IBM PC CONVERTIBLE

0268 80 26 0016 R 7F
0260 BO 00
AND
MOV
OUT
IN
OR
OUT
BIOS3TATUS,NOT DSP_BLANKED ; RESET FLAG
AL,O
026F E6 74 LCD_INDX,AL
0271 E4 75
AL,LCLDATA ; GET DISPLAY CONTROL REG
0273 OC 60 AL,SYNCENABLE+PANELENABLE ; TURN ON PANEL
LCD_DATA,AL 0275 E6 75
SET KEYBOARD ACTIVE FLAG (FOR THIS PERIOD)
0277
PREP_12:
0277 80 OE 0016 R 20
027C 80 26 0015 R BF
OR
AND
BIOS3TATUS,KYBD~CTIVE ; INDICATE KEYBOARD IS ACTIVE
BALSTATUS,NOT LOW_BAT.JlOLD ; RESET LOW BTRY HOLD FLAG
; ..... -- ..... _------ ------ --- --- -- --- .. ---- ----- -- ---- -- -------------------
; A KEYBOARD DATA READY NMI OCCURED. READING THE DATA RESETS THE DATA
; READY NMI REQUEST.
; ... ---------_ ...... -----_ ... -- -_ ... ---- --- ---- ------- ---- ---- -- ---- ..... -- ------
0281 E4 7D
IN AL,KBNMLDATA
; READ SCAN CODE
DETERMINE IF A KEY STROKE CLICK IS REQUIRED FOR THIS KEY.
A CLICK IS SOUNDED ON THE MAKE OF ALL KEYS EXCEPT THE MAKES OF KEYS
THAT ARE GENERATED BY TYPAMATIC MODE.
0283 A8 80
0285 74 07
TEST AL, BREAK...BIT
JZ PREP20
; IS THIS A 'MAKE' SCAN CODE?
; YES, GO TO CLICK PROCESSING
; ALLOW ANY BREAK KEY TO CLEAR LASLCLICK...KEY
0287 C6 06 OOBA R 00 MOV LASLCLI CK...KEY , 0
; YES, CLEAR LASLCLI CK...KEY
028C EB 23 JMP SHORT PREP29 ; GO TO BUFFER PROCESSING
028E PREP20:
028E
38 06 OOBA R
CMP LASLCLI CK...KEY , AL ; T -MATIC KEY IF = TO LAST KEY MAKE
0292 74 10
JE PREP29 ; IF TYPAMATIC SKIP CLICK
FIRST KEY HIT - NOT TYPAMATIC
;
0294 A2 OOBA R
MOV LASLCLI CK...KEY , AL ; THIS KEY IS NOW LASLCLICK...KEY
0297 F6 06 00B4 R 08
TEST KB_NMLCNTL,CLICK...ON ; IS AUDIO FEEDBACK ENABLED?
029C 74 13
JZ PREP29 NO, GO TO BUFFER PROCESSING
029E BB 0001 MOV
BX,lH ; DURATION OF CLICK
02A1 B9 0020 MOV CX,20H
; FREQUENCY OF CLICK
02A4 8A DO MOV DL,AL
; SAVE KEYSTROKE
02A6 E8 0759 R CALL SPKR_ON
; FORCE SPEAKER ON
02A9 E8 0000 E CALL KB_NOISE
; OUTPUT KEY STROKE CLICK
02AC E8 0762 R CALL SPKILRESTORE
; RESTORE SPEAKER STATE
02AF 8A C2 MOV AL,DL
; RESTORE AL
PROCESS KEY
02B1 PREP29 :
02B1 SA 2E OOBB R MOV CH,KLNMLHEAD BUFFER HEAD TO CH
02B5 8A OE OOBC R MOV
CL,KB_NMLTAIL
BUFFER TAIL TO CL.·
02B9 FE C1 INC CL INCREMENT TAIL POINTER
02BB 80 F9 10 CMP
CL,KB_NMLBLTH
; IS CL = END OF BUFFER +l
02BE 72 02 JB PREP50 ; JUMP I F NOT PAST END OF BUFFER
02CO B1 00 MOV CL,O PAST END - SET TO START
02C2 PREP50:
02C2 3A E9 CMP CH,CL HAS TAIL REACHED HEAD - OVERFLOW
02C4 75 12 JNE PREP60 JUMP I F NOT OVERFLOW
KEYBOARD NMI BUFFER OVERFLOW
,
02C6 C6 06 OOBB R 00 MOV
KB_NMLHEAD,O
; BUFFER OVERFLOW - PURGE BUFFER
02CB C6 06 OOBC R 01 MOV
KB_NMLTAIL,l
;
POSITION FOR OVERFLOW INDICATOR
02DO C6 06 OOBD R FF MOV
KB_NMLBUFFER,OFFH
; OVERFLOW INDICATOR TO BUFFER HEAD
0205
EB OF 90
JMP
PREP70
2-36 ROM BIOS