IBM PC CONVERTIBLE Technical Reference page 64

ASSUME OS: DATA
ASSUME ES: DATA
SCAN CODE BUFFER PROCESSING
0319 XL TlO:
0319 E8 0000 E CALL
; DISABLE ALL INTERRUPTS
031C F6 06 00B4 R 80 TEST
JNZ
KB_NMLCNTL, P60_LOADED ; IS PORT 60 CURRENTLY LOADED?
0321 75 00
XL Tl3 ; YES THEN EXIT THE ROUTINE
,
; PORT 60 IS NOT LOADED SO CHECK QUEUE FOR ANY KEYS
0323 8A IE OOBB R
0327 3A IE OOBC R
; BUFFER HEAD DISPLACEMENT
; I S BUFFER EMPTY
032B 75 06
MOV
CMP
JNE
BL, KLNMLHEAD
BL,KB_NMLTAIL
XL Tl4 ; YES, GO TO BUFFER EMPTY ENTRY
PORT 60 IS NOT LOADED AND NO KEYS IN QUEUE SO FIX NUM_LOCK STATUS
AND EXIT
0320 E8 0524 R'
CALL
RE-ENABLE KEYBOARD NMIS AND EXIT THE ROUTINE
0330 E9 0523 R XLTl3: JMP XL T100
DEQUEUE THE SCAN CODE FROM THE NMI QUEUE
0333 80 OE 00B4 R 10 XLTl4: OR KB_NMLCNTL,XLATLBUSY ; SET KEY XLATE IN PROCESS
0338 B7 00 MOV BH,O ; CLEAR BH - BL IS BUFFER HEAD DISP
033A 8A 87 OOBD R MOV AL,KB_NMLBUFFER[BXl ; GET SCAN CODE FROM BUFFER
033E FE C3 INC BL INCREMENT HEAD POINTER
0340 80 FB 10 CMP BL,KB_NMLBLTH IS BL
=
END OF BUFFER +1
0343 72 02 JB XL Tl5 JUMP I F NOT PAST END OF BUFFER
0345 B3 00 MOV BL,O PAST END - SET TO START
0347 XLTl5:
0347 88 IE OOBB R MOV
KB_NMLHEAD,BL
UPDATE BUFFER HEAD
; START OF SCAN CODE TRANSLATION
ENABLE NMIS AND RESTORE INTERRUPT STATE TO PRE-NMI CONDITION
;
-
-
-
----
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- -- - - - -
-
-- - - - -- - - - - - -- - - - -
- -
- -- - ---
034B E8 076E R CALL NMLCYCLE CYCLE NMI MASK, RESTORE INT FLAGS
034E 8A EO MOV AH,AL AH
<===
ORIGINAL NMI SC
0350 3C FF CMP AL,OFFH KEYBOARD OVERRUN ?
0352
75 14
JNE XL Tl8
NO, GO LOOK FOR FUNCTION KEY
KEYBOARD OVERRUN DETECTED
0354 C7 06 00B5 R 0000
MOV
B_PENDl,O ; RESET BREAK PENDING FLAGS
035A C7 06 00B7 R 0000 MOV B_PEND2,0 ; RESET BREAK PENDING FLAGS
0360 80 26 00B4 R BF AND K B_NM LCNTL, NOT FUNCSTATE ; CLEAR FUNCTION STATE
0365 E9 050C R JMP XL T90 ; OVERRUN, GO WRITE PORT 60
; CHECK IF SC IS FOR A BAS E KEY ONLY
0368 XLTl8:
0368 80 E4 80 AND AH , BR EALB IT AH
<===
BREAK BIT OF NMI SC
036B 8A DO MOV DL,AL DL
<===
ORIGINAL NMI SC
036D 24 7F AND AL,NOT BREALBIT AL
<===
NMI SC W/O BREAK BIT
036F 8D IE 0000 LEA BX, KBNMLTBL SCAN CODE TABLE - NMI TO PCl
0373 2E: D7 XLAT KBNMLTBL XLATE NMI SC TO PC! SC
0375 A8 80 TEST AL ,80H BASE KEY ONLY?
0377 75 03 JNZ XL Tl9 NO, JUMP AROUND
0379 E9 04DE R JMP
XL T60_1
YES, JUMP TO BASE KEY PROCESS
IF THIS IS THE FUNCTION KEY, SET/RESET FUNCTION STATE
ROM BIOS 2-39