Interrupt vector Description
00h |
CPU: Executed after an attempt to divide by zero or when the quotient does not fit in the destination |
01h |
CPU: Executed after every instruction while the trace flag is set |
02h |
CPU: NMI , used e.g. by POST for memory errors |
03h |
CPU: The lowest non-reserved interrupt, it is used exclusively for debugging, and the INT 03 handler is always implemented by a debugging program |
04h |
CPU: Numeric Overflow. Usually caused by the INTO instruction when the overflow flag is set. |
05h |
Executed when Shift-Print screen is pressed, as well as when the BOUND instruction detects a bound failure. |
06h |
CPU: Called when the Undefined Opcode (invalid instruction) exception occurs. Usually installed by the operating system. |
07h |
CPU: Called when an attempt was made to execute a floating-point instruction and no numeric coprocessor was available. |
08h |
IRQ0: Implemented by the system timing component; called 18.2 times per second (once every 55 ms) by the PIC |
09h |
IRQ1: Called after every key press and release (as well as during the time when a key is being held) |
0Bh |
IRQ3: Called by serial ports 2 and 4 (COM2/4) when in need of attention |
0Ch |
IRQ4: Called by serial ports 1 and 3 (COM1/3) when in need of attention |
0Dh |
IRQ5: Called by hard disk controller (PC/XT) or 2nd parallel port LPT2 (AT) when in need of attention |
0Eh |
IRQ6: Called by floppy disk controller when in need of attention |
0Fh |
IRQ7: Called by 1st parallel port LPT1 (printer) when in need of attention |
10h |
Video Services - installed by the BIOS or operating system; called by software programs AH
Description
00h |
Set Video Mode |
01h |
Set Cursor Shape |
02h |
Set Cursor Position |
03h |
Get Cursor Position And Shape |
04h |
Get Light Pen Position |
05h |
Set Display Page |
06h |
Clear/Scroll Screen Up |
07h |
Clear/Scroll Screen Down |
08h |
Read Character and Attribute at Cursor |
09h |
Write Character and Attribute at Cursor |
0Ah |
Write Character at Cursor |
0Bh |
Set Border Color |
0Eh |
Write Character in TTY Mode |
0Fh |
Get Video Mode |
13h |
Write String |
|
11h |
Installed by the BIOS; returns equipment list |
12h |
Installed by the BIOS or operating system; returns Conventional Memory Size |
13h |
Low Level Disk Services; installed by the BIOS or operating system; called by software programs AH
Description
00h |
Reset Disk Drives |
01h |
Check Drive Status |
02h |
Read Sectors From Drive |
03h |
Write Sectors To Drive |
04h |
Verify Sectors On Drive |
05h |
Format Track On Drive |
08h |
Get Drive Parameters |
09h |
Init Fixed Drive Parameters |
0Ch |
Seek To Specified Track |
0Dh |
Reset Fixed Disk Controller |
15h |
Get Drive Type |
16h |
Get Floppy Drive Media Change Status |
|
14h |
Routines for communicating via the serial port. Used by software programs. AH
Description
00h |
Serial Port Initialization |
01h |
Transmit Character |
02h |
Receive Character |
03h |
Status |
|
15h |
Miscellaneous (System services support routines) AH AL AX
Description
4Fh |
|
|
Keyboard Intercept |
83h |
|
|
Event Wait |
84h |
|
|
Read Joystick |
85h |
|
|
Sysreq Key Callout |
86h |
|
|
Wait |
87h |
|
|
Move Block |
88h |
|
|
Get Extended Memory Size |
C0h |
|
|
Get System Parameters |
C1h |
|
|
Get Extended BIOS Data Area Segment |
C2h |
|
|
Pointing Device Functions |
E8h |
01h |
E801h |
Get Extended Memory Size(Newer function, since 1994). Gives results for memory size above 64 Mb. |
E8h |
20h |
E820h |
Query System Address Map. The information returned from e820 supersedes what is returned from the older AX=E801h and AH=88h interfaces. |
|
16h |
Implemented by the BIOS or operating system. Provides routines to be called by software programs which communicate with the keyboard. AH
Description
00h |
Read Character |
01h |
Read Input Status |
02h |
Read Keyboard Shift Status |
10h |
Read Character Extended |
11h |
Read Input Status Extended |
12h |
Read Keyboard Shift Status Extended |
|
17h |
Print Services - used by software programs to communicate with the printer AH
Description
00h |
Print Character to Printer |
01h |
Initialize Printer |
02h |
Check Printer Status |
|
18h |
Execute Cassette BASIC: True IBM computers contain BASIC in the ROM to be interpreted and executed by this routine in the event of a boot failure (called by the BIOS) |
19h |
After POST this interrupt is used by BIOS to load the operating system. |
1Ah |
Real Time Clock Services - called by software programs to communicate with the RTC AH
Description
00h |
Read RTC |
01h |
Set RTC |
02h |
Read RTC Time |
03h |
Set RTC Time |
04h |
Read RTC Date |
05h |
Set RTC Date |
06h |
Set RTC Alarm |
07h |
Reset RTC Alarm |
|
1Bh |
Installed by the operating system; automatically called by INT 9 when Ctrl-Break has been pressed |
1Ch |
Called automatically by INT 08 ; available for use by software programs when a routine needs to be executed regularly |
1Dh |
Not to be called; simply a pointer to the VPT (Video Parameter Table), which contains data on video modes |
1Eh |
Not to be called; simply a pointer to the DPT (Diskette Parameter Table), containing a variety of information concerning the diskette drives |
1Fh |
Not to be called; simply a pointer to the VGCT (Video Graphics Character Table), which contains the data for ASCII characters 80h to FFh |
41h |
Address pointer: FDPT = Fixed Disk Parameter Table (1st hard drive) |
46h |
Address pointer: FDPT = Fixed Disk Parameter Table (2nd hard drive) |
4Ah |
Called by RTC for alarm |
70h |
IRQ8: Called by RTC |
74h |
IRQ12: Called by mouse |
75h |
IRQ13: Called by math coprocessor |
76h |
IRQ14: Called by primary IDE controller |
77h |
IRQ15: Called by secondary IDE controller |