)
	ES:BX -> request block for type codes 80h through BFh
	CF clear
Return: CF set if wait time satisfied
	CF clear if driver must perform wait
	    AH = 00h
Notes:	type codes are allocated as follows:
	  00-7F non-reentrant devices; OS must arbitrate access
	  80-BF reentrant devices; ES:BX points to a unique control block
	  C0-FF wait-only calls, no complementary INT 15/AH=91h call
	floppy and hard disk BIOS code uses this call to implement a timeout;
	  for device types 00h and 01h, a return of CF set means that the
	  timeout expired before the disk responded.
	this function should be hooked by a multitasker to allow other tasks
	  to execute while the BIOS is waiting for I/O completion; the default
	  handler merely returns with AH=00h and CF clear
SeeAlso: AH=91h,INT 13/AH=00h,INT 17/AH=00h,INT 1A/AH=83h

(Table 00507)
Values for device type:
 00h	disk
 01h	diskette
 02h	keyboard
 03h	PS/2 pointing device
 21h	waiting for keyboard input (Phoenix BIOS)
 80h	network
 FBh	digital sound (Tandy)
 FCh	disk reset (PS)
 FDh	diskette motor start
 FEh	printer

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1591 - INT 15 - OS HOOK - DEVICE POST (AT,PS)

INT 15 - OS HOOK - DEVICE POST (AT,PS)
	AH = 91h
	AL = device type (see #00507)
	ES:BX -> request block for type codes 80h through BFh
	CF clear
Return: AH = 00h
Note:	this function should be hooked by a multitasker to allow other tasks
	  to execute while the BIOS is waiting for I/O completion; the default
	  handler merely returns with AH=00h and CF clear
SeeAlso: AH=90h

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1592 - INT 15 - IBM SurePath BIOS - Officially "Private" Function

INT 15 - IBM SurePath BIOS - Officially "Private" Function
	AH = 92h
SeeAlso: AH=07h"IBM",AH=3Eh"IBM"

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15A0 - INT 15 - IBM SurePath BIOS - ACCESS LOADABLE-ABIOS SIGNATURE

INT 15 - IBM SurePath BIOS - ACCESS LOADABLE-ABIOS SIGNATURE
	AH = A0h
	AL = function
	    00h get loadable-ABIOS signature
		Return: BL = signature value
			    00h loadable-ABIOS prompting not required
			    A1h loadable-ABIOS prompting is required
	    01h write loadable-ABIOS signature
		BL = new signature value
		    00h loadable-ABIOS prompting not required
		    A1h loadable-ABIOS prompting is required
Return: CF clear if successful
	CF set on error
	AH = status
	    00h successful
	    01h invalid subfunction
	    02h unable to read/write signature
	    86h function not supported
Note:	IBM classifies this function as optional
SeeAlso: AH=08h"IBM"

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15AB - INT 15 - IBM SurePath BIOS - Officially "Private" Function

INT 15 - IBM SurePath BIOS - Officially "Private" Function
	AH = ABh
SeeAlso: AH=07h"IBM",AH=3Eh"IBM"

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15C0 - INT 15 - SYSTEM - GET CONFIGURATION (XT >1986/1/10,AT mdl 3x9,CONV,XT286,PS)

INT 15 - SYSTEM - GET CONFIGURATION (XT >1986/1/10,AT mdl 3x9,CONV,XT286,PS)
	AH = C0h
Return: CF set if BIOS doesn't support call
	CF clear on success
	    ES:BX -> ROM table (see #00509)
	AH = status
	    00h successful
		The PC XT (since 1986/01/10), PC AT (since 1985/06/10), the
		  PC XT Model 286, the PC Convertible and most PS/2 machines
		  will clear the CF flag and return the table in ES:BX.
	    80h unsupported function
		The PC and PCjr return AH=80h/CF set
	    86h unsupported function
		The PC XT (1982/11/08), PC Portable, PC AT (1984/01/10),
		or PS/2 prior to Model 30 return AH=86h/CF set
Notes:	the 1986/1/10 XT BIOS returns an incorrect value for the feature byte
	the configuration table is at F000h:E6F5h in 100% compatible BIOSes
	Dell machines contain the signature "DELL" or "Dell" at absolute FE076h
	  and a model byte at absolute address FE845h (see #00516)
	Hewlett-Packard machines contain the signature "HP" at F000h:00F8h and
	  a product identifier at F000h:00FAh (see #00519)
	Compaq machines can be identified by the signature string "COMPAQ" at
	  F000h:FFEAh, and is preceded by additional information (see #00517)
	Tandy 1000 machines contain 21h in the byte at F000h:C000h and FFh in
	  the byte at FFFFh:000Eh; Tandy 1000SL/TL machines only provide the
	  first three data bytes (model/submodel/revision) in the returned
	  table
	the ID at F000h:C000h is used by some Microsoft software before
	  trusting the floppy flags bits 1 and 0 at 0040h:00B5h.
	the Wang PC contains the signature "WANG" at FC00h:0000h. This is used
	  by Peter Reilley's portable binary editor and viewer BEAV to detect
	  a Wang PC.
	Toshiba laptops contain the signature "TOSHIBA" at FE010h as part of
	  a laptop information record at F000h:E000h (see #00520)
	some AST machines contain the string "COPYRIGHT AST RESEARCH" one byte
	  past the end of the configuration table
	the Phoenix 386 BIOS contains a second version and date string
	  (presumably the last modification for that OEM version) beginning at
	  F000h:FFD8h, with each byte doubled (so that both ROM chips contain
	  the complete information)
SeeAlso: AH=C7h,AH=C9h,AX=D100h,AX=D103h

Format of ROM configuration table:
Offset	Size	Description	(Table 00509)
 00h	WORD	number of bytes following
 02h	BYTE	model (see #00515)
 03h	BYTE	submodel (see #00515)
 04h	BYTE	BIOS revision: 0 for first release, 1 for 2nd, etc.
 05h	BYTE	feature byte 1 (see #00510)
 06h	BYTE	feature byte 2 (see #00511)
 07h	BYTE	feature byte 3 (see #00512)
 08h	BYTE	feature byte 4 (see #00513)
 09h	BYTE	feature byte 5 (see #00514)
		??? (08h) (Phoenix 386 v1.10)
		??? (0Fh) (Phoenix 486 v1.03 PCI)
---AWARD BIOS---
 0Ah  N BYTEs	AWARD copyright notice
---Phoenix BIOS---
 0Ah	BYTE	??? (00h)
 0Bh	BYTE	major version
 0Ch	BYTE	minor version (BCD)
 0Dh  4 BYTEs	ASCIZ string "PTL" (Phoenix Technologies Ltd)
		also on Phoenix Cascade BIOS
---Quadram Quad386---
 0Ah 17 BYTEs	ASCII signature string "Quadram Quad386XT"
---Toshiba (Satellite Pro 435CDS at least)---
 0Ah  7 BYTEs	signature "TOSHIBA"
 11h	BYTE	??? (8h)
 12h	BYTE	??? (E7h) product ID??? (guess)
 13h  3 BYTEs	"JPN"

Bitfields for feature byte 1:
Bit(s)	Description	(Table 00510)
 7	DMA channel 3 used by hard disk BIOS
 6	2nd interrupt controller (8259) installed
 5	Real-Time Clock installed
 4	INT 15/AH=4Fh called upon INT 09h
 3	wait for external event (INT 15/AH=41h) supported
 2	extended BIOS area allocated (usually at top of RAM)
 1	bus is Micro Channel instead of ISA
 0	system has dual bus (Micro Channel + ISA)
SeeAlso: #00509,#00511

Bitfields for feature byte 2:
Bit(s)	Description	(Table 00511)
 7	32-bit DMA supported
 6	INT 16/AH=09h (keyboard functionality) supported (see #00585)
 5	INT 15/AH=C6h (get POS data) supported
 4	INT 15/AH=C7h (return memory map info) supported
 3	INT 15/AH=C8h (en/disable CPU functions) supported
 2	non-8042 keyboard controller
 1	data streaming supported
 0	reserved
SeeAlso: #00509,#00512,AH=C6h,AH=C7h,AH=C8h,INT 16/AH=09h

Bitfields for feature byte 3:
Bit(s)	Description	(Table 00512)
 7	not used
 6-5	reserved
 4	POST supports ROM-to-RAM enable/disable
 3	SCSI subsystem supported on system board
 2	information panel installed
 1	IML (Initial Machine Load) system (BIOS loaded from disk)
 0	SCSI supported in IML
SeeAlso: #00509,#00511,#00512

Bitfields for feature byte 4:
Bit(s)	Description	(Table 00513)
 7	IBM "private" (set on N51SX, CL57SX)
 6	system has EEPROM
 5-3	ABIOS presence
	001 not supported
	010 supported in ROM
	011 supported in RAM (must be loaded)
 2	"private"
 1	system supports memory split at/above 16M
 0	POSTEXT directly supported by POST
SeeAlso: #00509,#00512,#00514

Bitfields for feature byte 5 (IBM):
Bit(s)	Description	(Table 00514)
 7-5	IBM "private"
 4-2	reserved
 1	system has enhanced mouse mode
 0	flash EPROM
SeeAlso: #00509,#00513

