IBM PC CONVERTIBLE

0000
0000 IE
0001 53
0002 E8 0000 E
0005 OA E4
0007 74 10
0009 FE CC
OOOB 74 2B
0000 FE CC
OOOF 74 3B
0011 80 EC 02
0014 74 39
0016 EB 49 90
;
ASSUME cs: ROMCODE, CS : DATA
KYBD_IO PROC FAR
PUSH OS
PUSH BX
CALL DDS
OR AH,AH
JZ Kl
DEC AH
JZ K2
DEC AH
JZ K3
SUB AH,2
JZ K4
JMP KYBD_END
; SAVE CURRENT OS
; SAVE BX TEMPORARI L Y
; AH=O
; ASCILREAD
; AH=1
; ASCI LSTATUS
AH=2
SHI FLSTATUS
,AH=4
CLICI<-STATE
EXIT
; ----- READ THE KEY TO FIGURE OUT WHAT TO DO
0019
0019
FA
OOlA 8B IE OOIA R
OOlE 3B IE OOlC R
0022 75 08
Kl:
CLI
MOV
CMP
JNE
BX, BUFFEILHEAD
BX, BUFFER_TAIL
KLA
ISSUE KEYBOARD BUSY WAIT
0024 B8 9002
0027 CD 15
0029 FB
MOV
INT
STI
AX,09002H
ISH
; ASCI I READ
INTERRUPTS OFF
GET POINTER TO HEAD OF BUFFER
CHECK FOR HEAD = TAIL
JUMP IF SOMETHING IN BUFFER
CALL KEYBOARD BUSY HANDLER
INTERRUPTS ON
BIOS INT ISH WILL RETURN HERE WHEN HEAD <> TAIL
002A
EB ED
JMP Kl
; LOOP BACK TO WAIT FOR BFR NOT EMPTY
DATA IN KEYBOARD BUFFER
002C
KLA:
002C
8B 07 MOV AX, [BX] ; GET SCAN CODE AND ASCI I CODE
002E E8 03A4 R CALL PTILINC ; MOVE POINTER TO NEXT POSITION
0031 89 IE OOlA R MOV BUFFEILHEAD, BX ; STORE VALUE IN VARIABLE
0035
EB 2A 90 JMP KYBD_END
; RETURN
;----- ASCII STATUS
0038
K2:
0038 FA CLI I NTERRUPTS OFF
0039 8B IE OOlA R MOV
BX, BUFFER_HEAD
GET HEAD POINTER
0030 3B IE OOlC R CMP BX, BUFFEILTAIL I F EQUAL (Z=l) THEN NOTHING THERE
0041 8B 07 MOV AX, [BX]
0043
FB STI
RE-ENABLE INTERRUPTS
0044 5B
POP BX
RECOVER REGISTER
0045 IF
POP OS
; RECOVER SEGMENT
0046 CA 0002
RET 2
;
THROW AWAY FLAGS
,
;----- SHIFT STATUS
0049
K3:
0049 AO 0017 R
MOV
AL,KB_FLAG GET THE SHI FT STATUS FLAGS
004C
EB 13 90 JMP
KYBD_END RETURN
,
;----- CLICK STATE
004F K4:
004F OA CO OR AL,AL ; TURN OFF KEYBOARD CLICK?
0051 75 05 JNZ
K5
; JUMP FOR RANGE CHECK
0053 80 26 00B4 R F7 AND KB_NMLCNTL, NOT CLI CI<-ON ; TURN OFF CLI CK
0058
K5:
0058 3C 01 CMP AL,l ; RANGE CHECK
005A 75 05 JNE
KYBD_END
; NOT I N RANGE, RETURN
005C 80 OE 00B4 R 08 OR KB_NMLCNTL,CLICI<-ON ; TURN ON KEYBOARD CLICK
0061
KYBD_END:
0061 5B POP BX ; RECOVER REGISTER
ROM BIOS 2-67