Scan the keyboard to obtain scan codes

问题

So I'm learning how to make an OS. The problem is that every website says to scan the keyboard to obtain the scancodes in order to detect input. How do I 'scan' the keyboard? I know this question seems very ridiculous, but I really don't know how to do that, and I need help. I also have to mention that I googled it a lot.

回答1:

Example for polling the keyboard port without using an ISR (x86-CPU):

cli
mov  al, 2               ; dissable IRQ 1
out  21h, al
sti
;---------------------------------------------
AGAIN:
in   al, 64h             ; get status byte 
test al, 1               ; check outputbuffer
jz  short NOKEY
test al, 20h             ; PS2-Mouse byte?
jnz short NOKEY
in   al, 60h             ; get scancode (makecode or breakcode)

; place your code here for comparing.....

NOKEY:
jmp AGAIN
;---------------------------------------------
QUIT:
cli
xor  al, al              ; enable IRQ 1
out  21h, al
sti
;---------------------------------------------
; DATA 
TASTTAB DB 02h,03h,04h,05h,06h,07h,08h,09h,0Ah,0Bh,0Ch,0Dh
        DB 10h,11h,12h,13h,14h,15h,16h,17h,18h,19h,1Ah,1Bh,1Eh,1Fh
        DB 20h,21h,22h,23h,24h,25h,26h,27h,28h,29h,2Bh,2Ch,2Dh,2Eh,2Fh
        DB 30h,31h,32h,33h,34h,35h,39h
        DB 56h
tablen =  ($-TASTTAB)

TEXTTAB DB "1234567890ß'"      ; (using german letters)
        DB "qwertzuiopü+as"
        DB "dfghjklöä^#yxcv"
        DB "bnm,.- "
        DB "<"
textablen  =  ($-TEXTTAB)

Within an ISR simple use "in al, 60h" for to get the scancode.

来源：https://stackoverflow.com/questions/24988886/scan-the-keyboard-to-obtain-scan-codes