(Table 00515)
Values for model/submodel/revision:
Model  Submdl  Rev	BIOS date	System
 FFh	*	*	04/24/81	PC (original)
 FFh	*	*	10/19/81	PC (some bugfixes)
 FFh	*	*	10/27/82	PC (HD, 640K, EGA support)
 FFh	00h	rev	  ???		Tandy 1000SL
 FFh	01h	rev	  ???		Tandy 1000TL
 FFh	46h	***	  ???		Olivetti M15
 FEh	*	*	08/16/82	PC XT
 FEh	*	*	11/08/82	PC XT and Portable
 FEh	*	*	../..x..	Toshiba laptops up to ~1987
					("x"=product ID) (see #00521)
 FEh	00h	*** *	  ???		Olivetti M19
 FEh	43h	***	  ???		Olivetti M240
 FEh	A6h	???	  ???		Quadram Quad386
 FDh	*	*	06/01/83	PCjr
 FCh	*	*	01/10/84	AT models 068,099 6 MHz 20MB
 FCh	*	*	02/25/93	Linux DOSEMU (all versions)
 FCh	00h	00h	  ???		PC3270/AT
 FCh	00h	01h	06/10/85	AT model  239	  6 MHz 30MB
 FCh	00h	> 01h	  ???		7531/2 Industrial AT
 FCh	01h	00h	11/15/85	AT models 319,339 8 MHz, Enh Keyb, 3.5"
 FCh	01h	00h	09/17/87	Tandy 3000
 FCh	01h	00h	../..x..	Toshiba laptops since ~1988
					("x"=product ID) (see #00521)
 FCh	01h	00h	03/08/93	Compaq DESKPRO/i
 FCh	01h	00h	 various	Compaq DESKPRO, SystemPro, ProSignia
 FCh	01h	00h	07/20/93	Zenith Z-Lite 425L
 FCh	01h	00h	04/09/90	AMI BIOS
 FCh	01h	20h	06/10/92	AST
 FCh	01h	30h	  ???		Tandy 3000NL
 FCh	01h	???	  ???		Compaq 286/386
 FCh	02h	00h	04/21/86	PC XT-286
 FCh	02h	00h	 various	Compaq LTE Lite
 FCh	02h	00h	08/05/93	Compaq Contura 486/486c/486cx
 FCh	02h	00h	08/11/88	SoftWindows 1.0.1 (Power Macintosh)
 FCh	04h	00h	02/13/87     ** PS/2 Model 50 (10 MHz/1 ws 286)
 FCh	04h	01h	05/09/87	PS/2 Model 50 (10 Mhz 286, LW-type 32)
 FCh	04h	02h	  ???		PS/2 Model 50
 FCh	04h	02h	01/28/88	PS/2 Model 50Z (10 Mhz 286, LW-type 33)
 FCh	04h	03h	04/18/88	PS/2 Model 50Z (10 MHz/0 ws 286)
 FCh	04h	04h	  ???		PS/2 Model 50Z
 FCh	05h	00h	02/13/87     ** PS/2 Model 60 (10 MHz 286)
 FCh	06h	00h	  ???		IBM 7552-140 "Gearbox"
 FCh	06h	01h	  ???		IBM 7552-540 "Gearbox"
 FCh	08h	***	  ???		Epson, unknown model
 FCh	08h	00h	  ???		PS/2 Model 25/286
 FCh	09h	00h	  ???		PS/2 Model 25 (10 MHz 286)
 FCh	09h	00h	08/25/88	PS/2 Model 30 286 (10 Mhz, LW-type 37)
 FCh	09h	02h	06/28/89	PS/2 Model 30-286
 FCh	09h	02h	06/28/89	PS/2 Model 25 286 (10 Mhz, LW-type 37)
 FCh	0Bh	00h	12/01/89	PS/1 (LW-Type 44)
 FCh	0Bh	00h	02/16/90	PS/1 Model 2011 (10 MHz 286)
 FCh	20h	00h	02/18/93	Compaq ProLinea
 FCh	25h	09h	12/07/91	PS/2 Model 56 SLC (20 MHz 386SLC)
 FCh	30h	***	  ???		Epson, unknown model
 FCh	31h	***	  ???		Epson, unknown model
 FCh	33h	***	  ???		Epson, unknown model
 FCh	42h	***	  ???		Olivetti M280
 FCh	45h	***	  ???		Olivetti M380 (XP 1, XP3, XP 5)
 FCh	48h	***	  ???		Olivetti M290
 FCh	4Fh	***	  ???		Olivetti M250
 FCh	50h	***	  ???		Olivetti M380 (XP 7)
 FCh	51h	***	  ???		Olivetti PCS286
 FCh	52h	***	  ???		Olivetti M300
 FCh	81h	00h	01/15/88	Phoenix 386 BIOS v1.10 10a
 FCh	81h	01h	  ???		"OEM machine"
 FCh	82h	01h	  ???		"OEM machine"
 FCh	94h	00h	  ???		Zenith 386
 FBh	00h	01h	01/10/86	PC XT-089, Enh Keyb, 3.5" support
 FBh	00h	01h	05/13/94	HP 200LX 2MB BIOS 1.01 A D german
 FBh	00h	02h	05/09/86	PC XT
 FBh	00h	04h	08/19/93	HP 100LX 1MB BIOS 1.04 A
 FBh	4Ch	***	  ???		Olivetti M200
 FAh	00h	00h	09/02/86	PS/2 Model 30 (8 MHz 8086)
 FAh	00h	01h	12/12/86	PS/2 Model 30
 FAh	00h	02h	02/05/87	PS/2 Model 30
 FAh	01h	00h	06/26/87	PS/2 Model 25/25L (8 MHz 8086)
 FAh	30h	00h	  ???		IBM Restaurant Terminal
 FAh	4Eh	***	  ???		Olivetti M111
 FAh	FEh	00h	  ???		IBM PCradio 9075
 F9h	00h	00h	09/13/85	PC Convertible
 F9h	FFh	00h	  ???		PC Convertible
 F8h	00h	00h	03/30/87     ** PS/2 Model 80 (16MHz 386)
 F8h	00h	00h	  ???		PS/2 Model 75 486 (33Mhz 486)
 F8h	01h	00h	10/07/87	PS/2 Model 80 (20MHz 386)
 F8h	02h	00h	  ???		PS/2 Model 55-5571
 F8h	04h	00h	01/29/88	PS/2 Model 70 (20 Mhz 386DX,LW-type 33)
 F8h	04h	02h	04/11/88	PS/2 Model 70 20MHz, type 2 system brd
 F8h	04h	03h	03/17/89	PS/2 Model 70 20MHz, type 2 system brd
 F8h	05h	00h	  ???		IBM PC 7568
 F8h	06h	00h	  ???		PS/2 Model 55-5571
 F8h	07h	00h	  ???		IBM PC 7561/2
 F8h	07h	01h	  ???		PS/2 Model 55-5551
 F8h	07h	02h	  ???		IBM PC 7561/2
 F8h	07h	03h	  ???		PS/2 Model 55-5551
 F8h	09h	00h	01/29/88	PS/2 Model 70 16MHz 386DX, type 1 sysbd
 F8h	09h	02h	04/11/88	PS/2 Model 70 some models
 F8h	09h	03h	03/17/89	PS/2 Model 70 some models
 F8h	09h	04h	12/15/89	PS/2 Model 70 (16 Mhz 386, LW-type 33)
 F8h	0Bh	00h	01/18/89	PS/2 Model P70 (8573-121) typ 2 sys brd
 F8h	0Bh	02h	12/16/89	PS/2 Model P70 ??
 F8h	0Ch	00h	11/02/88	PS/2 Model 55SX (16 MHz 386SX)
 F8h	0Dh	00h	  ???		PS/2 Model 70 25MHz, type 3 system brd
 F8h	0Dh	00h	06/08/88	PS/2 Model 70 386 25MHz, type 3 sys brd
 F8h	0Dh	01h	02/20/89	PS/2 Model 70 386 25MHz, type 3 sys brd
 F8h	0Dh	???	12/01/89	PS/2 Model 70 486 25Mhz, type 3 sys brd
 F8h	0Eh	00h	  ???		PS/1 486SX
 F8h	0Fh	00h	  ???		PS/1 486DX
 F8h	10h	00h	  ???		PS/2 Model 55-5551
 F8h	11h	00h	10/01/90	PS/2 Model 90 XP (25 MHz 486)
 F8h	12h	00h	  ???		PS/2 Model 95 XP
 F8h	13h	00h	10/01/90	PS/2 Model 90 XP (33 MHz 486)
 F8h	14h	00h	10/01/90	PS/2 Model 90-AK9 (25 MHz 486), 95 XP
 F8h	15h	00h	  ???		PS/2 Model 90 XP
 F8h	16h	00h	10/01/90	PS/2 Model 90-AKD / 95XP486 (33MHz 486)
 F8h	17h	00h	  ???		PS/2 Model 90 XP
 F8h	19h	05h	  ???		PS/2 Model 35/35LS or 40 (20 MHz 386SX)
 F8h	19h	05h	03/15/91	PS/2 Model 35 SX / 40 SX (LW-type 37)
 F8h	19h	06h	04/04/91	PS/2 Model 35 SX / 40 SX (LW-type 37)
 F8h	1Ah	00h	  ???		PS/2 Model 95 XP
 F8h	1Bh	00h	09/29/89	PS/2 Model 70 486 (25 Mhz 386DX)
 F8h	1Bh	00h	10/02/89	PS/2 Model 70-486 (25 MHz 486)
 F8h	1Ch	00h	02/08/90	PS/2 Model 65-121 / 65 SX (16MHz 386SX)
 F8h	1Eh	00h	02/08/90	PS/2 Model 55LS (16 MHz 386SX)
 F8h	23h	00h	  ???		PS/2 Model L40 SX
 F8h	23h	01h	  ???		PS/2 Model L40 SX (20 MHz 386SX)
 F8h	23h	02h	02/27/91	PS/2 Model L40 SX (20Mhz386SX,LW-typ37)
 F8h	25h	00h	  ???		PS/2 Model 57 SLC
 F8h	25h	06h	  ???		PS/2 Model M57 (20 MHz 386SLC)
 F8h	26h	00h	  ???		PS/2 Model 57 SX
 F8h	26h	01h	  ???		PS/2 Model 57 (20 MHz 386SX)
 F8h	26h	02h	07/03/91	PS/2 Model 57 SX (20Mhz 386SX, SCSI)
 F8h	28h	00h	  ???		PS/2 Model 95 XP
 F8h	29h	00h	  ???		PS/2 Model 90 XP
 F8h	2Ah	00h	  ???		PS/2 Model 95 XP (50 MHz 486)
 F8h	2Bh	00h	  ???		PS/2 Model 90 / 90XP486 (50 MHz 486)
 F8h	2Ch	00h	  ???		PS/2 Model 95 XP
 F8h	2Ch	01h	  ???		PS/2 Model 95 (20 MHz 486SX)
 F8h	2Dh	00h	  ???		PS/2 Model 90 XP (20 MHz 486SX)
 F8h	2Eh	00h	  ???		PS/2 Model 95 XP
 F8h	2Eh	00h	  ???		PS/2 Model 95 XP486 (20 Mhz 486SX)
 F8h	2Eh	01h	  ???		PS/2 Model 95 (20 MHz 486SX + 487SX)
 F8h	2Fh	00h	  ???		PS/2 Model 90 XP (20 MHz 486SX + 487SX)
 F8h	30h	00h	  ???		PS/1 Model 2121 (16 MHz 386SX)
 F8h	33h	00h	  ???		PS/2 Model 30-386
 F8h	34h	00h	  ???		PS/2 Model 25-386
 F8h	36h	00h	  ???		PS/2 Model 95 XP
 F8h	37h	00h	  ???		PS/2 Model 90 XP
 F8h	38h	00h	  ???		PS/2 Model 57
 F8h	39h	00h	  ???		PS/2 Model 95 XP
 F8h	3Fh	00h	  ???		PS/2 Model 90 XP
 F8h	40h	00h	  ???		PS/2 Model 95 XP
 F8h	41h	00h	  ???		PS/2 Model 77
 F8h	45h	00h	  ???		PS/2 Model 90 XP (Pentium)
 F8h	46h	00h	  ???		PS/2 Model 95 XP (Pentium)
 F8h	47h	00h	  ???		PS/2 Model 90/95 E (Pentium)
 F8h	48h	00h	  ???		PS/2 Model 85
 F8h	49h	00h	  ???		PS/ValuePoint 325T
 F8h	4Ah	00h	  ???		PS/ValuePoint 425SX
 F8h	4Bh	00h	  ???		PS/ValuePoint 433DX
 F8h	4Eh	00h	  ???		PS/2 Model 295
 F8h	50h	00h	  ???		PS/2 Model P70 (8573) (16 MHz 386)
 F8h	50h	01h	12/16/89	PS/2 Model P70 (8570-031)
 F8h	52h	00h	  ???		PS/2 Model P75 (33 MHz 486)
 F8h	56h	00h	  ???		PS/2 Model CL57 SX
 F8h	57h	00h	  ???		PS/2 Model 90 XP
 F8h	58h	00h	  ???		PS/2 Model 95 XP
 F8h	59h	00h	  ???		PS/2 Model 90 XP
 F8h	5Ah	00h	  ???		PS/2 Model 95 XP
 F8h	5Bh	00h	  ???		PS/2 Model 90 XP
 F8h	5Ch	00h	  ???		PS/2 Model 95 XP
 F8h	5Dh	00h	  ???		PS/2 Model N51 SLC
 F8h	5Eh	00h	  ???		IBM ThinkPad 700
 F8h	61h	***	  ???		Olivetti P500
 F8h	62h	***	  ???		Olivetti P800
 F8h	80h	00h	  ???		PS/2 Model 80 (25 MHz 386)
 F8h	80h	01h	11/21/89	PS/2 Model 80-A21 (25 Mhz 386)
 F8h	81h	00h	  ???		PS/2 Model 55-5502
 F8h	87h	00h	  ???		PS/2 Model N33SX
 F8h	88h	00h	  ???		PS/2 Model 55-5530T
 F8h	97h	00h	  ???		PS/2 Model 55 Note N23SX
 F8h	99h	00h	  ???		PS/2 Model N51 SX
 F8h	F2h	30h	  ???		Reply Model 32
 F8h	F6h	30h	  ???		Memorex Telex
 F8h	FDh	00h	  ???		IBM Processor Complex (with VPD)
 F8h	???	???	  ???		PS/2 Model 90 (25 MHz 486SX)
 F8h	???	???	  ???		PS/2 Model 95 (25 MHz 486SX)
 F8h	???	???	  ???		PS/2 Model 90 (25 MHz 486SX + 487SX)
 F8h	???	???	  ???		PS/2 Model 95 (25 MHz 486SX + 487SX)
 E4h	???	???	  ???		Triumph Adler PC/XT
 E1h	???	???	  ???		??? (checked for by DOS4GW.EXE)
 E1h	00h	00h	  ???		PS/2 Model 55-5530 Laptop
 D9h	???	???	  ???		Peacock XT
 9Ah	*	*	  ???		Compaq XT/Compaq Plus
 30h	???	???	  ???		Sperry PC
 2Dh	*	*	  ???		Compaq PC/Compaq Deskpro
 ???	56h	???	  ???		Olivetti, unknown model
 ???	74h	???	  ???		Olivetti, unknown model
Notes:	BIOS dates may vary without changes to the revision code, especially
	  for non-IBM machines
    * This BIOS call is not implemented in these early versions or under
      Linux's DOSEMU.  Read the Model byte at F000h:FFFEh and BIOS date at
      F000h:FFF5h instead.
   ** These BIOS versions require the DASDDRVR.SYS patches.
  *** These Olivetti and Epson machines store the submodel in the byte at
	F000h:FFFDh.
SeeAlso: #00509,#00516

(Table 00516)
Values for Dell model byte:
 02h	Dell 200
 03h	Dell 300
 05h	Dell 220
 06h	Dell 310
 07h	Dell 325
 09h	Dell 310A
 0Ah	Dell 316
 0Bh	Dell 220E
 0Ch	Dell 210
 0Dh	Dell 316SX
 0Eh	Dell 316LT
 0Fh	Dell 320LX
 11h	Dell 425E
SeeAlso: #00509,#00515

Format of Compaq product information:
Address		Size	Description	(Table 00517)
 F000h:FFE4h	BYTE	product family code (first byte)
 F000h:FFE5h	BYTE	Point release number
 F000h:FFE6h	BYTE	ROM version code
 F000h:FFE7h	BYTE	product family code (second byte)
 F000h:FFE8h	WORD	BIOS type code
SeeAlso: #00518,#00520

Format of Hewlett-Packard ROM ID at F000h:00F8h:
Offset	Size	Description	(Table 00518)
 00h  2 BYTEs	signature "HP" (48h 50h)
 02h  2 BYTEs	00h 00h
 04h	BYTE	secondary code revision
 05h	BYTE	primary code revision
 06h	BYTE	date code, year-1960 (BCD)
 07h	BYTE	date code, week of year (BCD)
SeeAlso: #00517,#00519

Bitfields for Hewlett-Packard product identifier:
Bit(s)	Description	(Table 00519)
 4-0	machine code
	0 original Vectra
	1 ES/12
	2 RS/20
	3 Portable/CS
	4 ES
	5 CS
	6 RS/16
	other reserved
 7-5	CPU type
	0 = 80286
	1 = 8088
	2 = 8086
	3 = 80386
	other reserved
SeeAlso: #00518

Format of Toshiba laptop information:
Offset	Size	Description	(Table 00520)
 00h  8 BYTEs	ASCII product number (e.g. "T2200SX ")
 08h  8 BYTEs	ASCII version number (e.g. "V1.20   ")
 10h  8 BYTEs	ASCII signature string "TOSHIBA "
 18h  8 BYTEs	always zero???
 20h	DWORD	-> built-in BIOS setup program entry point or 0000h:0000h
Note:	this record is located at F000h:E000h
SeeAlso: #00517,#00518

