IBM AT 5170 Technical Reference page 353

IBM Personal Computer MACRO Assembler Vers,on 2.00 1-6
81052 ---- 06/10/85 8105 INTERRUPT ROUTINES 06- [0-85
499
500 CARR [AGE RETURN, L [NE FEED SU9ROUT I NE
50 I
502 0275 CRLF PROC
NEAR
503
SEND CR,LF TO FIRST PRINTER
504 0275 33 02
XOR OX,OX ASSUME FIRST PRINTER (OX: OJ
505 0277 88 0000
"OV
AX,CR
GET THE PR I NT CHARACTER COMMAND AND
506 027A CO 17
INT
17H
THE CARR I AGE RETURN CHARACTER
507 027C 88 OOOA
"OV
AX,LF
NOW GET THE LINE FEED AND
508 027F CD 17
INT 17H SEND IT TO THE BIOS PRINTER ROUTINE
509 0281 C3
RET
510 0282 CRLF
ENDP
5"
512
5"
514
:-- HAROWARE INT OB H -- ( IRQ LEVEL 0 ) -------­
5"
516
THIS ROUTINE HANDLES THE TIMER INTERRUPT FROM FROM CHANNEL 0 OF
5"
THE 8254 TIMER. [NPUT FREQUENCY IS 1.[9315 MHZ AND THE DIVISOR
51. IS 65536, RESULTING IN APPROXIMATELY 18.2 INTERRUPTS EYERY SECONO.
5 "
520
THE [NTERRUPT HANDLER MAINTAINS A COUNT (40:6C) OF INTERRUPTS SINCE
521 POWER ON TIME, WHICH MAY 9E USED TO ESTA8L1SH TIME OF DAY.
522
THE
I NTERRUPT HANDLER ALSO DECREMENTS THE MOTOR CONTROL COUNT
(40: 40 I
523
OF THE 0 I SKETTE, AND WHEN [T EXP I RES, WILL TURN OFF THE
524
DISKETTE MOTOR (s), AND RESET THE MOTOR RUNN I NG FLAGS.
525 THE INTERRUPT HANDLER WILL ALSO INYOI(E A USER ROUTINE THROUGH
526
INTERRUPT ICH AT EVERY T[ME TICK. THE USER MUST CODE A
527 ROUTINE AND PLACE THE CORRECT ADDRESS IN THE VECTOR TABLE.
52.
529
530 0282 TIMER [NT
1 PROC FAR
531 0282 FB - S1'I
INTERRUPT S BACK ON
532 0283 IE PUSH
OS
533 0284 50 PUSH
AX
534 0285 52
PUSH OX
SAVE MACHINE STATE
535 0286 E8 0000 E
CALL
DDS
ESTABLISH ADDRESSABILITY
536 0289 FF 06 006C R
INC II)TI MER LOW INCREMENT T I ME
T4 ­
537 0280 75 04
JNl
GO TO TEST DAY
538 028F FF 06 006E R
INC (tTl MER_HIGH INCREMENT HIGH WORD OF T [ME
539 0293
T4:
TEST DAY
540 0293 83 3E 006E R 18
C"P
4'TIMER HIGH,OIBH TEST FOR COUNT EQUALING 24 HOURS
541 0298 75 15
JNZ
T5 -
GO TO D I SKETTE_CTL
542 029A 81 3E 006C R 0080
C"P
'ltTIMER LOW,OSOH
543 02AO 75 00
JNZ
T5 -
GO TO 0 [SKETTE_CTL
544
545
T I MER HAS GONE 24 HOURS
546
547 02A2 2B CO
SUS AX,AX
548 02A4 A3 006E R
"DV
CO'TIMER _H I GH, AX
549 02A7 A3 006C R
"DV
'<tTIMER _LOW, AX
550 02AA C6 06 0070 R 0 I
"OV
'<tTl MER OFL,I
-
551
552 TEST FOR 01 SI(ETTE T I ME OUT
553
554 02AF
T5:
555 02AF FE OE 0040 R
DEC 'ltMOTOR COUNT DECREMENT DISKETTE MOTOR CONTROL
-
556 0283 75 08
JNZ T6
RETURN I F COUNT NOT OUT
557 0295 80 26 003F R FO
AND
(tMOTOR STATUS,OFOH
TURN OFF MOTOR RUNNING BITS
558 029A 80 OC
"OV
AL,OCH
559 029C 9A 03F2
"OV
DX,03F2H FDC CTL PORT
560 029F EE
OUT DX,AL TURN OFF THE MOTOR
561
562 02CO T6: T [MER T [CK [NTERRUPT
563 02CO CD I C INT TRANSFER CONTROL TO A USER ROUT I NE
564
565 02C2 5A
PDP
OX
RESTORE (OX)
566 02C3 80 20
"DV
AL,EO[
GET END OF I NTERRUPT MASK
567 02C5 FA
CLI D I SABLE [NTERRUPTS TILL STACK CLEARED
568 02C6 E6 20
OUT INTAOO ,AL END OF INTERRUPT TO 8259
569 02C8 58 PDP
AX
570 02C9 IF PDP
OS RESET MACHINE STATE
571 02CA CF
IRET RETURN FROM [NTERRUPT
572
573 02CB TIMER INT I ENDP
574
-
575 02CB
CODE ENDS
576
END
BIOS2 5-181