IBM 5150 - Page 262

lOC OBJ
LINE
SOURCE
F8es 5043
tIDTOR_ON PROC NEAR
5044
j---------------- .. ----------------
5045
j PURPOSE:
5046
,
TO TURN ON CASSETTE MOTOR
5047
1-- --- ------ ---------- --- -- -- --- -_ ...
Fee5 [461
5048 IH AL,PORT_B
jREAD CASSETTE OUTPUT
F887 t4F7 5049
AHIJ AL.NOl OSH
; ClEAR BIT TO TURN ON MOTOR
~
F889 £661
5050
W3:
OUT PORT.B.AL
;WRITE IT OUT
FeSB 2AE4 5051
SUB
AH,AH
;ClEAR AH
F88D C3 S05Z
RET
5053 HOTDR.ON ENOP
5054
F ... 5055
MOTOR.OfF PROC HEAR
5056
i ............... -- --- ------ -----.---- ----- -----
5057 ; PURPOSE:
5058
5059
•
TO TURN CASSETTE MOTOR OFF
1------------------------ .. ----------- ...
'88£ E461
5060 IH
At.PORT_B
;READ CASSETTE OUTPUT
f890 oeoe 5061
OR At,.oeH ; SET BIT TO TURN OF f
F892
ESF5 5062
JHP
WJ
;WRITE IT, CLEAR ERROR, RETURN
5063
tIOTOR_OFF ENDP
Fa ..
5064
READ.BLOCK
PROe: NEAR
5065
; ----- -- -- -- -- ---- ----.- -- --- - -- -- -----------
5066 ; PURPOSE:
5067
I
TO READ 1 OR MORE 256 BYTE BLOCKS FROI1 CAsSEnE
5068
5069 I ON ENTRY:
5070 ES IS SEGMENT FOR MEMORY BUFFER (FOR COMPACT CODE)
5071
i
ex POINTS TO START OF MEMORY BUFFER
5012
I
CX COt~TAINS NUMBER OF BYTES TO READ
5073 f ON EXIT:
5074 ex POINTS 1 BYTE PAST LAST BYTE PUT IN MEM
5075 CX CONTAINS DECREMENTED BYTE COUNT
5076
ox CONTAINS NUMBER OF BYTES ACTUALLY READ
5077
5078
•
CAR~Y flAG IS CLEAR IF NO ERROR DETECTED
~
5079 CARRY flAG IS SET IF CRC ERROR DETECTED
5080
j -----------------------------_ .. _------------
F894 53 5081
PUSH BX
;SAVE BX
F895 51
5082 PUSH CX
;SAVE CX
F896 56
5083 PUSH 51
; SAVE 51
F897 BE0700 5084
HOV 51. 7
;
SET UP RETRY COUNT FOR LEADER
F89A Eet201 5085
CALl. BEGItCOP
; BEGIN By STARTING
MOTOR
F89D 5086 W4: ; SEARCH FOR LEADER
F89D E462 50S7
IN Al,PORT.C
;GET INTIAL VALUE
F89F 2410
50S8
ANO AL.OIOH
;MASK OFF EXTRANEOUS BITS
F8Al A26BOO
50S9 HOV LAST.VAL,AL ;SAVE IN Lot lAST.VAL
F8A4 BA7A3F
5090 MOV DX,16250 ; I OF TRANSITIONS TO LOOK FOR
5091
F8A7
5092 W5:
j WAIT.FOR.EDGE
F8A7
F606710080 5093 TEST
BIOS.BREAK. 80H
; CHECK FOR BREAK KEY
FSAt 7403
SO"
JZ W. I JUMP IF NO BREAK KEY
F8AE E98AOO 5095
JHP W17
~ JUMP IF BREAK KEY HIT
FS81 4A
SO"
5097
.. ,
DEC ox
F882 7503 5098
JHZ
W7 I JUMP IF BEGINNING OF LEADER
F8B4 E98400
5099 JHP W17 ; JUMP IF NO LHDER FOUND
5100
F887 E8C600 5101
1017:
CALL
READ.HAlF
.BIT
;IGNORE FIRST EDGE
FSBA BEB
5102
JCXZ
WS
; JUMP IF NO EDGE DETECTED
F8BC BA7803 5103
I10V OX.0378H
;
CHECK FOR HALF BITS
F8BF B90002 5104
MOV CX.ZOOH
.MUST HAVE AT LEAST THIS MANY ONE SIZE
5105 • PULSES BEFORE CHECKNG FOR SYNC BIT (0)
F8C! E421
5106
IH AL. 021H
• INTERRUPT
MASK REGISTER
Fac4 OC01 5107
OR AL.I
; DISABLE TIMER INTERRUPTS
~
f8C6 E621
5108
OUT
021H. AL
Feea 5109
1.18:
; SEARCH-LOR
F8C8 F6Q6710080 5110
TEST
BIOS_BREAK, 80H
;
CHECK FOR BREAK KEY
F8CD 756C 5111
JNZ
W17
; JlJ:1P IF BREAK KEY HIT
FeCF 51 5112 PUSH
CX
,SAVE REG CX
F800 ESAOOO
5113 CALL PEAD.HALF _BIT ;GET PULSE WIDTH
F6D3 OBC9
5114 OR CX. cx ; CHECK FOR TRANSITION
F8D5
59
5115 POP
CX
,RESTORE ONE BIT COUNTER
F806 74CS
5116
JZ
"4
1 JUMP IF NO TRANSITION
F8D8 3B03
5117 CHP
OX,BX
;CHECK
PULSE WIDTH
A-69