(Table 00521)
Values for Toshiba product ID:
model prodID   version	  date	   product number
 FEh	29h		../..)..   Toshiba T1000LE
 FEh	2Ah		../..*..   Toshiba T1000XE
 FEh	2Bh		../..+..   Toshiba T1000SE
 FEh	2Ch		../..,..   Toshiba T1000
 FEh	2Dh		../..-..   Toshiba T1200F
 FEh	2Dh	V4.00	12/26-87   Toshiba T1200H
 FEh	2Eh		../.....   Toshiba T1100+
 FCh	22h		../.."..   Toshiba T8500
 FCh	26h		01/15&88   Toshiba T5200
 FCh	27h		../..'..   Toshiba T5100
 FCh	28h		../..(..   Toshiba T2000
 FCh	2Ah		12/26*89   Toshiba T1200XE
 FCh	2Bh		../..+..   Toshiba T1600
 FCh	2Ch		../..,..   Toshiba T3100e
 FCh	2Dh		../..-..   Toshiba T3200
 FCh	2Fh		../../..   Toshiba T3100
 FCh	34h	V1.50	02/04494   Toshiba T100X
 FCh	38h		../..8..   Toshiba T2000SXe
 FCh	39h	V1.20	09/16991   Toshiba T2200SX
 FCh	39h	V1.40	10/01992   Toshiba T2200SX
 FCh	3Ch	V1.50	01/28<91   Toshiba T2000SX
 FCh	3Dh		../..=..   Toshiba T3200SXC
 FCh	3Eh		../..>..   Toshiba T3100SX
 FCh	3Fh		../..?..   Toshiba T3200SX
 FCh	40h		../..@..   Toshiba T4500C
 FCh	41h	V1.20	04/05A92   Toshiba T4500     ("T4500SXC" ???)
 FCh	45h	V3.20	04/14E92   Toshiba T4400SX   ("C" or "SXC" on cover)
 FCh	45h		01/13E93   Toshiba T4400SXC
 FCh	46h *		../..F..   Toshiba T6400
 FCh	46h *		../..F..   Toshiba T6400C
 FCh	5Fh	V1.40	01/18_94   Toshiba T3300SL
 FCh	69h		../..i..   Toshiba T1900C    ("T1900CT" ???)
 FCh	6Ah	V1.30	05/19j93   Toshiba T1900     ("T1900S" ???)
 FCh	6Dh	V1.10	12/25m92   Toshiba T1850C
 FCh	6Eh	V1.00	08/19n92   Toshiba T1850
 FCh	6Eh	V1.10	12/25n92   Toshiba T1850
 FCh	6Fh	V1.00	07/17o92   Toshiba T1800
 FCh	6Fh	V1.10	12/25o92   Toshiba T1800
 FCh	7Eh	V1.30	06/17~93   Toshiba T4600C
 FCh	7Fh	V1.40	11/10x94   Toshiba T4600
 FCh	8Ah	V1.30	10/22x93   Toshiba T6600C
 FCh	91h	V1.20	07/15x94   Toshiba T2400CT
 FCh	91h	V5.00	07/28x95   Toshiba T2400CS/CT
 FCh	92h	V5.00	07/28x95   Toshiba T3600CT
 FCh	96h *	V1.40	12/08x94   Toshiba T200
 FCh	96h *	V1.50	12/08x94   Toshiba T200CS	(T200)
 FCh	97h		../..x..   Toshiba T4800CT
 FCh	98h *	V1.10	12/22x93   Toshiba T1910
 FCh	98h *	V2.40	07/12x94   Toshiba T1910/CS	(T19XX)
 FCh	99h		../..x..   Toshiba T4700CS
 FCh	9Bh	V2.30	01/31x94   Toshiba T4700CT
 FCh	9Bh	V2.50	03/22x94   Toshiba T4700CT
 FCh	9Bh	V5.00	07/28x95   Toshiba T4700CT
 FCh	9Ch	V1.30	01/11x94   Toshiba T1950CT
 FCh	9Ch	V2.50	07/22x94   Toshiba T1950CT	(T19XX)
 FCh	9Dh *	V2.40	07/12x94   Toshiba T1950/CS	(T19XX)
 FCh	9Eh *	V1.20	12/25x93   Toshiba T3400
 FCh	9Eh *	V1.30	03/22x94   Toshiba T3400/CT
 FCh	B5h **	V5.10	08/25x95   Toshiba T2110/CS	(T21XX)
 FCh	B5h	V5.10	08/25x95   Toshiba T2130CS/CT	(T21XX)
 FCh	BAh	V1.30	02/16x95   Toshiba T2150CDS/CDT
 FCh	BAh	V5.00	07/27x95   Toshiba T2150CDS/CDT (T2150)
 FCh	BBh **	V1.30	01/25x95   Toshiba T2100/CS/CT
 FCh	BBh **	V5.00	07/27x95   Toshiba T2100/CS/CT
 FCh	BCh	V1.20	12/05x94   Toshiba T2450CT
 FCh	BCh	V5.00	07/28x95   Toshiba T2450CT
 FCh	BEh	V5.00	07/28x95   Toshiba T4850CT
 FCh	C0h	V5.20	05/30x96   Toshiba 420CDS/CDT
 FCh	C1h	V5.20	03/27x96   Toshiba 100CS
 FCh	C3h	V5.60	07/19x96   Toshiba 710CDT / 720CDT
 FCh	C6h	V5.30	11/30x95   Toshiba 410CS/CDT
 FCh	CAh	V5.10	08/18x95   Toshiba 400CS/CDT
 FCh	CAh	V5.40	12/18x95   Toshiba 400CS/CDT
 FCh	CBh	V5.10	09/01x95   Toshiba 610CT
 FCh	CCh	V5.50	06/13x96   Toshiba 700CS/CT
 FCh	CFh	V5.00	08/07x95   Toshiba T4900CT
 FCh	DCh	V5.10	06/17x96   Toshiba 650CT
 FCh	DCh	V5.10	05/10x96   Toshiba 110CS/CT
 FCh	DDh	V5.10	05/10x96   Toshiba 110CS/CT
 FCh	DFh	V5.20	05/27x96   Toshiba 500CS/CDT
 FCh	???	V5.???	../..x..   Toshiba 620CT
 FCh	???	V5.???	../..x..   Toshiba 660CDT
 FCh	???	V5.30	11/22/96   Toshiba 730CDT
 FCh	???	V6.00	09/20/96   Toshiba 200CDS/CDT
 FCh	???	V6.20	11/14/96   Toshiba 430CDS/CDT
 FCh	???	V6.40	12/05/96   Toshiba 510CS/CDT
Notes:	the 8-bit ASCII graphics character in the "date" column above
	  has been substituted by "x" if larger than 80h
	BIOS version numbers and dates may vary, esp. due to harddisk and
	  (flash) BIOS upgrades; all BIOS versions 5.xx are flash updates
	  for Windows95, the product number may indicate the series only
	  (T21XX) or does no longer contain the exact type suffix (CS/CT)
	the most recent versions of the BIOS have stopped including the
	  product ID code in the BIOS date
	[*] These models have monochrome and color versions which can be
	  distinguished with INT 42/AX=7503h (WD90C24 chipset)
	[**] These models have monochrome and color versions which can be
	  distinguished with INT 10/AX=5F50h (CT655xx chipset)
	models not found here like T21x5 are variants differing only in
	  bundled software
SeeAlso: #00515

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15C1 - INT 15 - SYSTEM - RETURN EXTENDED-BIOS DATA-AREA SEGMENT ADDRESS (PS)

INT 15 - SYSTEM - RETURN EXTENDED-BIOS DATA-AREA SEGMENT ADDRESS (PS)
	AH = C1h
Return: CF set on error
	CF clear if successful
	    ES = segment of data area (see #M0001,#M0004,#M0005)
SeeAlso: AH=04h"ABIOS",MEM 0040h:000Eh"DATA"

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15C3 - INT 15 - SYSTEM - ENABLE/DISABLE WATCHDOG TIMEOUT (PS50+)

INT 15 - SYSTEM - ENABLE/DISABLE WATCHDOG TIMEOUT (PS50+)
	AH = C3h
	AL = function
	    00h disable PS/2 watchdog timer
	    01h enable PS/2 watchdog timer
		BX = timer counter (0001h-00FFh)
	    02h disable Gearbox system
	    03h enable Gearbox system
Return: CF set on error
	CF clear if successful
Note:	the watchdog timer generates an NMI
SeeAlso: INT 21/AH=2Bh/CX=6269h"WDTSR"

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15C4 - INT 15 - SYSTEM - PROGRAMMABLE OPTION SELECT (PS50+)

INT 15 - SYSTEM - PROGRAMMABLE OPTION SELECT (PS50+)
	AH = C4h
	AL = subfunction
	    00h return base POS register address
	    01h enable selected slot for setup
		BL = slot number (1 to 8)
	    02h disable setup for all slots (enable adapter)
Return: CF set on error
	DX = base POS register address (if subfunction 00h)
SeeAlso: AH=C6h

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15C5 - INT 15 UC - OS HOOK - ROM BIOS TRACING CALLOUT (PS30/286,PS50Z,PS95)

INT 15 UC - OS HOOK - ROM BIOS TRACING CALLOUT (PS30/286,PS50Z,PS95)
	AH = C5h
	AL = interrupt being invoked
	    01h INT 19
	    02h INT 14
	    03h INT 16
	    04h INT 40 (floppy INT 13)
	    05h INT 17
	    06h INT 10
	    07h INT 12
	    08h INT 11
	    09h INT 1A
Return: all registers except AX must be preserved
Notes:	called as the very first action of the indicated ROM BIOS interrupt
	  handlers on the PS/2 Models 30/286, 50Z, and 95
	default handler does nothing and returns CF clear for the above
	  subfunctions, CF set and AH=86h for all other subfunctions
	value of AX passed to the original interrupt handler is pushed on
	  stack immediately prior to call

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15C6 - INT 15 U - later PS/2 models - GET POS DATA

INT 15 U - later PS/2 models - GET POS DATA
	AH = C6h
	???
Return: ???
Notes:	this function is referenced by name and number in some IBM BIOS manuals
	IBM reports that "there are a number of problems with this call" and
	  does not recommend its use.
SeeAlso: AH=C4h

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15C7 - INT 15 - SYSTEM - later PS/2s - RETURN MEMORY-MAP INFORMATION

INT 15 - SYSTEM - later PS/2s - RETURN MEMORY-MAP INFORMATION
	AH = C7h
	DS:SI -> user supplied memory map table (see #00526)
Return: CF set on error
	CF clear if successful
Notes:	call AH=C0h and examine bit 4 of feature byte 2 to check if this
	  function is supported
	IBM classifies this function as optional
	Windows95 OSR2 reportedly does not support this function even though
	  INT 15/AH=C0h indicates that it is available (observed on several
	  different systems)
SeeAlso: AH=C0h,AH=C9h,AH=D1h,AX=E820h

Format of memory-map table structure:
Offset	Size	Description	(Table 00526)
 00h	WORD	length of table (excluding this word)
 02h	DWORD	local memory between 1M and 16M, in 1K blocks
 06h	DWORD	local memory between 16M and 4G, in 1K blocks
 0Ah	DWORD	system memory between 1M and 16M, in 1K blocks
 0Eh	DWORD	system memory between 16M and 4G, in 1K blocks
 12h	DWORD	cacheable memory between 1M and 16M, in 1K blocks
 16h	DWORD	cacheable memory between 16M and 4G, in 1K blocks
 1Ah	DWORD	1K blocks before start of non-system memory between 1M and 16M
 1Eh	DWORD	1K blocks before start of non-system memory between 16M and 4G
 22h	WORD	start segment of largest free block from C0000h-DFFFFh
 24h	WORD	size of largest free block
 26h	DWORD	reserved

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15C8 - INT 15 - SYSTEM - ENABLE/DISABLE PROCESSOR FUNCTIONS

INT 15 - SYSTEM - ENABLE/DISABLE PROCESSOR FUNCTIONS
	AH = C8h
	AL = function
	    00h disable L1 cache
	    01h enable L1 cache
	    ---models 90 and 95 only---
	    02h disable L2 cache
	    03h enable L2 cache
	    04h disable both caches
	    05h enable both caches
	    06h return status of both caches
	    07h-FFh Reserved
Return: CF set on error
	CF clear if successful
	AH = status (see #00527)
	For subfunction 06h only:
	    BL = status of L1 cache
		00h enabled
		01h disabled or not installed
		02h disabled due to test error (can not be enabled)
	    BH = status of L2 cache (same codes as BL)
Notes:	 supported by at least PS/2 70, 70/486, 80-A21, 90, 95
	call AH=C0h and examine bit 3 of feature byte 2 to check if this
	  function is supported.
	on a 486 system, any external caches must be disabled when the
	  on-chip cache (L1) is disabled.
SeeAlso: AH=C0h

(Table 00527)
Values for status:
 00h	operation successful
 01h	function choice (in AL) is invalid
 02h	NVRAM data is invalid
 03h	cache test error
 04h	(90 and 95 only) cannot perform operation requested due to state of
	  other cache (also see note above)
 05h	no L2 cache is present
 07h	invalid input values
 09h	CPU in protected mode

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15C9 - INT 15 - newer PS/2; various BIOSes - GET CPU TYPE AND MASK REVISION

INT 15 - newer PS/2; various BIOSes - GET CPU TYPE AND MASK REVISION
	AH = C9h
	AL = 10h (may be required on some non-PS BIOSes)
Return: CF clear if successful
	    AH = 00h
	    CH = CPU type (see #00528)
	    CL = mask revision (stepping level) (see #00529)
	CF set on error
	    AH = status (80h,86h = function not supported)
Notes:	the BIOS must save DX at startup in order to be able to support this
	  call; PS/2 Models 56, 57, 90, and 95 are known to support it
	the PS/2 BIOS merely reads CMOS locations 190h (type) and 191h (rev)
	IBM classifies this function as optional
SeeAlso: AX=D100h,AX=DA92h,MEM 0040h:00BCh

(Table 00528)
Values for CPU type:
 03h	80386DX or clone
 04h	80486
 05h	Pentium
 23h	80386SX or clone
 33h	Intel i376
 43h	80386SL or clone
 A3h	IBM 386SLC
 A4h	IBM 486SLC

(Table 00529)
Values for stepping level:
---i376 (type code 33h)---
 05h	A0
 08h	B
---80386/80386DX (type code 03h)---
 03h	Intel B1 to B10, Am386DX/DXL step A
 05h	Intel D0
 08h	Intel D1/D2/E1, Am386DX/DXL step B
---80386SL (type code 43h)---
 05h	A
 1xh	B
---80386SX (type code 23h)---
 04h	Intel A0
 05h	Intel B, Am386SX/SXL step A1
 08h	Intel C/D1, Am386SX/SXL step B
 09h	Intel 386CX/386EX/386SXstatic step A
---80486DX (type code 04h)---
 00h	Intel A0/A1
 01h	Intel B2 to B6
 02h	Intel C0
 03h	Intel C1
 04h	Intel D0
 10h	Intel cA2/cA3, Cx486SLC step A
 11h	Intel cB0/cB1
---486DX2 (type code 04h)---
 02h	Am486DX2 (unknown stepping)
 32h	Intel DX2/Overdrive steps A0 to A2
 33h	Intel DX2/Overdrive step B1
---486SX (type code 04h)---
 20h	Intel A0
 22h	Intel B0
 27h	Intel cA0
 28h	Intel cB0
---486SL (type code 04h)---
 40h	Intel A
---IntelSX2 (type code 04h)---
 5xh	Intel A
---IntelDX4 (type code 04h)---
 8xh	Intel A
---487SX (type code 04h)---
 20h	Intel A0
 21h	Intel B0
---Pentium (type code 05h)---
 0xh	Intel P5 steps Ax (1993)
 1xh	Intel P5 steps Bx (1994)
 2xh	Intel P54C step A
---RapidCAD (type code 03h)---
 40h	A

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15CA - INT 15 U - PS/2 Model 95 - READ/WRITE CMOS MEMORY

INT 15 U - PS/2 Model 95 - READ/WRITE CMOS MEMORY
	AH = CAh
	AL = function
	    00h read CMOS
		Return: CL = value of CMOS location
	    01h write CMOS
		CL = new value for CMOS location
	BL = CMOS location (0Eh-3Fh)
Return: CF clear if successful
	    AH = 00h
	CF set on error
	    AH = error code (see #00530)
Note:	writes do not update the CMOS checksum

(Table 00530)
Values for CMOS read/write error code:
 01h	CMOS lost power or has invalid checksum
 03h	specified location out of range (too high)
 04h	specified location out of range (too low)
 80h	unsupported function (PC)
 86h	unsupported function (XT)

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15CB - INT 15 U - PS/2 Model 95 - RESERVED

INT 15 U - PS/2 Model 95 - RESERVED
	AH = CBh
	???
Return: ???

