Specifications

D:\D\inter61a\INTERRUP.A Saturday, January 08, 2011 11:31 AM

Notes: this IRQ may be masked by setting bit 1 on I/O port 21h

if the BIOS supports an enhanced (101/102-key) keyboard, it calls

INT 15/AH=4Fh after reading the scan code (see #00006) from the

keyboard and before further processing; all further processing uses

the scan code returned from INT 15/AH=4Fh

the default interrupt handler is at F000h:E987h in 100%-compatible

BIOSes

the interrupt handler performs the following actions for certain

special keystrokes:

Ctrl-Break clear keyboard buffer, place word 0000h in buffer,

invoke INT 1B, and set flag at 0040h:0071h

SysReq invoke INT 15/AH=85h (SysReq is often labeled SysRq)

Ctrl-Numlock place system in a tight wait loop until next INT 09

Ctrl-Alt-Del jump to BIOS startup code (either F000h:FFF0h or the

destination of the jump at that address)

Shift-PrtSc invoke INT 05

Ctrl-Alt-Plus (HP Vectra) enable keyclick

Ctrl-Alt-Plus (many clones) set clock speed to high

Ctrl-Alt-Minus (HP Vectra) reduce keyclick volume

Ctrl-Alt-Minus (many clones) set clock speed to low

Ctrl-Alt-SysReq (HP Vectra) generate hard reset

Ctrl-Alt-S (many clones) run BIOS setup program

Ctrl-Alt-Esc (many clones) run BIOS setup program

Ctrl-Alt-Ins (many clones) run BIOS setup program

Ctrl-Alt-LeftShift-GrayMinus (some clones) turn off system cache

Ctrl-Alt-LeftShift-GrayPlus (some clones) turn on system cache

DR DOS hooks this interrupt to control the cursor shape (underscore/

half block) for overwrite/insert mode

DR Multiuser DOS hooks this interrupt for cursor shape control and to

control whether Ctrl-Alt-Del reboots the current session or the

entire system

SeeAlso: INT 05"PRINT SCREEN",INT 0B"HP 95LX",INT 15/AH=4Fh,INT 15/AH=85h

SeeAlso: INT 16/AH=00h,INT 16/AH=10h,INT 1B,INT 2F/AX=A901h,INT 4A/AH=00h"TI"

SeeAlso: INT 51"DESQview",INT 59"DoubleDOS",INT 79"GO32"

(Table 00006)

Values for keyboard make/break (scan) code:

01h Esc 31h N

02h 1 ! 32h M

03h 2 @ 33h , < 63h F16

04h 3 # 34h . > 64h F17

-16-

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