A.1 BIOS Interrupt Overview

This list is a brief description of each of the 256 interrupts. Each
description begins with "INT nn " where "nn" is a two digit hexadecimal
number 00 - FF. For automatic processing, do not rely on the order being
consecutive.

--------!---TITLES---------------------------
INT 00 - CPU-generated - DIVIDE ERROR
INT 01 - CPU-generated - SINGLE STEP; (80386+) - DEBUGGING EXCEPTIONS
INT 02 - external hardware - NON-MASKABLE INTERRUPT
INT 03 - CPU-generated - BREAKPOINT
INT 04 - CPU-generated - INTO DETECTED OVERFLOW
INT 05 - PRINT SCREEN; CPU-generated (80186+) - BOUND RANGE EXCEEDED
INT 06 - CPU-generated (80286+) - INVALID OPCODE
INT 07 - CPU-generated (80286+) - PROCESSOR EXTENSION NOT AVAILABLE
INT 08 - IRQ0 - SYSTEM TIMER; CPU-generated (80286+)
INT 09 - IRQ1 - KEYBOARD DATA READY; CPU-generated (80286,80386)
INT 0A - IRQ2 - LPT2/EGA,VGA/IRQ9; CPU-generated (80286+)
INT 0B - IRQ3 - SERIAL COMMUNICATIONS (COM2); CPU-generated (80286+)
INT 0C - IRQ4 - SERIAL COMMUNICATIONS (COM1); CPU-generated (80286+)
INT 0D - IRQ5 - FIXED DISK/LPT2/reserved; CPU-generated (80286+)
INT 0E - IRQ6 - DISKETTE CONTROLLER; CPU-generated (80386+)
INT 0F - IRQ7 - PARALLEL PRINTER
INT 10 - VIDEO; CPU-generated (80286+)
INT 11 - BIOS - GET EQUIPMENT LIST; CPU-generated (80486+)
INT 12 - BIOS - GET MEMORY SIZE
INT 13 - DISK
INT 14 - SERIAL
INT 15 - CASSETTE
INT 16 - KEYBOARD
INT 17 - PRINTER
INT 18 - DISKLESS BOOT HOOK (START CASSETTE BASIC)
INT 19 - SYSTEM - BOOTSTRAP LOADER
INT 1A - TIME
INT 1B - KEYBOARD - CONTROL-BREAK HANDLER
INT 1C - TIME - SYSTEM TIMER TICK
INT 1D - SYSTEM DATA - VIDEO PARAMETER TABLES
INT 1E - SYSTEM DATA - DISKETTE PARAMETERS
INT 1F - SYSTEM DATA - 8x8 GRAPHICS FONT
INT 20 - DOS 1+ - TERMINATE PROGRAM
INT 21 - DOS 1+ - Function Calls
INT 22 - DOS 1+ - PROGRAM TERMINATION ADDRESS
INT 23 - DOS 1+ - CONTROL-C/CONTROL-BREAK HANDLER
INT 24 - DOS 1+ - CRITICAL ERROR HANDLER
INT 25 - DOS 1+ - ABSOLUTE DISK READ
INT 26 - DOS 1+ - ABSOLUTE DISK WRITE
INT 27 - DOS 1+ - TERMINATE AND STAY RESIDENT
INT 28 - DOS 2+ - DOS IDLE INTERRUPT
INT 29 - DOS 2+ - FAST CONSOLE OUTPUT
INT 2A - NETBIOS
INT 2B - DOS 2+ - RESERVED
INT 2C - DOS 2+ - RESERVED
INT 2D - DOS 2+ - RESERVED
INT 2E - DOS 2+ - PASS COMMAND TO COMMAND INTERPRETER FOR EXECUTION
INT 2F - Multiplex
INT 30 - (NOT A VECTOR!) - DOS 1+ - FAR JMP instruction
INT 31 - overwritten by CP/M jump instruction in INT 30
INT 32 - (no special use)
INT 33 - MS MOUSE
INT 34 - FLOATING POINT EMULATION - OPCODE D8h
INT 35 - FLOATING POINT EMULATION - OPCODE D9h
INT 36 - FLOATING POINT EMULATION - OPCODE DAh
INT 37 - FLOATING POINT EMULATION - OPCODE DBh
INT 38 - FLOATING POINT EMULATION - OPCODE DCh
INT 39 - FLOATING POINT EMULATION - OPCODE DDh
INT 3A - FLOATING POINT EMULATION - OPCODE DEh
INT 3B - FLOATING POINT EMULATION - OPCODE DFh
INT 3C - FLOATING POINT EMULATION - SEGMENT OVERRIDE
INT 3D - FLOATING POINT EMULATION - STANDALONE FWAIT
INT 3E - FLOATING POINT EMULATION - Borland "SHORTCUT" CALL
INT 3F - Overlay manager interrupt (Microsoft/Borland)