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15CC - INT 15 U - PS/2 Model 95 - RESERVED

INT 15 U - PS/2 Model 95 - RESERVED
	AH = CCh
	???
Return: ???

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15CD - INT 15 U - PS/2 Model 95 - RESERVED

INT 15 U - PS/2 Model 95 - RESERVED
	AH = CDh
	???
Return: ???

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15CE--BL00 - INT 15 - later PS/2s - ALLOCATE DMA ARBITRATION LEVEL

INT 15 - later PS/2s - ALLOCATE DMA ARBITRATION LEVEL
	AH = CEh
	BL = 00h-0Eh arbitration level to be allocated
	     0Fh-FFh reserved
	AL = option byte
	    bit 7-1: reserved (0)
	    bit 0: 0 = need DMA channel for arbitration level requested
		   1 = no channel required for arbitration level
Return: CF set on error
	    AH = status (80h,86h = function not supported)
	CF clear on success
	    AL = channel number
		00h-07h channel number allocated for the arbiration level
		08h-FEh reserved
		FFh	no channel requested for arbitration level
	    AH = status (see #00531)
Notes:	 arbitration level 00h has the highest priority, 0Eh the lowest
	 to perform a DMA transfer operation, be sure to call this function
	   first, and call AH=CFh afterward.  Failure to use this function
	   can cause unpredictable results.
SeeAlso: AH=CFh

(Table 00531)
Values for DMA arbitration status:
 00h	success
 01h	arbitration level not available
 02h	channel not available
 03h	invalid arbitration level passed

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15CF - INT 15 - later PS/2s - DEALLOCATE DMA ARBITRATION LEVEL

INT 15 - later PS/2s - DEALLOCATE DMA ARBITRATION LEVEL
	AH = CFh
	BL = arbitration level to be deallocated (see AH=CEh)
Return: CF set on error
	    AH = status (80h,86h = function not supported)
	CF clear on success
	    AH = status
		00h success
		04h arbitration level not allocated
SeeAlso: AH=CEh

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15D0 - INT 15 - later PS/2s - RESERVED

INT 15 - later PS/2s - RESERVED
	AH = D0h
	???
Return: ???

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15D100DX0000 - INT 15 - later PS/2s - GET NUMBER OF DEVICE DESCRIPTOR TABLE (DDT) ENTRIES

INT 15 - later PS/2s - GET NUMBER OF DEVICE DESCRIPTOR TABLE (DDT) ENTRIES
	AX = D100h
	DX = 0000h (reserved, must set to 0)
Return: BL = size of one DDT entry, in bytes
	CX = number of DDT entries
	AH = return code (see #00534)
	CF set on error
	CF clear on success
SeeAlso: AH=C0h,AH=C7h,AH=C9h,AX=D101h,AX=D102h,AX=D103h,AX=D104h

(Table 00534)
Values for return code:
 00h	success
 01h	requested DDT entry not found
 02h	DDT data not valid
 86h	function not supported

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15D101 - INT 15 - later PS/2s - RETURN DEVICE DESCRIPTOR TABLE (DDT) ENTRY BY NUMBER

INT 15 - later PS/2s - RETURN DEVICE DESCRIPTOR TABLE (DDT) ENTRY BY NUMBER
	AX = D101h
	BX = number of requested entry (starting with 1)
	DX = 0000h (reserved, must be set to 0)
	ES:DI -> buffer to contain DDT entry (see #00535)
Return: AH = return code (see #00534)
	CF set on error
	CF clear on success
	    ES:DI buffer filled with DDT entry
SeeAlso: AH=C0h,AH=C7h,AH=C9h,AX=D100h,AX=D102h,AX=D104h

Format of Device Descriptor Table (DDT):
Offset	Size	Description	(Table 00535)
 00h	BYTE	bits 7-4: reserved (set to 0)
		bits 3-0: slot of device (0 = system board)
 01h	BYTE	bits 7-4: second interrupt for this device (0 = none)
		bits 3-0: first interrupt for this device (0 = none)
 02h	BYTE	bits 7-4: second arbitration level for this device
		bits 3-0: first arbitration level for this device
 03h	WORD	DDT indicators (see #00536)
 05h	BYTE	reserved (0)
 06h	WORD	device ID (0 = none)
 08h	WORD	starting address of first  I/O block (0 = none)
 0Ah	WORD	starting address of second I/O block (0 = none)
 OCh	WORD	starting address of third  I/O block (0 = none)
 OEh	DWORD	start of first non-system memory block (0 = none)
 12h	WORD	size of first non-system memory block (in kilobytes)
 14h	DWORD	start of second non-system memory block (0 = none)
 18h	WORD	size of second non-system memory block (in kilobytes)
 1Ah	BYTE	implementation identifier of the device
 1Bh	BYTE	implementation revision level of the device
Note:	I/O block addresses and non-system memory addresses are listed in
	  ascending order in each DDT entry.

Bitfields for DDT indicators:
Bit(s)	Description	(Table 00536)
 15	reserved (0)
 14	second arbitration level exists
 13	first arbitration level exists
 12	serial interface is RS-422
 11	not address limited
 10	DMA channel used
 9	second arbitration level can be shared
 8	first arbitration level can be shared
 7-0	reserved (0)

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15D102 - INT 15 - later PS/2s - RETURN DEVICE DESCRIPTOR TABLE (DDT) ENTRY BY I/O ADDRSS

INT 15 - later PS/2s - RETURN DEVICE DESCRIPTOR TABLE (DDT) ENTRY BY I/O ADDRSS
	AX = D102h
	BX = entry number at which to start searching
	CX = requested I/O port address
	DX = 0000h (reserved, must be set to 0)
	ES:DI -> buffer to contain DDT entry (see #00535)
Return: AH = return code (see #00534)
	BX = DDT entry number where I/O port was found, or total entries
	     plus 1 if port was not found.
	CF set on error
	CF clear on success
	    ES:DI buffer filled with DDT entry
Desc:	the DDT is searched from the specified entry for the I/O port in CX,
	  and the first entry in which it is found is returned
SeeAlso: AH=C0h,AH=C7h,AH=C9h,AX=D100h,AX=D101h,AX=D103h,AX=D104h

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15D103DX0000 - INT 15 - later PS/2s - RETURN ENTIRE DDT

INT 15 - later PS/2s - RETURN ENTIRE DDT
	AX = D103h
	DX = 0000h (reserved, must be set to 0)
	ES:DI -> buffer to contain DDT entry (see #00535)
Return: AH = return code (see #00534)
	CF set on error
	CF clear on success
	    ES:DI buffer filled with DDT entry
SeeAlso: AH=C0h,AH=C7h,AH=C9h,AX=D100h,AX=D104h

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15D104 - INT 15 - later PS/2s - RETURN DEVICE DESCRIPTOR TABLE (DDT) ENTRY BY DEVICE ID

INT 15 - later PS/2s - RETURN DEVICE DESCRIPTOR TABLE (DDT) ENTRY BY DEVICE ID
	AX = D104h
	BX = entry number at which to start searching
	CX = requested device ID
	DX = 0000h (reserved, must be set to 0)
	ES:DI -> buffer to contain DDT entry (see #00535)
Return: AH = return code (see #00534)
	BX = DDT entry number where device ID was found, or total entries
	      plus 1 if port was not found.
	CF set on error
	CF clear on success
	    ES:DI buffer filled with DDT entry
Desc:	the DDT is searched from the specified entry for the device ID in CX,
	  and the first entry in which it is found is returned.
SeeAlso: AH=C0h,AH=C7h,AH=C9h,AX=D100h,AX=D101h,AX=D103h

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15D2 - INT 15 - later PS/2s - RESERVED

INT 15 - later PS/2s - RESERVED
	AH = D2h
	???
Return: ???

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15D3 - INT 15 - later PS/2s - RESERVED

INT 15 - later PS/2s - RESERVED
	AH = D3h
	???
Return: ???

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15D4 - INT 15 - later PS/2s - GET PHYSICAL FIXED DISK DRIVE NUMBER (SELECTABLE BOOT)

INT 15 - later PS/2s - GET PHYSICAL FIXED DISK DRIVE NUMBER (SELECTABLE BOOT)
	AH = D4h
	DL = logical fixed disk drive number
Return: AH = return code (see #00537)
	CF set on error
	CF clear on success
	    AL = physical fixed disk drive number

(Table 00537)
Values for return code:
 00h	success
 01h	specified logical drive number is invalid
 80h	function not supported (on PCjr and PC)
 86h	function not supported

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15D5 - INT 15 - later PS/2s - RESERVED

INT 15 - later PS/2s - RESERVED
	AH = D5h
	???
Return: ???

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15D600BL00 - INT 15 - later PS/2s - READ BOOT DEVICE ID

INT 15 - later PS/2s - READ BOOT DEVICE ID
	AX = D600h
	BL = 00h
	DX = device ID
Return: CF clear if successful
	    AH = 00h
	CF set on error
	    AH = status (86h for function not supported)
SeeAlso: AX=D600h/BL=01h,AX=D601h/BL=00h,AX=D602h

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15D600BL01 - INT 15 - later PS/2s - WRITE BOOT DEVICE ID

INT 15 - later PS/2s - WRITE BOOT DEVICE ID
	AX = D600h
	BL = 01h
	DX = device ID
Return: CF clear on success
	    AH = 00h
	CF set on error
	    AH = status (86h for function not supported)
SeeAlso: AX=D600h/BL=00h,AX=D601h/BL=01h

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15D601BL00 - INT 15 - later PS/2s - READ BOOT DEVICE KEY

INT 15 - later PS/2s - READ BOOT DEVICE KEY
	AX = D601h
	BL = 00h
	DX = device ID
Return: CF clear on success
	    AH = 00h
	CF set on error
	    AH = status (86h for function not supported)
SeeAlso: AX=D600h/BL=00h,AX=D601h/BL=01h,AX=D602h

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15D601BL01 - INT 15 - later PS/2s - WRITE BOOT DEVICE KEY

INT 15 - later PS/2s - WRITE BOOT DEVICE KEY
	AX = D601h
	BL = 01h
	DX = device ID
Return: CF clear on success
	    AH = 00h
	CF set on error
	    AH = status (86h for function not supported)
SeeAlso: AX=D600h/BL=01h,AX=D601h/BL=00h

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15D602 - INT 15 - later PS/2s - QUERY BOOT REFERENCE PARTITION

INT 15 - later PS/2s - QUERY BOOT REFERENCE PARTITION
	AX = D602h
Return: CF clear on success
	    AH = 00h
	    AL = status of reference-partition boot request
		00h boot not requested
		01h boot requested
	CF set on error
	    AH = status (86h for function not supported)
SeeAlso: AX=D601h/BL=00h

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1600 - INT 16 - KEYBOARD - GET KEYSTROKE

INT 16 - KEYBOARD - GET KEYSTROKE
	AH = 00h
Return: AH = BIOS scan code
	AL = ASCII character
Notes:	on extended keyboards, this function discards any extended keystrokes,
	  returning only when a non-extended keystroke is available
	the BIOS scan code is usually, but not always, the same as the hardware
	  scan code processed by INT 09.  It is the same for ASCII keystrokes
	  and most unshifted special keys (F-keys, arrow keys, etc.), but
	  differs for shifted special keys
	some (older) clone BIOSes do not discard extended keystrokes and manage
	  function AH=00h and AH=10h the same
	the K3PLUS v6.00+ INT 16 BIOS replacement doesn't discard extended
	  keystrokes (same as with functions 10h and 20h), but will always
	  translate prefix E0h to 00h. This allows old programs to use extended
	  keystrokes and should not cause compatibility problems
SeeAlso: AH=01h,AH=05h,AH=10h,AH=20h,AX=AF4Dh"K3PLUS",INT 18/AH=00h
SeeAlso: INT 09,INT 15/AH=4Fh

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1601 - INT 16 - KEYBOARD - CHECK FOR KEYSTROKE

INT 16 - KEYBOARD - CHECK FOR KEYSTROKE
	AH = 01h
Return: ZF set if no keystroke available
	ZF clear if keystroke available
	    AH = BIOS scan code
	    AL = ASCII character
Note:	if a keystroke is present, it is not removed from the keyboard buffer;
	  however, any extended keystrokes which are not compatible with 83/84-
	  key keyboards are removed by IBM and most fully-compatible BIOSes in
	  the process of checking whether a non-extended keystroke is available
	some (older) clone BIOSes do not discard extended keystrokes and manage
	  function AH=00h and AH=10h the same
	the K3PLUS v6.00+ INT 16 BIOS replacement doesn't discard extended
	  keystrokes (same as with functions 10h and 20h), but will always
	  translate prefix E0h to 00h. This allows old programs to use extended
	  keystrokes and should not cause compatibility problems
SeeAlso: AH=00h,AH=11h,AH=21h,INT 18/AH=01h,INT 09,INT 15/AH=4Fh

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1602 - INT 16 - KEYBOARD - GET SHIFT FLAGS

INT 16 - KEYBOARD - GET SHIFT FLAGS
	AH = 02h
Return: AL = shift flags (see #00582)
	AH destroyed by many BIOSes
SeeAlso: AH=12h,AH=22h,INT 17/AH=0Dh,INT 18/AH=02h,MEM 0040h:0017h

