IBM PC CONVERTIBLE

NO OVERFLOW
0208 PREP60:
0208 B7 00 BH,O ; CLEAR BH
020A 8A IE OOBC R
020E 88 87 OOBO R
02E2 88 OE OOBC R
MOV
MOV
MOV
MOV
BL,KILNMLTAIL ; MOV ORIGINAL TAIL POINTER TO BL
KB~MLBUFFER[BX] ,AL ; BUFFER SIC AT ORIGINAL TAIL POINTER
KB~MLTAIL,CL ; UPDATE TAIL POINTER
,
; ATTEMPT TO DEQUEUE KEYSTROKE AND TRANSLATE
02E6
PREP70:
02E6 F6 06 00B4 R
10 TEST
JNZ
CALL
JMP
KB~MLCNTL.XLATE_BUSY ; IS A XLATION ALREADY IN PROGRESS?
02EB 75 06
02ED E8 0319 R
02FO E9 0050 R
02F3
02F3
E9 0050 R
02F6
PREP90 JUMP I F ACTIVE
KYBD_XL T XLATE AND WRITE TO PORT 60
NMIH_EXIT EXIT KEYBOARD DATA ROUTINE
PREP90:
JMP
KYBD_PREP ENDP
GO TO 1ST LEVEL INTERRUPT HANDLER
PROCEDURE END
Keyboard Clear NMI (KYBD_CLR)
02F6
02F6
IE
02F7 07
*******************************************************************
KYBD_CLR - KEYBOARD CLEAR NMI PROCESSING
DESCRIPTION:
THIS ROUTINE IS JUMPED TO FROM THE FIRST LEVEL NMI INTERRUPT HANDLER
WHEN THE INTERRUPT IS THE RESULT OF PORT 60 BEING CLEARED.
A BUFFER EMPTY TEST IS MADE TO DETERMINE I F THERE ARE MORE KEY
SCAN CODES TO BE XLATED. IF THE BUFFER IS NOT EMPTY A CALL IS MADE TO
THE XLATE ROUTINE TO PROCESS THE KEY AT THE BUFFER HEAD.
THE FIRST LEVEL NMI INTERRUPT HANDLER SAVES REGISTERS AND MOVES THE
ADDRESS OF "DATA" TO THE DS REGISTER BEFORE IT JUMPS TO THIS ROUTINE.
ON EXIT THE FIRST LEVEL INTERRUPT HANDLER RESTORES REGISTERS.
INPUT: P60JlOLD_BYTE
OUTPUT: P60_HOLD_BYTE RESET
P60_LOADED RESET
CLILKEYBD OF PORT 6IH RESET
INTERNAL ROUTI NES: KYBDJL T
EXTERNAL ROUTINES: NONE
REGISTERS MODIFIED: NIA
INTERRUPTS: LEFT AS ARE
NORMAL EXIT: JMP NMIH_EXIT
*******************************************************************
NEAR
ASSUME DS:DATA
ASSUME ES:DATA
PUSH DS
POP ES
DATA POINTER TO ES
ROM BIOS 2-37