INT 40 - DISKETTE - RELOCATED ROM BIOS DISKETTE HANDLER
INT 41 - SYSTEM DATA - HARD DISK 0 PARAMETER TABLE; CPU - MS Windows
INT 42 - VIDEO - RELOCATED DEFAULT INT 10 VIDEO SERVICES (EGA,VGA)
INT 43 - VIDEO DATA - CHARACTER TABLE (EGA,MCGA,VGA)
INT 44 - VIDEO DATA - CHARACTER FONT (PCjr); Novell NetWare
INT 45 - Z100/Acorn
INT 46 - SYSTEM DATA - HARD DISK 1 DRIVE PARAMETER TABLE
INT 47 - Z100/Acorn/Western Digital/SQL Base
INT 48 - KEYBOARD (PCjr) - Z100/Watstar/Acorn/Western Digital/Compaq
INT 49 - SYSTEM DATA (PCjr) - Z100/TI/Watstar/Acorn/MAGic
INT 4A - SYSTEM - USER ALARM HANDLER
INT 4B - IBM SCSI interface; Virtual DMA Specification (VDS)
INT 4C - Z100/Acorn/TI
INT 4D - Z100
INT 4E - TI/Z100
INT 4F - Common Access Method SCSI
INT 50 - IRQ0 relocated by software
INT 51 - IRQ1 relocated by software
INT 52 - IRQ2 relocated by software
INT 53 - IRQ3 relocated by software
INT 54 - IRQ4 relocated by software
INT 55 - IRQ5 relocated by software
INT 56 - IRQ6 relocated by software
INT 57 - IRQ7 relocated by software
INT 58 - IRQ8/0 relocated by software
INT 59 - IRQ9/1 relocated by software; GSS Computer Graphics Interface
INT 5A - IRQ10/2 relocated by software
INT 5B - IRQ11/3 relocated by software; Network
INT 5C - IRQ12/4 relocated by software; Network Interface
INT 5D - IRQ13/5 relocated by software
INT 5E - IRQ14/6 relocated by software
INT 5F - IRQ15/7 relocated by software; HP 95LX GRAPHICS PRIMITIVES
INT 60 - reserved for user interrupt; multiple purposes
INT 61 - reserved for user interrupt; multiple purposes
INT 62 - reserved for user interrupt; multiple purposes
INT 63 - reserved for user interrupt; multiple purposes
INT 64 - reserved for user interrupt; multiple purposes
INT 65 - reserved for user interrupt; multiple purposes
INT 66 - reserved for user interrupt; multiple purposes
INT 67 - reserved for user interrupt; LIM EMS; multiple purposes
INT 68 - multiple purposes
INT 69 - multiple purposes
INT 6A - multiple purposes
INT 6B - multiple purposes
INT 6C - CONVERTIBLE; DOS 3.2; DECnet DOS network scheduler
INT 6D - VGA - internal
INT 6E - DECnet DOS - DECnet NETWORK PROCESS API
INT 6F - Novell NetWare; 10NET; MS Windows 3.0
INT 70 - IRQ8 - CMOS REAL-TIME CLOCK
INT 71 - IRQ9 - REDIRECTED TO INT 0A BY BIOS
INT 72 - IRQ10 - RESERVED
INT 73 - IRQ11 - RESERVED
INT 74 - IRQ12 - POINTING DEVICE (PS)
INT 75 - IRQ13 - MATH COPROCESSOR EXCEPTION (AT and up)
INT 76 - IRQ14 - HARD DISK CONTROLLER (AT and later)
INT 77 - IRQ15 - RESERVED (AT,PS); POWER CONSERVATION (Compaq)
INT 78 - DOS extenders; multiple purposes
INT 79 - multiple purposes
INT 7A - Novell NetWare; IBM 3270; multiple purposes
INT 7B - multiple purposes
INT 7C - multiple purposes
INT 7D - multiple purposes
INT 7E - RESERVED FOR DIP, Ltd. ROM LIBRARY; multiple purposes
INT 7F - multiple purposes
INT 80 - reserved for BASIC; multiple purposes
INT 81 - reserved for BASIC
INT 82 - reserved for BASIC
INT 83 - reserved for BASIC
INT 84 - reserved for BASIC
INT 85 - reserved for BASIC
INT 86 - IBM ROM BASIC - used while in interpreter; multiple purposes