Bitfields for keyboard shift flags:
Bit(s)	Description	(Table 00582)
 7	Insert active
 6	CapsLock active
 5	NumLock active
 4	ScrollLock active
 3	Alt key pressed (either Alt on 101/102-key keyboards)
 2	Ctrl key pressed (either Ctrl on 101/102-key keyboards)
 1	left shift key pressed
 0	right shift key pressed
SeeAlso: #00587,#03743,MEM 0040h:0017h,#M0010

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1603 - INT 16 - KEYBOARD - SET TYPEMATIC RATE AND DELAY

INT 16 - KEYBOARD - SET TYPEMATIC RATE AND DELAY
	AH = 03h
	AL = subfunction
	    00h set default delay and rate (PCjr and some PS/2)
	    01h increase delay before repeat (PCjr)
	    02h decrease repeat rate by factor of 2 (PCjr)
	    03h increase delay and decrease repeat rate (PCjr)
	    04h turn off typematic repeat (PCjr and some PS/2)
	    05h set repeat rate and delay (AT,PS)
		BH = delay value (00h = 250ms to 03h = 1000ms)
		BL = repeat rate (00h=30/sec to 0Ch=10/sec [def] to 1Fh=2/sec)
	    06h get current typematic rate and delay (newer PS/2s)
		Return: BL = repeat rate (above)
			BH = delay (above)
Return: AH destroyed by many BIOSes
Note:	use INT 16/AH=09h to determine whether some of the subfunctions are
	  supported
SeeAlso: INT 16/AH=09h,AH=29h"HUNTER",AH=2Ah"HUNTER"

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1604 - INT 16 - KEYBOARD - SET KEYCLICK (PCjr only)

INT 16 - KEYBOARD - SET KEYCLICK (PCjr only)
	AH = 04h
	AL = keyclick state
	    00h off
	    01h on
Return: AH destroyed by many BIOSes
SeeAlso: AH=03h,AH=04h"K3PLUS"

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1605 - INT 16 - KEYBOARD - STORE KEYSTROKE IN KEYBOARD BUFFER (AT/PS w enh keybd only)

INT 16 - KEYBOARD - STORE KEYSTROKE IN KEYBOARD BUFFER (AT/PS w enh keybd only)
	AH = 05h
	CH = BIOS scan code
	CL = ASCII character
Return: AL = status
	    00h if successful
	    01h if keyboard buffer full
	AH destroyed by many BIOSes
Notes:	under DESQview, a number of "keystrokes" invoke specific
	  DESQview-related actions when they are read from the keyboard
	  buffer (see #00583)
	similarly, some "keystrokes" invoke special functions on the HP 100LX
	  and HP 200LX (see #00584)
SeeAlso: AH=00h,AH=25h"K3",AH=71h,AX=AF4Dh,AH=FFh,INT 15/AX=DE10h
SeeAlso: MEM 0040h:001Eh

(Table 00583)
Values for pseudo-keystrokes for DESQview:
 38FBh or FB00h	switch to next window (only if main menu already popped up)
 38FCh or FC00h	pop up DESQview main menu
 38FEh or FE00h	close the current window
 38FFh or FF00h	pop up DESQview learn menu

(Table 00584)
Values for pseudo-keystrokes for HP 100LX/200LX:
 EE00h	pop up topcard display and set other system manager applications
	  into sleep mode

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1605 - INT 16 - KEYBOARD - SELECT KEYBOARD LAYOUT (PCjr only)

INT 16 - KEYBOARD - SELECT KEYBOARD LAYOUT (PCjr only)
	AH = 05h
	AL = function
	    01h set keyboard layout to French
	    02h set keyboard layout to German
	    03h set keyboard layout to Italian
	    04h set keyboard layout to Spanish
	    05h set keyboard layout to UK
	    80h check if function supported
		Return: AL <> 80h if supported
Return: ???
	AH destroyed by many BIOSes
Note:	this function is called by the DOS 3.2 KEYBxx.COM
SeeAlso: AH=92h,AH=A2h,AX=AF4Dh

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1609 - INT 16 - KEYBOARD - GET KEYBOARD FUNCTIONALITY

INT 16 - KEYBOARD - GET KEYBOARD FUNCTIONALITY
	AH = 09h
Return: AL = supported keyboard functions (see #00585)
	AH destroyed by many BIOSes
Note:	this function is only available if bit 6 of the second feature byte
	  returned by INT 15/AH=C0h is set (see #00509)
SeeAlso: AH=03h,AH=0Ah,AH=10h,AH=11h,AH=12h,AH=20h,AH=21h,AH=22h,INT 15/AH=C0h

Bitfields for supported keyboard functions:
Bit(s)	Description	(Table 00585)
 7	reserved
 6	INT 16/AH=20h-22h supported (122-key keyboard support)
 5	INT 16/AH=10h-12h supported (enhanced keyboard support)
 4	INT 16/AH=0Ah supported
 3	INT 16/AX=0306h supported
 2	INT 16/AX=0305h supported
 1	INT 16/AX=0304h supported
 0	INT 16/AX=0300h supported
SeeAlso: #00511

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1610 - INT 16 - KEYBOARD - GET ENHANCED KEYSTROKE (enhanced kbd support only)

INT 16 - KEYBOARD - GET ENHANCED KEYSTROKE (enhanced kbd support only)
	AH = 10h
Return: AH = BIOS scan code
	AL = ASCII character
Notes:	if no keystroke is available, this function waits until one is placed
	  in the keyboard buffer
	the BIOS scan code is usually, but not always, the same as the hardware
	  scan code processed by INT 09.  It is the same for ASCII keystrokes
	  and most unshifted special keys (F-keys, arrow keys, etc.), but
	  differs for shifted special keys.
	unlike AH=00h, this function does not discard extended keystrokes
	INT 16/AH=09h can be used to determine whether this function is
	  supported, but only on later model PS/2s
SeeAlso: AH=00h,AH=09h,AH=11h,AH=20h,MEM 0040h:0019h,MEM 0040h:001Eh

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1611 - INT 16 - KEYBOARD - CHECK FOR ENHANCED KEYSTROKE (enh kbd support only)

INT 16 - KEYBOARD - CHECK FOR ENHANCED KEYSTROKE (enh kbd support only)
	AH = 11h
Return: ZF set if no keystroke available
	ZF clear if keystroke available
	    AH = BIOS scan code
	    AL = ASCII character
Notes:	if a keystroke is available, it is not removed from the keyboard buffer
	unlike AH=01h, this function does not discard extended keystrokes
	some versions of the IBM BIOS Technical Reference erroneously report
	  that CF is returned instead of ZF
	INT 16/AH=09h can be used to determine whether this function is
	  supported, but only on later model PS/2s
SeeAlso: AH=01h,AH=09h,AH=10h,AH=21h,INT 09,INT 15/AH=4Fh

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1612 - INT 16 - KEYBOARD - GET EXTENDED SHIFT STATES (enh kbd support only)

INT 16 - KEYBOARD - GET EXTENDED SHIFT STATES (enh kbd support only)
	AH = 12h
Return: AL = shift flags 1 (same as returned by AH=02h) (see #00587)
	AH = shift flags 2 (see #00588)
Notes:	AL bit 3 set only for left Alt key on many machines
	AH bits 7 through 4 always clear on a Compaq SLT/286
	INT 16/AH=09h can be used to determine whether this function is
	  supported, but only on later model PS/2s
	many BIOSes (including at least some versions of Phoenix and AMI) will
	  destroy AH on return from functions higher than AH=12h, returning
	  12h less than was in AH on entry (due to a chain of DEC/JZ
	  instructions)
SeeAlso: AH=02h,AH=09h,AH=22h,AH=51h,INT 17/AH=0Dh,MEM 0040h:0017h

Bitfields for keyboard shift flags 1:
Bit(s)	Description	(Table 00587)
 7	Insert active
 6	CapsLock active
 5	NumLock active
 4	ScrollLock active
 3	Alt key pressed (either Alt on 101/102-key keyboards)
 2	Ctrl key pressed (either Ctrl on 101/102-key keyboards)
 1	left shift key pressed
 0	right shift key pressed
SeeAlso: #00582,#00588,MEM 0040h:0017h,#M0010

Bitfields for keyboard shift flags 2:
Bit(s)	Description	(Table 00588)
 7	SysReq key pressed (SysReq is often labeled SysRq)
 6	CapsLock pressed
 5	NumLock pressed
 4	ScrollLock pressed
 3	right Alt key pressed
 2	right Ctrl key pressed
 1	left Alt key pressed
 0	left Ctrl key pressed
SeeAlso: #00587,MEM 0040h:0018h,#M0011

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1620 - INT 16 - KEYBOARD - GET 122-KEY KEYSTROKE (122-key kbd support only)

INT 16 - KEYBOARD - GET 122-KEY KEYSTROKE (122-key kbd support only)
	AH = 20h
Return: AH = BIOS scan code (see AH=10h)
	AL = ASCII character
Note:	use AH=09h to determine whether this function is supported
SeeAlso: AH=00h,AH=09h,AH=10h,AH=21h,AH=22h

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1621 - INT 16 - KEYBOARD - CHECK FOR 122-KEY KEYSTROKE (122-key kbd support only)

INT 16 - KEYBOARD - CHECK FOR 122-KEY KEYSTROKE (122-key kbd support only)
	AH = 21h
Return: ZF set if no keystroke available
	ZF clear if keystroke available
	    AH = BIOS scan code
	    AL = ASCII character
Notes:	use AH=09h to determine whether this function is supported
	some versions of the IBM BIOS Technical Reference erroneously report
	  that CF is returned instead of ZF
	K3PLUS v6.00+ supports this function as an alias of AH=11h
SeeAlso: AH=01h,AH=09h,AH=11h,AH=20h,AH=21h

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1622 - INT 16 - KEYBOARD - GET 122-KEY SHIFT STATUS (122-key kbd support only)

INT 16 - KEYBOARD - GET 122-KEY SHIFT STATUS (122-key kbd support only)
	AH = 22h
Return: AL = shift flags 1 (see #00587)
	AH = shift flags 2 (see #00588)
Notes:	use AH=09h to determine whether this function is supported
	K3PLUS v6.00+ supports this function as an alias of AH=12h
SeeAlso: AH=02h,AH=09h,AH=12h,AH=20h,AH=21h

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1700 - INT 17 - PRINTER - WRITE CHARACTER

INT 17 - PRINTER - WRITE CHARACTER
	AH = 00h
	AL = character to write
	DX = printer number (00h-02h)
Return: AH = printer status (see #00631)
Note:	Under PhysTechSoft's PTS ROM-DOS the parallel port can also be
	  accessed as COM5.
BUGS:	Some print spoolers trash the BX register on return.
	Some original IBM BIOSes set more than one printer status bits at
	  a time, while only one of them is correct.
SeeAlso: AH=02h,AH=84h"AX",AX=6F02h,AH=F1h,INT 16/AX=FFE3h,INT 1A/AH=11h"NEC"
SeeAlso: INT 4B/AH=00h,PORT 0278h"PRINTER",MEM 0040h:0008h,MEM 0040h:0078h

Bitfields for printer status:
Bit(s)	Description	(Table 00631)
 7	not busy
 6	acknowledge
 5	out of paper
 4	selected
 3	I/O error
 2-1	unused
 0	timeout
Notes:	If both, bit 5 "out of paper" and 4 "selected" are set, the MS-DOS/
	  PC DOS kernel assumes that no printer is attached.
	for Tandy 2000, bit 7 indicates printer-busy when set rather than clear

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1701 - INT 17 - PRINTER - INITIALIZE PORT

INT 17 - PRINTER - INITIALIZE PORT
	AH = 01h
	DX = printer number (00h-02h)
Return: AH = printer status (see #00631)
Note:	some printers report that they are ready immediately after
	  initialization when they actually are not; a more reliable result may
	  be obtained by calling AH=02h after a brief delay
SeeAlso: AH=02h,AH=FFh"PC-MOS",INT 1A/AH=10h"NEC",INT 4B/AH=01h

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1702 - INT 17 - PRINTER - GET STATUS

INT 17 - PRINTER - GET STATUS
	AH = 02h
	DX = printer number (00h-02h)
Return: AH = printer status (see #00631)
Note:	PRINTFIX from MS-DOS 5.0 hooks this function and always returns AH=90h
SeeAlso: AH=01h,AH=F2h,INT 1A/AH=12h"NEC",INT 4B/AH=02h

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18 - INT 18 - DISKLESS BOOT HOOK (START CASSETTE BASIC)

INT 18 - DISKLESS BOOT HOOK (START CASSETTE BASIC)
Desc:	called when there is no bootable disk available to the system
Notes:	very few PCs other than those produced by IBM contain BASIC in ROM, so
	  the action is unpredictable on compatibles; this interrupt often
	  reboots the system, and often has no effect at all
	some PC and XT clones had an optional IBM CASSETTE BASIC stored
	  in the ROM, too.
	most BIOSes will display an error message similar to "NO BASIC", and
	  either reboot or return to the caller.
	PS/2 machines usually pop up a graphical box to the effect that
	  the user should enter a floppy and press F1.
	Some clones display the message "No boot device available,
	  strike F1 to retry, F2 for setup utility"
	network cards with their own BIOS can hook this interrupt to allow
	  a diskless boot off the network (even when a hard disk is present
	  if none of the partitions is marked as the boot partition)
SeeAlso: INT 2F/AX=4A06h,INT 86"NetBIOS",INT 2F/AX=4A06h,INT 2F/AX=4A07h

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19 - INT 19 - SYSTEM - BOOTSTRAP LOADER

