Index for interrupt INT 19

Table of Contents by Order
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