INT 87 - IBM ROM BASIC - used while in interpreter
INT 88 - IBM ROM BASIC - used while in interpreter; multiple purposes
INT 89 - IBM ROM BASIC - used while in interpreter
INT 8A - IBM ROM BASIC - used while in interpreter
INT 8B - IBM ROM BASIC - used while in interpreter
INT 8C - IBM ROM BASIC - used while in interpreter
INT 8D - IBM ROM BASIC - used while in interpreter
INT 8E - IBM ROM BASIC - used while in interpreter
INT 8F - IBM ROM BASIC - used while in interpreter
INT 90 - IBM ROM BASIC - used while in interpreter
INT 91 - IBM ROM BASIC - used while in interpreter
INT 92 - IBM ROM BASIC - used while in interpreter; multiple purposes
INT 93 - IBM ROM BASIC - used while in interpreter
INT 94 - IBM ROM BASIC - used while in interpreter; multiple purposes
INT 95 - IBM ROM BASIC - used while in interpreter
INT 96 - IBM ROM BASIC - used while in interpreter
INT 97 - IBM ROM BASIC - used while in interpreter
INT 98 - IBM ROM BASIC - used while in interpreter
INT 99 - IBM ROM BASIC - used while in interpreter
INT 9A - IBM ROM BASIC - used while in interpreter
INT 9B - IBM ROM BASIC - used while in interpreter
INT 9C - IBM ROM BASIC - used while in interpreter
INT 9D - IBM ROM BASIC - used while in interpreter
INT 9E - IBM ROM BASIC - used while in interpreter
INT 9F - IBM ROM BASIC - used while in interpreter
INT A0 - IBM ROM BASIC - used while in interpreter
INT A1 - IBM ROM BASIC - used while in interpreter
INT A2 - IBM ROM BASIC - used while in interpreter
INT A3 - IBM ROM BASIC - used while in interpreter
INT A4 - IBM ROM BASIC - used while in interpreter
INT A5 - IBM ROM BASIC - used while in interpreter
INT A6 - IBM ROM BASIC - used while in interpreter
INT A7 - IBM ROM BASIC - used while in interpreter
INT A8 - IBM ROM BASIC - used while in interpreter
INT A9 - IBM ROM BASIC - used while in interpreter
INT AA - IBM ROM BASIC - used while in interpreter
INT AB - IBM ROM BASIC - used while in interpreter
INT AC - IBM ROM BASIC - used while in interpreter
INT AD - IBM ROM BASIC - used while in interpreter
INT AE - IBM ROM BASIC - used while in interpreter
INT AF - IBM ROM BASIC - used while in interpreter
INT B0 - IBM ROM BASIC - used while in interpreter
INT B1 - IBM ROM BASIC - used while in interpreter
INT B2 - IBM ROM BASIC - used while in interpreter
INT B3 - IBM ROM BASIC - used while in interpreter
INT B4 - IBM ROM BASIC - used while in interpreter
INT B5 - IBM ROM BASIC - used while in interpreter
INT B6 - IBM ROM BASIC - used while in interpreter
INT B7 - IBM ROM BASIC - used while in interpreter
INT B8 - IBM ROM BASIC - used while in interpreter
INT B9 - IBM ROM BASIC - used while in interpreter
INT BA - IBM ROM BASIC - used while in interpreter
INT BB - IBM ROM BASIC - used while in interpreter
INT BC - IBM ROM BASIC - used while in interpreter
INT BD - IBM ROM BASIC - used while in interpreter
INT BE - IBM ROM BASIC - used while in interpreter
INT BF - IBM ROM BASIC - used while in interpreter
INT C0 - IBM ROM BASIC - used while in interpreter
INT C1 - IBM ROM BASIC - used while in interpreter