INT 19 - SYSTEM - BOOTSTRAP LOADER
Desc:	This interrupt reboots the system without clearing memory or restoring
	  interrupt vectors.  Because interrupt vectors are preserved, this
	  interrupt usually causes a system hang if any TSRs have hooked
	  vectors from 00h through 1Ch, particularly INT 08.
Notes:	Usually, the BIOS will try to read sector 1, head 0, track 0 from drive
	  A: to 0000h:7C00h.  If this fails, and a hard disk is installed, the
	  BIOS will read sector 1, head 0, track 0 of the first hard disk.
	  This sector should contain a master bootstrap loader and a partition
	  table (see #00650).  After loading the master boot sector at
	  0000h:7C00h, the master bootstrap loader is given control
	  (see #00653).	It will scan the partition table for an active
	  partition, and will then load the operating system's bootstrap
	  loader (contained in the first sector of the active partition) and
	  give it control.
	true IBM PCs and most clones issue an INT 18 if neither floppy nor hard
	  disk have a valid boot sector
	to accomplish a warm boot equivalent to Ctrl-Alt-Del, store 1234h in
	  0040h:0072h and jump to FFFFh:0000h.	For a cold boot equivalent to
	  a reset, store 0000h at 0040h:0072h before jumping.
	VDISK.SYS hooks this interrupt to allow applications to find out how
	  much extended memory has been used by VDISKs (see #00649).  DOS 3.3+
	  PRINT hooks INT 19 but does not set up a correct VDISK header block
	  at the beginning of its INT 19 handler segment, thus causing some
	  programs to overwrite extended memory which is already in use.
	the default handler is at F000h:E6F2h for 100% compatible BIOSes
	MS-DOS 3.2+ hangs on booting (even from floppy) if the hard disk
	  contains extended partitions which point at each other in a loop,
	  since it will never find the end of the linked list of extended
	  partitions
	under Windows Real and Enhanced modes, calling INT 19 will hang the
	  system in the same was as under bare DOS; under Windows Standard
	  mode, INT 19 will successfully perform a cold reboot as it appears
	  to have been redirected to a MOV AL,0FEh/OUT 64h,AL sequence
BUG:	when loading the remainder of the DOS system files fails, various
	  versions of IBMBIO.COM/IO.SYS incorrectly restore INT 1E before
	  calling INT 19, assuming that the boot sector had stored the
	  contents of INT 1E at DS:SI instead of on the stack as it actually
	  does
SeeAlso: INT 14/AH=17h,INT 18"BOOT HOOK",INT 49"Tandy 2000",INT 5B"PC Cluster"
SeeAlso: MEM 0040h:0067h,MEM F000h:FFF0h,CMOS 0Fh

Format of VDISK header block (at beginning of INT 19 handler's segment):
Offset	Size	Description	(Table 00649)
 00h 18 BYTEs	n/a (for VDISK.SYS, the device driver header)
 12h 11 BYTEs	signature string "VDISK	 Vn.m" for VDISK.SYS version n.m
 1Dh 15 BYTEs	n/a
 2Ch  3 BYTEs	linear address of first byte of available extended memory

Format of hard disk master boot sector:
Offset	Size	Description	(Table 00650)
 00h 446 BYTEs	Master bootstrap loader code
1BEh 16 BYTEs	partition record for partition 1 (see #00651)
1CEh 16 BYTEs	partition record for partition 2
1DEh 16 BYTEs	partition record for partition 3
1EEh 16 BYTEs	partition record for partition 4
1FEh	WORD	signature, AA55h indicates valid boot block

Format of partition record:
Offset	Size	Description	(Table 00651)
 00h	BYTE	boot indicator (80h = active partition)
 01h	BYTE	partition start head
 02h	BYTE	partition start sector (bits 0-5)
 03h	BYTE	partition start track (bits 8,9 in bits 6,7 of sector)
 04h	BYTE	operating system indicator (see #00652)
 05h	BYTE	partition end head
 06h	BYTE	partition end sector (bits 0-5)
 07h	BYTE	partition end track (bits 8,9 in bits 6,7 of sector)
 08h	DWORD	sectors preceding partition
 0Ch	DWORD	length of partition in sectors
SeeAlso: #00650

(Table 00652)
Values for operating system indicator:
 00h	empty partition-table entry
 01h	DOS 12-bit FAT
 02h	XENIX root file system
 03h	XENIX /usr file system (obsolete)
 04h	DOS 16-bit FAT (up to 32M)
 05h	DOS 3.3+ extended partition
 06h	DOS 3.31+ Large File System (16-bit FAT, over 32M)
 07h	QNX
 07h	OS/2 HPFS
 07h	Windows NT NTFS
 07h	Advanced Unix
 07h	see partition boot record; could be any of the above or others
 08h	OS/2 (v1.0-1.3 only)
 08h	AIX bootable partition, SplitDrive
 08h	Commodore DOS
 08h	DELL partition spanning multiple drives
 09h	AIX data partition
 09h	Coherent filesystem
 0Ah	OS/2 Boot Manager
 0Ah	OPUS
 0Ah	Coherent swap partition
 0Bh	Windows95 with 32-bit FAT
 0Ch	Windows95 with 32-bit FAT (using LBA-mode INT 13 extensions)
 0Eh	logical-block-addressable VFAT (same as 06h but using LBA-mode INT 13)
 0Fh	logical-block-addressable VFAT (same as 05h but using LBA-mode INT 13)
 10h	OPUS
 11h	OS/2 Boot Manager hidden 12-bit FAT partition
 12h	Compaq Diagnostics partition
 14h	(resulted from using Novell DOS 7.0 FDISK to delete Linux Native part)
 14h	OS/2 Boot Manager hidden sub-32M 16-bit FAT partition
 16h	OS/2 Boot Manager hidden over-32M 16-bit FAT partition
 17h	OS/2 Boot Manager hidden HPFS partition
 17h	hidden NTFS partition
 18h	AST special Windows swap file ("Zero-Volt Suspend" partition)
 19h	Willowtech Photon coS
 1Bh	hidden Windows95 FAT32 partition
 1Ch	hidden Windows95 FAT32 partition (using LBA-mode INT 13 extensions)
 1Eh	hidden LBA VFAT partition
 20h	Willowsoft Overture File System (OFS1)
 21h	officially listed as reserved
 21h	FSo2
 23h	officially listed as reserved
 24h	NEC MS-DOS 3.x
 26h	officially listed as reserved
 31h	officially listed as reserved
 33h	officially listed as reserved
 34h	officially listed as reserved
 36h	officially listed as reserved
 38h	Theos
 3Ch	PowerQuest PartitionMagic recovery partition
 40h	VENIX 80286
 41h	Personal RISC Boot
 41h	PowerPC boot partition
 42h	SFS (Secure File System) by Peter Gutmann
 45h	EUMEL/Elan
 46h	EUMEL/Elan
 47h	EUMEL/Elan
 48h	EUMEL/Elan
 4Fh	Oberon boot/data partition
 50h	OnTrack Disk Manager, read-only partition
 51h	OnTrack Disk Manager, read/write partition
 51h	NOVELL
 52h	CP/M
 52h	Microport System V/386
 53h	OnTrack Disk Manager, write-only partition???
 54h	OnTrack Disk Manager (DDO)
 55h	EZ-Drive (see also INT 13/AH=FFh"EZ-Drive")
 56h	GoldenBow VFeature
 5Ch	Priam EDISK
 61h	SpeedStor
 63h	Unix SysV/386, 386/ix
 63h	Mach, MtXinu BSD 4.3 on Mach
 63h	GNU HURD
 64h	Novell NetWare 286
 64h	SpeedStore
 65h	Novell NetWare (3.11)
 67h	Novell
 68h	Novell
 69h	Novell
 70h	DiskSecure Multi-Boot
 71h	officially listed as reserved
 73h	officially listed as reserved
 74h	officially listed as reserved
 75h	PC/IX
 76h	officially listed as reserved
 7Eh	F.I.X.
 80h	Minix v1.1 - 1.4a
 81h	Minix v1.4b+
 81h	Linux
 81h	Mitac Advanced Disk Manager
 82h	Linux Swap partition
 82h	Prime
 82h	Solaris (Unix)
 83h	Linux native file system (ext2fs/xiafs)
 84h	OS/2-renumbered type 04h partition (related to hiding DOS C: drive)
 85h	Linux EXT
 86h	FAT16 volume/stripe set (Windows NT)
 87h	HPFS Fault-Tolerant mirrored partition
 87h	NTFS volume/stripe set
 93h	Amoeba file system
 94h	Amoeba bad block table
 98h	Datalight ROM-DOS SuperBoot
 99h	Mylex EISA SCSI
 A0h	Phoenix NoteBIOS Power Management "Save-to-Disk" partition
 A1h	officially listed as reserved
 A3h	officially listed as reserved
 A4h	officially listed as reserved
 A5h	FreeBSD, BSD/386
 A6h	OpenBSD
 A9h	NetBSD (http://www.netbsd.org/)
 B1h	officially listed as reserved
 B3h	officially listed as reserved
 B4h	officially listed as reserved
 B6h	officially listed as reserved
 B6h	Windows NT mirror set (master), FAT16 file system
 B7h	BSDI file system (secondarily swap)
 B7h	Windows NT mirror set (master), NTFS file system
 B8h	BSDI swap partition (secondarily file system)
 BEh	Solaris boot partition
 C0h	DR DOS/DR-DOS/Novell DOS secured partition
 C0h	CTOS
 C1h	DR DOS 6.0 LOGIN.EXE-secured 12-bit FAT partition
 C4h	DR DOS 6.0 LOGIN.EXE-secured 16-bit FAT partition
 C6h	DR DOS 6.0 LOGIN.EXE-secured Huge partition
 C6h	corrupted FAT16 volume/stripe set (Windows NT)
 C6h	Windows NT mirror set (slave), FAT16 file system
 C7h	Syrinx Boot
 C7h	corrupted NTFS volume/stripe set
 C7h	Windows NT mirror set (slave), NTFS file system
 CBh	Reserved for DR DOS/DR-DOS/OpenDOS secured FAT32
 CCh	Reserved for DR DOS/DR-DOS secured FAT32 (LBA)
 CEh	Reserved for DR DOS/DR-DOS secured FAT16 (LBA)
 D0h	Multiuser DOS secured FAT12
 D1h	Old Multiuser DOS secured FAT12
 D4h	Old Multiuser DOS secured FAT16 (<= 32M)
 D5h	Old Multiuser DOS secured extended partition
 D6h	Old Multiuser DOS secured FAT16 (> 32M)
 D8h	CP/M-86
 DBh	CP/M, Concurrent CP/M, Concurrent DOS
 DBh	CTOS (Convergent Technologies OS)
 E1h	SpeedStor 12-bit FAT extended partition
 E2h	DOS read-only (Florian Painke's XFDISK 1.0.4)
 E3h	DOS read-only
 E3h	Storage Dimensions
 E4h	SpeedStor 16-bit FAT extended partition
 E5h	officially listed as reserved
 E6h	officially listed as reserved
 EBh	BeOS BFS (BFS1)
 F1h	Storage Dimensions
 F2h	DOS 3.3+ secondary partition
 F3h	officially listed as reserved
 F4h	SpeedStor
 F4h	Storage Dimensions
 F5h	Prologue
 F6h	officially listed as reserved
 FEh	LANstep
 FEh	IBM PS/2 IML (Initial Microcode Load) partition
 FFh	Xenix bad block table
Note:	for partition type 07h, one should inspect the partition boot record
	  for the actual file system type
SeeAlso: #00651

(Table 00653)
Values Bootstrap loader is called with (IBM BIOS):
	CS:IP = 0000h:7C00h
	DH = access
	    bits 7-6,4-0: don't care
	    bit 5: =0 device supported by INT 13
	DL = boot drive
	    00h first floppy
	    80h first hard disk

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1A00 - INT 1A - TIME - GET SYSTEM TIME

INT 1A - TIME - GET SYSTEM TIME
	AH = 00h
Return: CX:DX = number of clock ticks since midnight
	AL = midnight flag, nonzero if midnight passed since time last read
Notes:	there are approximately 18.2 clock ticks per second, 1800B0h per 24 hrs
	  (except on Tandy 2000, where the clock runs at 20 ticks per second)
	IBM and many clone BIOSes set the flag for AL rather than incrementing
	  it, leading to loss of a day if two consecutive midnights pass
	  without a request for the time (e.g. if the system is on but idle)
	since the midnight flag is cleared, if an application calls this
	  function after midnight before DOS does, DOS will not receive the
	  midnight flag and will fail to advance the date
	Modern releases of MS-DOS/PC DOS (5.0+???) assume that AL is a day
	  rollover counter rather than a flag, as expected by older releases.
	  DOS 5 - 7.10 (Windows 98 SE) provide an undocumented CONFIG.SYS
	  SWITCHES=/T option to force the old behaviour of the day advancing
	  code, that is using a flag instead of a counter.
	DR DOS 3.31 - DR-DOS 7.03 handle AL as a flag.
SeeAlso: AH=01h,AH=02h,INT 21/AH=2Ch,INT 55"Tandy 2000",INT 4E/AH=02h"TI"
SeeAlso: INT 62/AX=0099h,MEM 0040h:006Ch,MEM 0040h:0070h

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1A01 - INT 1A - TIME - SET SYSTEM TIME

INT 1A - TIME - SET SYSTEM TIME
	AH = 01h
	CX:DX = number of clock ticks since midnight
Return: nothing
Notes:	there are approximately 18.2 clock ticks per second, 1800B0h per 24 hrs
	  (except on Tandy 2000, where the clock runs at 20 ticks per second)
	this call resets the midnight-passed flag
SeeAlso: AH=00h,AH=03h,INT 21/AH=2Dh

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1A02 - INT 1A - TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS)

INT 1A - TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS)
	AH = 02h
	CF clear to avoid bug (see below)
Return: CF clear if successful
	    CH = hour (BCD)
	    CL = minutes (BCD)
	    DH = seconds (BCD)
	    DL = daylight savings flag (00h standard time, 01h daylight time)
	CF set on error (i.e. clock not running or in middle of update)
Notes:	this function is also supported by the Sperry PC, which predates the
	  IBM AT; the data is returned in binary rather than BCD on the Sperry,
	  and DL is always 00h
	MS-DOS/PC DOS IO.SYS/IBMBIO.COM use this function to detect if a RTC
	  is preset by checking if the returned values are non-zero. If they
	  are, this function is called one more time, before it is assumed
	  that no RTC is present.
BUG:	some BIOSes leave CF unchanged if successful, so CF should be cleared
	  before calling this function
SeeAlso: AH=00h,AH=03h,AH=04h,INT 21/AH=2Ch

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1A03 - INT 1A - TIME - SET REAL-TIME CLOCK TIME (AT,XT286,PS)

INT 1A - TIME - SET REAL-TIME CLOCK TIME (AT,XT286,PS)
	AH = 03h
	CH = hour (BCD)
	CL = minutes (BCD)
	DH = seconds (BCD)
	DL = daylight savings flag (00h standard time, 01h daylight time)
Return: nothing
Note:	this function is also supported by the Sperry PC, which predates the
	  IBM AT; the data is specified in binary rather than BCD on the
	  Sperry, and the value of DL is ignored
SeeAlso: AH=01h,AH=03h,AH=05h,INT 21/AH=2Dh,INT 4B/AH=01h

