bright@dataio.UUCP (Walter Bright) (11/19/86)
Here's my latest list of the uses of interrupts on the PC. Many thanks to the people who mailed me information. Interrupts on IBM PCs, ATs, etc. In () are what defines the use of the interrupt. INT 0 Divide Error INT 1 Single-Step INT 2 NMI INT 3 1 Byte Software interrupt (0CCh instruction) INT 4 Overflow (INTO instruction) INT 5 Print Screen (BIOS) INT 6-7 Reserved (IBM PC) INT 8-0F Vectored hardware lines IRQ0-IRQ7 (IBM PC) INT 8 Timer interrupt INT 9 Keyboard interrupt INT A Reserved (IBM PC) INT B COM2: Interrupt INT C COM1: Interrupt (IBM PC) INT D Fixed disk / CRT vertical retrace INT E Diskette interrupt INT F PPI interrupt INT 10 Video I/O (BIOS) INT 11 Equipment Determination (BIOS) INT 12 Memory Size (BIOS) INT 13 Diskette I/O (BIOS) INT 14 RS232 I/O (BIOS) INT 15 Cassette I/O (BIOS) INT 16 Keyboard I/O (BIOS) INT 17 Printer I/O (BIOS) INT 18 Transfer to ROM Basic (BIOS) INT 19 Boot Strap Loader (BIOS) INT 1A Time of Day (BIOS) INT 1B Ctrl-Break Handler (BIOS) INT 1C Clock Tick (BIOS) INT 1D Video Parameters (BIOS) INT 1E Diskette Parameters (BIOS) INT 1F Graphics Character Extensions (BIOS) INT 20 Program Termination (MS-DOS) INT 21 MS-DOS Functions (MS-DOS) INT 22 Terminate Address (MS-DOS) INT 23 Ctrl-Break Exit Address (MS-DOS) INT 24 Critical Error Handler Vector (MS-DOS) INT 25 Absolute Disk Read (MS-DOS) INT 26 Absolute Disk Write (MS-DOS) INT 27 Terminate But Stay Resident (MS-DOS) INT 28-2E MS-DOS Internal Routines (MS-DOS) INT 28 Scheduler (MS-DOS) INT 29 Print character to video (?) INT 2A NETBIOS interface INT 2E Load COMMAND.COM (MS-DOS) INT 2F Multiplex interrupt (MS-DOS 3.0 or later) INT 30-3F Reserved for MS-DOS (MS-DOS) INT 31 Fixed disk bios (?) INT 33 Microsoft Mouse Driver (MOUSE.SYS and MOUSE.COM) INT 3F Overlay Interrupt (Microsoft LINK.EXE) INT 40-5F Reserved (IBM) INT 40 Diskette pointer save area for Fixed Disk (BIOS) INT 41 Fixed Disk Parameters for first disk INT 42 Original INT 10h vector (EGA BIOS) INT 46 Fixed Disk Parameters for second disk (AT BIOS) INT 4A Alarm (IBM AT BIOS) INT 50 Periodic and alarm interrupts from non-volatile timer (IBM AT) INT 5A Cluster (BIOS) INT 5B Used by Cluster Program INT 5C IBM PC Network (PC Network BIOS) INT 60-67 Reserved for user program interrupts (IBM) INT 67 Expanded Memory Management handler (LIM EMS Spec) INT 68-6F Not used (IBM) INT 6C DOS 3.2 Real time clock update INT 70-77 IRQ8-IRQ15 (IBM AT) INT 70 Realtime clock (IBM AT) INT 78-7F Not used (IBM) INT 80-85 Reserved by BASIC INT 86-F0 Used by BASIC interpreter while BASIC is running INT F8 Interval Timer INT FA USART Ready INT FB USART Rx Ready