IBM PC CONVERTIBLE Technical Reference page 176

0195 B4 01
0197 5B
0198 59
0199 5E
019A 5A
019B IF
019C CF
019D
019D 50
019E 42
019F EC
01AO A8 80
01A2 75 23
01A4 F8
01A5 B8 90FE
01A8 CD 15
01AA 72 13
01AC
01AC 2B C9
01AE
01AE EC
OlAF 8A EO
01B1 A8 80
01B3 75 12
01B5 E2 F7
01B7 A8 08
01B9 74 07
01BB FE CB
01BD 75 ED
01BF
01BF 80 CC 01
01C2
01C2 80 E4 F9
01C5 EB 19
01C7 58
01C8 4A
01C9 EE
01CA 42
01CB 50
01CC BO OD
01CE 42
01CF EE
01DO 24 FE
0102 EE
01D3 58
01D4
01D4 50
0105
BO: MOV AH,OlH
COMMON EXIT FOR ALL PRINTER FUNCTIONS
B1 :
POP
POP
POP
POP
IRET
POP
CX
SI
DX
DS
BX
PRINT THE CHARACTER IN (AL)
B2 :
PUSH
INC
AX
DX
CHECK FOR PRINTER BUSY
IN
TEST
JNZ
AL,DX
AL,NOLBUSY
B4
NO, RETURN TIMEOUT STATUS
RECOVER REGISTERS
RECOVER REGISTERS
SAVE VALUE TO PRINT
POINT TO STATUS PORT
GET STATUS
IS PRINTER CURRENTLY BUSY?
NO THEN OULSTROBE
NOTIFY OPERATING SYSTEM THAT A PRINTER BUSY WAIT IS IN AFFECT
B3 :
CLC
MOV
INT
JC
SUB
BL1:
IN
MOV
TEST
JNZ
LOOP
TEST
JZ
DEC
JNZ
AX,90FEH
15H
B3_2
CX, CX
AL,DX
AH,AL
AL,NOLBUSY
B4
B3_1
AL, NOLERROR
B3_3
BL
B3
***INT 15 DEVICE BUSY
FUNCTION 90 PRINTER ID
JUMP I F TIMEOUT OCCURRED
WAIT_BUSY
GET STATUS
STATUS TO AH ALSO
IS PRINTER CURRENTLY BUSY
NO, OULSTROBE
YES, TRY AGAIN
CHECK FOR I (0 ERROR
YES, JUMP
FINISHED 500 MS DELAY?
NO, DO AGAIN
BUSY TIMEOUT OCCURRED
YES, TIMEOUT
BL2:
OR
B3_3:
AND
JMP
AH,l
AH,OF9H
SHORT B7
SET ERROR FLAG
TURN OFF THE OTHER BITS
RETURN WITH ERROR FLAG SET
PRINTER IS NOT BUSY SO STROBE OUT CHARACTER
B4 :
DEC
OUT
INC
PUSH
MOV
INC
OUT
AND
OUT
POP
POP AX
DX
DX,AL
DX
AX
GET VALUE TO PRINT
POINT TO DATA REG
OUTPUT VALUE TO DATA REG
POINT TO STATUS PORT
SAVE VALUE TO PRINT
; OULSTROBE
AL,SELECT+NO_INIT+STROBE ; SET THE STROBE HIGH
OX STRB IS BIT 0 OF PORT C
DX,AL
AL,NOT STROBE SET THE STROBE LOW
DX,AL
AX RECOVER THE OUTPUT CHAR
PRINTER STATUS
B5:
PUSH
B6:
01D5 8B 94 0008 R MOV
INC
DX, PRINTEILBASE [S I]
OX
0109 42
ROM BIOS 2-151