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1A04 - INT 1A - TIME - GET REAL-TIME CLOCK DATE (AT,XT286,PS)

INT 1A - TIME - GET REAL-TIME CLOCK DATE (AT,XT286,PS)
	AH = 04h
	CF clear to avoid bug (see below)
Return: CF clear if successful
	    CH = century (BCD)
	    CL = year (BCD)
	    DH = month (BCD)
	    DL = day (BCD)
	CF set on error
Notes:	DR-DOS 7.02 (after 1998-06-06) and 7.03 hook this function and correct
	  the century to 20xx if the reported year is 1900..1980 to auto-fix
	  ROM-BIOSes which are not Year 2000 compliant. On a running system,
	  it would also correct the rollover bug from 1999/12/31 to 2000/01/01.
	  The latter can be turned off using the new CONFIG.SYS YEAR2000=ON|OFF
	  command, as hooking INT 1Ah can sometimes cause compatibility
	  problems with 3rd party software, e.g. NCR/Symbios/LSI Logic-based
	  SDMS PCI SCSI drivers (including all OEM drivers like from Asus,
	  Noma, etc.), some Flash-BIOS software like Asus PFLASH, Quarterdeck's
	  QEMM Stealth and Quick-Boot features.
	Using EXCLUDESTEALTHINT=1A, though, will allow QEMM's Stealth features
	  to coexist with the DR-DOS Year 2000 rollover support.
	Actually, the Y2K-fix is provided since OpenDOS 7.02 BETA 2+
	  (1997-08-13), but although these older releases corrected the
	  ROM-BIOS, they didn't pass all Y2K-test suites and had some obscure
	  and inexplicable PCI problems due to the fact that the original
	  INT 1Ah was called via indirect means.  Newer releases, however, use
	  a dynamically fixed-up direct jump to avoid these problems.
	PC DOS 7 plus Y2K fixes and PC DOS 2000 provide similar, though not
	  identical means, which cannot be switched off.
	MS-DOS and older issues of PC DOS do not provide any such means, and
	  thus requires extra Y2K-TSRs to be loaded when run on buggy BIOSes.
BUG:	some BIOSes, such as the 1998/07/25 system ROM in the Compaq Deskpro
	  EP/SB, leave CF unchanged if successful, so CF should be cleared
	  before calling this function
SeeAlso: AH=02h,AH=04h"Sperry",AH=05h,INT 21/AH=2Ah,INT 4B/AH=02h"TI"

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1A05 - INT 1A - TIME - SET REAL-TIME CLOCK DATE (AT,XT286,PS)

INT 1A - TIME - SET REAL-TIME CLOCK DATE (AT,XT286,PS)
	AH = 05h
	CH = century (BCD)
	CL = year (BCD)
	DH = month (BCD)
	DL = day (BCD)
Return: nothing
SeeAlso: AH=04h,INT 21/AH=2Bh"DATE",INT 4B/AH=00h"TI"

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1A06 - INT 1A - TIME - SET ALARM (AT,XT286,PS)

INT 1A - TIME - SET ALARM (AT,XT286,PS)
	AH = 06h
	CH = hour (BCD)
	CL = minutes (BCD)
	DH = seconds (BCD)
Return: CF set on error (alarm already set or clock stopped for update)
	CF clear if successful
Notes:	the alarm occurs every 24 hours until turned off, invoking INT 4A each
	  time
	the BIOS does not check for invalid values for the time, so the CMOS
	  clock chip's "don't care" setting (any values between C0h and FFh)
	  may be used for any or all three parts.  For example, to create an
	  alarm once a minute, every minute, call with CH=FFh, CL=FFh, and
	  DH=00h.
SeeAlso: AH=07h,AH=0Ch,INT 4A"SYSTEM"

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1A07 - INT 1A - TIME - CANCEL ALARM (AT,XT286,PS)

INT 1A - TIME - CANCEL ALARM (AT,XT286,PS)
	AH = 07h
Return: alarm disabled
Note:	does not disable the real-time clock's IRQ
SeeAlso: AH=06h,AH=0Dh,INT 70

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1A08 - INT 1A - TIME - SET RTC ACTIVATED POWER ON MODE (CONVERTIBLE)

INT 1A - TIME - SET RTC ACTIVATED POWER ON MODE (CONVERTIBLE)
	AH = 08h
	CH = hours in BCD
	CL = minutes in BCD
	DH = seconds in BCD
SeeAlso: AH=09h

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1A09 - INT 1A - TIME - READ RTC ALARM TIME AND STATUS (CONV,PS30)

INT 1A - TIME - READ RTC ALARM TIME AND STATUS (CONV,PS30)
	AH = 09h
Return: CH = hours in BCD
	CL = minutes in BCD
	DH = seconds in BCD
	DL = alarm status
	    00h alarm not enabled
	    01h alarm enabled but will not power up system
	    02h alarm will power up system
SeeAlso: AH=08h

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1A0A - INT 1A - TIME - READ SYSTEM-TIMER DAY COUNTER (XT2,PS)

INT 1A - TIME - READ SYSTEM-TIMER DAY COUNTER (XT2,PS)
	AH = 0Ah
Return: CF set on error
	CF clear if successful
	    CX = count of days since Jan 1,1980
SeeAlso: AH=04h,AH=0Bh

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1A0B - INT 1A - TIME - SET SYSTEM-TIMER DAY COUNTER (XT2,PS)

INT 1A - TIME - SET SYSTEM-TIMER DAY COUNTER (XT2,PS)
	AH = 0Bh
	CX = count of days since Jan 1,1980
Return: CF set on error
	CF clear if successful
SeeAlso: AH=05h,AH=0Ah

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1A0C - INT 1A - TIME - SET RTC DATE/TIME ACTIVATED POWER-ON MODE (IBM)

INT 1A - TIME - SET RTC DATE/TIME ACTIVATED POWER-ON MODE (IBM)
	AH = 0Ch
	CH = hours (BCD)
	CL = minutes (BCD)
	DH = seconds (BCD)
	DL = day of month (BCD)
Return: CF clear if successful
	CF set on error (alarm already set or clock nonfunctional)
Desc:	set an automatic power-on for a given time in the future
Note:	IBM classifies this function as optional
SeeAlso: AH=06h,AH=0Dh,AH=0Eh,INT 4A

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1A0D - INT 1A - TIME - RESET RTC DATE/TIME ACTIVATED POWER-ON MODE (IBM)

INT 1A - TIME - RESET RTC DATE/TIME ACTIVATED POWER-ON MODE (IBM)
	AH = 0Dh
Return: CF clear if successful
	CF set on error
Desc:	cancel a previously-set power-on alarm
Note:	IBM classifies this function as optional
SeeAlso: AH=07h,AH=0Ch,AH=0Eh

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1A0E - INT 1A - TIME - GET RTC DATE/TIME ALARM AND STATUS (IBM)

INT 1A - TIME - GET RTC DATE/TIME ALARM AND STATUS (IBM)
	AH = 0Eh
Return: CF clear if successful
	    BH = alarm status
		00h disabled
		01h enabled but will not power-up system
		02h enabled, system will power-up on activation
	    CH = alarm time, hours (BCD)
	    CL = alarm time, minutes (BCD)
	    DH = seconds (BCD)
	    DL = day of month (BCD)
	CF set on error
SeeAlso: AH=0Ch,AH=0Dh,AH=0Fh

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1A0F - INT 1A - TIME - INITIALIZE REAL-TIME CLOCK

INT 1A - TIME - INITIALIZE REAL-TIME CLOCK
	AH = 0Fh
	AL = reserved (0)
Return: CF clear if successful
	CF set on error
SeeAlso: AH=0Ch,AH=0Dh,AH=0Eh

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1B - INT 1B C - KEYBOARD - CONTROL-BREAK HANDLER

INT 1B C - KEYBOARD - CONTROL-BREAK HANDLER
Desc:	this interrupt is automatically called when INT 09 determines that
	  Control-Break has been pressed
Note:	normally points to a short routine in DOS which sets the Ctrl-C flag,
	  thus invoking INT 23h the next time DOS checks for Ctrl-C.
SeeAlso: INT 23,MEM 0040h:0071h

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1C - INT 1C - TIME - SYSTEM TIMER TICK

INT 1C - TIME - SYSTEM TIMER TICK
Desc:	this interrupt is automatically called on each clock tick by the INT 08
	  handler
Notes:	this is the preferred interrupt to chain when a program needs to be
	  invoked regularly
	not available on NEC 9800-series PCs
SeeAlso: INT 08,INT E2"PC Cluster"

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1D - INT 1D - SYSTEM DATA - VIDEO PARAMETER TABLES

INT 1D - SYSTEM DATA - VIDEO PARAMETER TABLES
Notes:	the default parameter table (see #01263) is located at F000h:F0A4h for
	  100% compatible BIOSes
	Under PhysTechSoft's PTS ROM-DOS this table is fictitious.
SeeAlso: INT 10/AH=00h

Format of video parameters:
Offset	Size	Description	(Table 01263)
 00h 16 BYTEs	6845 register values for modes 00h and 01h
 10h 16 BYTEs	6845 register values for modes 02h and 03h
 20h 16 BYTEs	6845 register values for modes 04h and 05h
 30h 16 BYTEs	6845 register values for modes 06h and 07h
 40h	WORD	bytes in video buffer for modes 00h and 01h (0800h)
 42h	WORD	bytes in video buffer for modes 02h and 03h (1000h)
 44h	WORD	bytes in video buffer for modes 04h and 05h (4000h)
 46h	WORD	bytes in video buffer for mode 06h (4000h)
 48h  8 BYTEs	columns on screen for each of modes 00h through 07h
 50h  8 BYTEs	CRT controller mode bytes for each of modes 00h through 07h
Note:	QEMM v7.5 Stealth appears to copy only the first 40h bytes of this
	  table into always-accessible memory

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1E - INT 1E - SYSTEM DATA - DISKETTE PARAMETERS

INT 1E - SYSTEM DATA - DISKETTE PARAMETERS
Notes:	the default parameter table (see #01264) is located at F000h:EFC7h for
	  100% compatible BIOSes
	if the table is changed, INT 13/AH=00h should be called to ensure that
	  the floppy-disk controller is appropriately reprogrammed
	before rebooting the machine, this pointer should be restored to point
	  to the original position of the floppy parameters in the ROM BIOS.
	  The DOS boot sector takes care of this and in the case of a bootstrap
	  error, resets the vector. It also passes the original pointer to the
	  IO.SYS/IBMDOS.COM file for possible later restoration.
	under PhysTechSoft's PTS ROM-DOS this table is fictitious.
	the DR-DOS multi-OS LOADER (at least 1.04 up to including DR-DOS 7.03)
	  does not alter the INT 1Eh vector when launching IBMBIO.COM files
	  via its boot methods "S" or "D".  Although this allows booting
	  (uncompressed) IBMBIO.COM files bigger than 29 KB, it may
	  occasionally cause the floppy parameters to get trashed due to a 
	  bug in the DR-DOS 7.03 IBMBIO.COM startup code.
BUG:	The 2nd level decompressor of the DR-DOS 7.03 IBMBIO.COM (1998/08/11 to
	  1999/07) start-up code erroneously assumes that the floppy parameters
	  reside at 0000h:7C00h (normally set up there by the boot sector)
	  instead of relying on the INT 1Eh vector to point at their location.
	  Since the "assumed" floppy parameters get moved around and INT 1Eh
	  gets updated to point to their new location, this may cause the
	  contents of the floppy params to get trashed, if they weren't
	  actually copied to 0000h:7C00h by the bootstrap loader (that is the
	  boot sector or the LOADER utility).
SeeAlso: INT 13/AH=0Fh,INT 41"HARD DISK 0",INT 4D/AH=0Ah

Format of diskette parameter table:
Offset	Size	Description	(Table 01264)
 00h	BYTE	first specify byte
		bits 7-4: step rate (Fh=2ms,Eh=4ms,Dh=6ms,etc.)
		bits 3-0: head unload time (0Fh = 240 ms)
 01h	BYTE	second specify byte
		bits 7-1: head load time (01h = 4 ms)
		bit    0: non-DMA mode (always 0)
		Note:	The DOS boot sector sets the head load time to 15ms,
			  however, one should retry the operation on failure
 02h	BYTE	delay until motor turned off (in clock ticks)
 03h	BYTE	bytes per sector (00h = 128, 01h = 256, 02h = 512, 03h = 1024)
 04h	BYTE	sectors per track (maximum if different for different tracks)
 05h	BYTE	length of gap between sectors (2Ah for 5.25", 1Bh for 3.5")
 06h	BYTE	data length (ignored if bytes-per-sector field nonzero)
 07h	BYTE	gap length when formatting (50h for 5.25", 6Ch for 3.5")
 08h	BYTE	format filler byte (default F6h)
 09h	BYTE	head settle time in milliseconds
 0Ah	BYTE	motor start time in 1/8 seconds
---IBM SurePath BIOS---
 0Bh	BYTE	maximum track number
 0Ch	BYTE	data transfer rate
 0Dh	BYTE	drive type in CMOS
SeeAlso: #03226 at INT 4D/AH=09h

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1F - INT 1F - SYSTEM DATA - 8x8 GRAPHICS FONT

INT 1F - SYSTEM DATA - 8x8 GRAPHICS FONT
Desc:	this vector points at 1024 bytes of graphics data, 8 bytes for each
	  character 80h-FFh
Notes:	graphics data for characters 00h-7Fh stored at F000h:FA6Eh in 100%
	  compatible BIOSes
	Under PhysTechSoft's PTS ROM-DOS this table is fictitious.
SeeAlso: INT 10/AX=5000h,INT 43

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40 - INT 40 - DISKETTE - ROM BIOS DISKETTE HANDLER RELOCATED BY HARD DISK BIOS

INT 40 - DISKETTE - ROM BIOS DISKETTE HANDLER RELOCATED BY HARD DISK BIOS
SeeAlso: INT 13/AH=00h,INT 13/AH=02h,INT 47"SuperBIOS",INT 63"Adaptec"

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41 - INT 41 - SYSTEM DATA - HARD DISK 0 PARAMETER TABLE ADDRESS [NOT A VECTOR!]