INT C2 - IBM ROM BASIC - used while in interpreter
INT C3 - IBM ROM BASIC - used while in interpreter
INT C4 - IBM ROM BASIC - used while in interpreter
INT C5 - IBM ROM BASIC - used while in interpreter
INT C6 - IBM ROM BASIC - used while in interpreter
INT C7 - IBM ROM BASIC - used while in interpreter
INT C8 - IBM ROM BASIC - used while in interpreter
INT C9 - IBM ROM BASIC - used while in interpreter
INT CA - IBM ROM BASIC - used while in interpreter
INT CB - IBM ROM BASIC - used while in interpreter
INT CC - IBM ROM BASIC - used while in interpreter
INT CD - IBM ROM BASIC - used while in interpreter
INT CE - IBM ROM BASIC - used while in interpreter
INT CF - IBM ROM BASIC - used while in interpreter
INT D0 - IBM ROM BASIC - used while in interpreter
INT D1 - IBM ROM BASIC - used while in interpreter
INT D2 - IBM ROM BASIC - used while in interpreter
INT D3 - IBM ROM BASIC - used while in interpreter
INT D4 - IBM ROM BASIC - used while in interpreter
INT D5 - IBM ROM BASIC - used while in interpreter
INT D6 - IBM ROM BASIC - used while in interpreter
INT D7 - IBM ROM BASIC - used while in interpreter
INT D8 - IBM ROM BASIC - used while in interpreter
INT D9 - IBM ROM BASIC - used while in interpreter
INT DA - IBM ROM BASIC - used while in interpreter
INT DB - IBM ROM BASIC - used while in interpreter
INT DC - IBM ROM BASIC - used while in interpreter
INT DD - IBM ROM BASIC - used while in interpreter
INT DE - IBM ROM BASIC - used while in interpreter
INT DF - IBM ROM BASIC - used while in interpreter
INT E0 - IBM ROM BASIC - used while in interpreter; multiple purposes
INT E1 - IBM ROM BASIC - used while in interpreter
INT E2 - IBM ROM BASIC - used while in interpreter
INT E3 - IBM ROM BASIC - used while in interpreter
INT E4 - IBM ROM BASIC - used while in interpreter
INT E5 - IBM ROM BASIC - used while in interpreter
INT E6 - IBM ROM BASIC - used while in interpreter
INT E7 - IBM ROM BASIC - used while in interpreter
INT E8 - IBM ROM BASIC - used while in interpreter
INT E9 - IBM ROM BASIC - used while in interpreter
INT EA - IBM ROM BASIC - used while in interpreter
INT EB - IBM ROM BASIC - used while in interpreter
INT EC - IBM ROM BASIC - used while in interpreter
INT ED - IBM ROM BASIC - used while in interpreter
INT EE - IBM ROM BASIC - used while in interpreter
INT EF - BASIC - ORIGINAL INT 09 VECTOR
INT F0 - BASICA.COM, GWBASIC, compiled BASIC - ORIGINAL INT 08 VECTOR
INT F1 - reserved for user interrupt
INT F2 - reserved for user interrupt
INT F3 - reserved for user interrupt
INT F4 - reserved for user interrupt
INT F5 - reserved for user interrupt
INT F6 - reserved for user interrupt
INT F7 - reserved for user interrupt
INT F8 - reserved for user interrupt
INT F9 - reserved for user interrupt
INT FA - reserved for user interrupt
INT FB - reserved for user interrupt
INT FC - reserved for user interrupt
INT FD - reserved for user interrupt
INT FE - AT/XT286/PS50+ - destroyed by return from protected mode
INT FF - AT/XT286/PS50+ - destroyed by return from protected mode