IBM XT 5160 Technical Reference page 290

LI NE SOURCE (BIOS FOR THE IBM PERSONAL COMPUTER XT) I 1 /08/82
5-143
WA I T FOR THE INTERRUPT
I F ERROR, RETURN IT
SENSE I NTERRUPT STATUS COMMAND
RETURN TO CALLER
CHK2_ERROR
ERROR RETURN CODE
READ I N THE RESULTS
CHK2 RETURN
GET THE FIRST STATUS BYTE
ISOLATE THE BITS
TEST FOR CORRECT VALUE
I F ERROR, GO MARK I T
GOOD RETURN
GET THE BYTES / SECTOR PARM
OUTPUT THE HIGH 4 BITS TO
THE PAGE REG I STER
USE AS SH I FT COUNT (0= 128, I =256 ETC)
MUL T I PL Y BY CORRECT AMOUNT
- 1 FOR DMA VALUE
SAVE COUNT VALUE
LOW BYTE OF COUNT
HIGH BYTE OF COUNT
I NTERRUPTS BACK ON
RECOVER COUNT VALUE
RECOVER ADDRESS VALUE
ADD, TEST FOR 64K OVERFLOW
RECOVER REG I STER
MODE FOR 8237
I NIT I AL I ZE THE 0 I SKETTE CHANNEL
RETURN TO CALLER,
CFL SET BY ABOVE I F ERROR
CARRY MEANS HIGH 4 BI TS MUST BE INC
SAVE START ADDRESS
OUTPUT LOW ADDRESS
NUMBER OF SECTORS
TIMES 256 INTO AX
SECTORS • 128 I NTO AX
OUTPUT HIGH ADDRESS
GET HIGH 4 BITS
OUTPUT THE MODE BYTE
GET THE ES VALUE
SHIFT COUNT
ROTATE LEFT
GET HIGHEST NYBLE OF ES TO CH
ZERO THE LOW NYBBLE FROM SEGMENT
TEST FOR CARRY FROM ADDITION
SAVE THE REGISTER
NO MORE INTERRUPTS
SET THE FIRST /LAST F /F
ENDP
CX
AX
AX,CX
CX
AL,2
DMA+ I O,AL
AH,DH
AL,AL
AX,1
AX
BX,6
GET PARM
CL,AH
AX
AX,CL
AX
AX
DMA+5, AL
AL,AH
DMA+5, AL
AX
DMA+4, AL
AL,AH
DMA+4,AL
AL,CH
AL,OFH
081H,AL
DMA+ 12,AL
AX
AX
DMA+ II ,AL
AX,ES
CL,4
AX,CL
CH,AL
AL,OFOH
AX,BX
J33
CH
MOV
SUB
SHR
PUSH
MOV
CALL
MOV
POP
SHL
DEC
PUSH
OUT
MOV
OUT
STI
POP
POP
ADD
POP
MOV
OUT
RET
PUSH
OUT
MOV
OUT
MOV
AND
OUT
DE TERM I NE COUNT
PC-XT System BIOS (11/08/82)
RET
OR
STC
RET
CHK_STAT_2
J34:
J35:
.
-----------------------------------------------------------------------
CHK STAT 2 PROC NEAR
- CALL WAIT INT
JC J34 -
MOV AH,08H
CALL NEC OUTPUT
CALL RESOL TS
JC J34
MOV AL,NEC STATUS
AND AL,060R
CMP AL,060H
JZ J35
CLC
J33:
NONE
OUTPUT
CY = 0 SUCCESS
CY I FAILURE -- ERROR IS IN DISKETTE_STATUS
(AX) DESTROYED
INPUT
( AL ) MODE BYTE FOR THE DMA
(ES:BX) ADDRESS TO READ/WRITE THE DATA
OUTPUT
(AX) DESTROYED
DMA SETUP
- TH I S ROUT I NE SETS UP THE DMA FOR READ / WR I TE / VER I FY OPERAT IONS.
CHK STAT 2
THIS ROUT I NE HANDLES THE INTERRUPT RECE I VED AFTER A
RECALl BRATE , SEEK, OR RE SET TO THE ADAPTER.
THE I NTERRUPT IS WA I TED FOR, THE I NTERRUPT STATUS SENSED,
AND THE RESULT RETURNED TO THE CALLER.
INPUT
.
-----------------------------------------------------------------------
DMA SETUP PROC NEAR
- PUSH CX
CLI
OUT
PUSH
POP
OUT
MOV
MOV
ROL
MOV
AND
ADD
JNC
INC
2812
2813
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290 I
2902
2903
LaC OBJECT
EFI2
EFI2 E81EOO
EFI5 7214
EFI7 B408
EFI9 E825FF
EFIC E84AOO
EFIF 720A
EF21 A04200
EF24 2460
EF26 3C60
EF28 1402
EF2A F8
EF2B
EF2B C3
EF2C
EF2C 800E410040
EF31 F9
EF32 C3
EEED 8AE6
EEEF 2ACO
EEFI DIE8
EEF3 50
EEF4 BB0600
EEF7 E872FF
EEFA 8ACC
EEFC 58
EEFD D3EO
EEFF 48
EFOO 50
EFO I E605
EF03 8AC4
EF05 E605
EF07 FB
EF08 59
EF09 58
EFOA 03C I
EFOC 59
EFOD B002
EFOF E60A
EFII C3
EEC8
EEC8 51
EEC9 FA
EECA E60C
EECC 50
EECD 58
EECE E60B
EEDO 8CCO
EED2 BI04
EED4 D3CO
EED6 8AE8
EED8 24FO
EEDA 03C3
EEOC 7302
EEDE FEC5
EEEO
EEEO 50
EEEI E604
EEE3 8AC4
EEE5 E604
EEE7 8AC5
EEE9 240F
EEEB E681