INT 41 - SYSTEM DATA - HARD DISK 0 PARAMETER TABLE ADDRESS [NOT A VECTOR!]
Notes:	the default parameter table array is located at F000h:E401h in 100%
	  compatible BIOSes; the pointer may be overridden by the hard disk
	  controller's BIOS to support drive formats unknown to the ROM BIOS
	not used by some PS/2 models
	BIOSes which support four hard drives may store the parameter tables
	  for drives 81h-83h immediately following the parameter table pointed
	  at by INT 41, with a separate copy of the drive 81h table for INT 46.
	  The check for such an arrangement is to test whether INT 46 points
	  somewhere other than exactly 16 bytes past INT 41, and the sixteen
	  bytes starting at offset 10h from INT 41 are identical to the sixteen
	  bytes pointed at by INT 46
	another arrangement for BIOSes which support four IDE drives is to have
	  four tables pointed at by INT 41 in the order primary master,
	  primary slave, secondary master, and secondary slave, in which case
	  (for example) a system with only primary master and secondary master
	  will have valid tables at offsets 00h and 20h, with garbage (but
	  sectors-per-track = 00h) at offsets 10h and 30h
SeeAlso: #03196,INT 13/AH=09h,INT 1E,INT 46"HARD DISK 1",INT 60"Adaptec"
SeeAlso: INT C0"AMI"

Format of fixed disk parameters:
Offset	Size	Description	(Table 03196)
 00h	WORD	number of cylinders
 02h	BYTE	number of heads
 03h	WORD	starting reduced write current cylinder (XT only, 0 for others)
 05h	WORD	starting write precompensation cylinder number
 07h	BYTE	maximum ECC burst length (XT only)
 08h	BYTE	control byte (see #03197,#03198)
 09h	BYTE	standard timeout (XT only, 0 for others)
 0Ah	BYTE	formatting timeout (XT and WD1002 only, 0 for others)
 0Bh	BYTE	timeout for checking drive (XT and WD1002 only, 0 for others)
 0Ch	WORD	cylinder number of landing zone (AT and later only)
 0Eh	BYTE	number of sectors per track (AT and later only)
 0Fh	BYTE	reserved
SeeAlso: #00273,#00277

Bitfields for XT fixed disk control byte:
Bit(s)	Description	(Table 03197)
 2-0	drive step speed
	000  3ms
	100  200ms
	101  70ms (default)
	110  3ms
	111  3ms
 5-3	unused
 6	disable ECC retries
 7	disable access retries

Bitfields for AT fixed disk control byte:
Bit(s)	Description	(Table 03198)
 0	unused
 1	reserved (0)  (disable IRQ)
 2	reserved (0)  (no reset)
 3	set if more than 8 heads
 4	always 0
 5	set if manufacturer's defect map on max cylinder+1  (AT and later only)
 6	disable ECC retries
 7	disable access retries

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46 - INT 46 - SYSTEM DATA - HARD DISK 1 DRIVE PARAMETER TABLE ADDRESS [NOT A VECTOR!]

INT 46 - SYSTEM DATA - HARD DISK 1 DRIVE PARAMETER TABLE ADDRESS [NOT A VECTOR!]
Note:	not used by some PS/2 models
SeeAlso: INT 13/AH=09h,INT 41"HARD DISK 0",INT 60"Adaptec",INT C0"AMI"

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48 - INT 48 - KEYBOARD - CORDLESS KEYBOARD TRANSLATION (PCjr)

INT 48 - KEYBOARD - CORDLESS KEYBOARD TRANSLATION (PCjr)
	AL = scan code???
Note:	This interrupt may be un-initialized (0000h:0000h) on old machines.
	  This should be checked before calling or hooking this vector.
	MS-DOS/PC DOS 3.3x-4.x KEYB hooked the INT 48h handler. For AL <= 80h
	  it checked that either ALT and neither CTRL key was pressed,
	  and in that case, it cleared the CTRL flag in the BIOS variable at
	  0040:0017h and stored its contents in an internal variable,
	  before continuing with the previous (non-zero) INT 48h handler.
SeeAlso: INT 49"PCjr"

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49 - INT 49 - SYSTEM DATA - NON-KEYBOARD SCAN-CODE TRANSLATION TABLE (PCjr)

INT 49 - SYSTEM DATA - NON-KEYBOARD SCAN-CODE TRANSLATION TABLE (PCjr)
SeeAlso: #03208,INT 48"PCjr"

Format of PCjr scan-code translation table:
Offset	Size	Description	(Table 03208)
 00h	BYTE	number of non-keyboard scancodes in the table
 01h  N WORDs	high byte 00h (NUL) byte scancode with low order byte
		  representing the scancode mapped values relative to their
		  input values within the range of 56h through 7Eh

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4A - INT 4A C - SYSTEM - USER ALARM HANDLER

INT 4A C - SYSTEM - USER ALARM HANDLER
Desc:	This interrupt is invoked by the BIOS when a real-time clock alarm
	  occurs; an application may use it to perform an action at a
	  predetermined time.
Note:	this interrupt is called from within a hardware interrupt handler,
	  so all usual precautions against reentering DOS must be taken
SeeAlso: INT 1A/AH=06h

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4D00 - INT 4D - TI Professional PC - DISK - RESET DISK SYSTEM

INT 4D - TI Professional PC - DISK - RESET DISK SYSTEM
	AH = 00h
	DL = drive (if bit 7 is set both hard disks and floppy disks reset)
Return: AH = status (see #00234 at INT 13/AH=01h)
	CF clear if successful (returned AH=00h)
	CF set on error
Note:	this function is the same as INT 13/AH=00h on a standard PC BIOS
SeeAlso: AH=01h,AH=02h,AH=08h,AH=0Bh,INT 13/AH=00h,INT 46"TI Professional"
SeeAlso: INT 48/AH=00h"TI Professional",INT 4A/AH=00h"TI"

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4D01 - INT 4D - TI Professional PC - DISK - GET STATUS OF LAST OPERATION

INT 4D - TI Professional PC - DISK - GET STATUS OF LAST OPERATION
	AH = 01h
	DL = drive (bit 7 set for hard disk)
Return: CF clear if status unchanged
	CF set if status changed since last call
	AH = 00h
	AL = status of previous operation (see #00234 at INT 13/AH=01h)
Notes:	this function is nearly the same as INT 13/AH=01h on a standard PC BIOS
	the TI's BIOS tranparently performs a number of retries, and an error
	  status is only reported if all of the retries fail.  To get the error
	  status if the operation succeeded on a retry, use AH=07h instead
SeeAlso: AH=00h,AH=07h,INT 13/AH=01h

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4D02 - INT 4D - TI Professional PC - DISK - READ SECTOR(S) INTO MEMORY

INT 4D - TI Professional PC - DISK - READ SECTOR(S) INTO MEMORY
	AH = 02h
	AL = number of sectors to read (must be nonzero)
	CH = low eight bits of cylinder number
	CL = sector number 1-63 (bits 0-5)
	     high two bits of cylinder (bits 6-7, hard disk only)
	DH = head number
	DL = drive number (bit 7 set for hard disk)
	ES:BX -> data buffer
Return: CF set on error
	    if AH = 11h (corrected ECC error), AL = burst length
	CF clear if successful
	AH = status (see #00234 at INT 13/AH=01h)
	AL = number of sectors transferred
	ES:BX -> buffer for last sector processed (including one with errors)
SeeAlso: AH=00h,AH=01h,AH=03h,AH=04h,INT 13/AH=02h

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4D03 - INT 4D - TI Professional PC - DISK - WRITE SECTOR(S) FROM MEMORY

INT 4D - TI Professional PC - DISK - WRITE SECTOR(S) FROM MEMORY
	AH = 03h
	AL = number of sectors to write (must be nonzero)
	CH = low eight bits of cylinder number
	CL = sector number 1-63 (bits 0-5)
	     high two bits of cylinder (bits 6-7, hard disk only)
	DH = head number
	DL = drive number (bit 7 set for hard disk)
	ES:BX -> buffer containing data
Return: CF set on error
	    if AH = 11h (corrected ECC error), AL = burst length
	CF clear if successful
	AH = status (see #00234 at INT 13/AH=01h)
	AL = number of sectors transferred
	ES:BX -> buffer for last sector processed (including one with errors)
SeeAlso: AH=00h,AH=01h,AH=02h,AH=04h,INT 13/AH=03h

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4D04 - INT 4D - TI Professional PC - DISK - VERIFY DISK SECTOR CRC(S)

INT 4D - TI Professional PC - DISK - VERIFY DISK SECTOR CRC(S)
	AH = 04h
	AL = number of sectors to verify (must be nonzero)
	CH = low eight bits of cylinder number
	CL = sector number 1-63 (bits 0-5)
	     high two bits of cylinder (bits 6-7, hard disk only)
	DH = head number
	DL = drive number (bit 7 set for hard disk)
	ES:BX -> data buffer
Return: CF set on error
	    if AH = 11h (corrected ECC error), AL = burst length
	CF clear if successful
	AH = status (see #00234 at INT 13/AH=01h)
	AL = number of sectors transferred
	ES:BX -> buffer for last sector processed (including one with errors)
Note:	even though no data is transferred, ES:BX must still be valid
SeeAlso: AH=00h,AH=01h,AH=02h,AH=06h,INT 13/AH=04h

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4D05 - INT 4D - TI Professional PC - DISK - NOP

INT 4D - TI Professional PC - DISK - NOP
	AH = 05h
Note:	on the TI Pro, FORMAT.COM contains direct port I/O commands to perform
	  disk formatting, rather than using the BIOS

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4D06 - INT 4D - TI Professional PC - DISK - VERIFY DISK SECTOR(S)

INT 4D - TI Professional PC - DISK - VERIFY DISK SECTOR(S)
	AH = 06h
	AL = number of sectors to verify (must be nonzero)
	CH = low eight bits of cylinder number
	CL = sector number 1-63 (bits 0-5)
	     high two bits of cylinder (bits 6-7, hard disk only)
	DH = head number
	DL = drive number (bit 7 set for hard disk)
	ES:BX -> data buffer
Return: CF set on error
	    if AH = 11h (corrected ECC error), AL = burst length
	CF clear if successful
	AH = status (see #00234 at INT 13/AH=01h)
	AL = number of sectors transferred
	ES:BX -> buffer for last sector processed (including one with errors)
Note:	even though no data is transferred, ES:BX must still be valid because
	  an actual comparison with disk data is performed, not just the CRC
	  check of the standard PC BIOS or INT 4D/AH=04h
SeeAlso: AH=00h,AH=01h,AH=02h,AH=04h,INT 13/AH=04h

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4D07 - INT 4D - TI Professional PC - DISK - GET RETRY STATUS OF LAST OPERATION

INT 4D - TI Professional PC - DISK - GET RETRY STATUS OF LAST OPERATION
	AH = 07h
	DL = drive (bit 7 set for hard disk)
Return: CF clear if status unchanged
	CF set if status changed since last call
	AH = 00h
	AL = status of previous operation (see #00234 at INT 13/AH=01h)
Notes:	this function is nearly the same as INT 13/AH=01h on a standard PC BIOS
	the TI's BIOS tranparently performs a number of retries; this function
	  returns the error status of a failed operation even if the operation
	  succeeded on a retry
SeeAlso: AH=00h,AH=01h,INT 13/AH=01h

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4D08 - INT 4D - TI Professional PC - DISK - SET STANDARD DEVICE INTERFACE TABLE

INT 4D - TI Professional PC - DISK - SET STANDARD DEVICE INTERFACE TABLE
	AH = 08h
	DL = drive number (00h-03h)
	AL = drive type
	    00h single-sided 48 tpi (40-track, 8 sectors, 512 bytes/sector)
	    01h double-sided 48 tpi (40-track, 8 sectors, 512 bytes/sector)
	    02h single-sided 96 tpi (80-track, 8 sectors, 512 bytes/sector)
	    03h double-sided 96 tpi (80-track, 8 sectors, 512 bytes/sector)
Return: nothing???
SeeAlso: AH=00h,AH=09h

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4D09 - INT 4D - TI Professional PC - DISK - SET DEVICE INTERFACE TABLE ADDRESS

INT 4D - TI Professional PC - DISK - SET DEVICE INTERFACE TABLE ADDRESS
	AH = 09h
	DL = drive number (00h-07h)
	ES:BX -> Device Interface Table (see #03226)
Return: nothing???
SeeAlso: AH=00h,AH=08h,AH=0Ah,INT 1E

Format of TI Professional PC Device Interface Table:
Offset	Size	Description	(Table 03226)
 00h	DWORD	-> entry point for disk routine
 04h	WORD	bytes per sector
 06h	BYTE	sectors per track
 07h	BYTE	number of heads
 08h	BYTE	number of cylinders
 09h	BYTE	retry count
 0Ah	BYTE	precompensation start
SeeAlso: #01264 at INT 1E

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4D0A - INT 4D - TI Professional PC - DISK - GET DEVICE INTERFACE TABLE ADDRESS

INT 4D - TI Professional PC - DISK - GET DEVICE INTERFACE TABLE ADDRESS
	AH = 0Ah
	DL = drive number (00h-07h)
Return: AH = status
	ES:BX -> Device Interface Table (see #03226)
SeeAlso: AH=00h,AH=08h,AH=09h,INT 1E

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4D0B - INT 4D - TI Professional PC - DISK - TURN OFF ALL DRIVES

INT 4D - TI Professional PC - DISK - TURN OFF ALL DRIVES
	AH = 0Bh
Return: AH = 00h
Note:	used for diagnostics or to conserve power
SeeAlso: AH=00h

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FE - INT FE - AT/XT286/PS50+ - destroyed by return from protected mode

INT FE - AT/XT286/PS50+ - destroyed by return from protected mode
Note:	the ROM BIOS uses 0030h:0100h as the initial stack on startup, which
	  is the last fourth of the interrupt vector table.  If the processor
	  is returned to real mode via a hardware reset (the only possibility
	  on an 80286, though there are a number of ways of generating one),
	  then the BIOS startup code stacks three words on its scratch stack
	  before determining that a return to real mode has been requested.
	  As a result, INT FE and INT FF are corrupted.
SeeAlso: INT FF"XT286"

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FF - INT FF - AT/XT286/PS50+ - destroyed by return from protected mode

INT FF - AT/XT286/PS50+ - destroyed by return from protected mode
Note:	(see INT FE"XT286")
SeeAlso: INT FE"XT286"

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