HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens

                INT 9 - Keyboard Interrupt (Hardware Handler)

       no input data

       related memory:

       40:17 = updates keyboard flag byte 0
       40:18 = updates keyboard flag byte 1
       40:1A = queue head ptr is set to buffer start if Ctrl-Break is hit
       40:1C = updates buffer tail pointer for each keystroke; sets
               queue tail ptr is set to queue start if Ctrl-Break is hit
       40:1E = updates keyboard buffer (32 bytes)
       40:71 = updates bit 7 of the BIOS break flag if Ctrl-Break is hit
       40:72 = updates reset flag with 1234H if Ctrl-Alt-Del pressed
       40:96 = indicates keyboard type (AT,PS/2)
       40:97 = updates keyboard LED flags (AT,PS/2)
       FFFF:0 = reboot code called if Ctrl-Alt-Del pressed

       related interrupts:

       INT 5     invoked if print screen key pressed
       INT 1B    invoked if Ctrl-Break key sequence pressed
       INT 15,85 invoked on AT if system request key is pressed
       INT 15,4F invoked on machines after PC/AT with AL = scan code

       - records key press and key release via IRQ1/8259 and
         stores scan codes in the BIOS buffer located at 40:1C
       - keyboard controllers also buffer data when interrupts are
         disabled at the 8259 interrupt controller
       - keyboard controller is capable of storing 16 keystrokes
         even when interrupts are disabled at the 8259
       - normal INT 9 execution takes approximately 500 microseconds;
         at least one standard XT BIOS is known to take up to 1.3
         milliseconds to execute

       - see   MAKE CODES   KB FLAGS

Esc or Alt-X to exit int 9 Home/PgUp/PgDn/End ←↑↓→
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