Radio Shack TRS-80 Model 3 - Page 74

TRS-80 MODEL III
$CSHIN -662/X'0296'
Searchfor Cassette Headerand Sync Byte
Each cassette' 'record" begins with a header consisting ofa leader sequence and
synchronization byte. $CSHIN turns on the cassette drive and begins searching for
this header information. The subroutine returns to the calling program after the
sync-byte has been read.
Entry Conditions
None
Exit Conditions
A is altered. All otherregisters are unchanged.
SampleZ-80 Programming
The following program reads the tape created by the $CSHWR sample program.
000
L
.8
;
HEAD A ME~3SAC:iE FHOM TAPE
8.,:
fnop
ON CI'1F<"F<ET' N
B00C
CDC901
000
1
+9
CALL
VDCL.!:)
CL.FAH ~3cr~EEN
800F
:3E0D
00050
LD
A,0DH
B011 CDJ300
000~j 1
CALL VDCHAF< GI\I P In. L II'-ll:
B01. LI'
CDL.230 000:j :;~
CALL SET CAS LET
USEF<
bELE C1
B(.\UD FM'rE
8017 213Bl30
000:j:,3
LD
HL., MSG0
( 1'-11.. ) ,::C/:..Uf3E·r rE
PHOI'1PT
801A CD1B02 0005
L
•
CAL.L VDL INE
B01D
CD4900
00055 CALL
I·', B WI\ IT
WAIT FOH I~NY
f\EY
D020 :;;:~ 16280
000:)6
LD
HL" TXT
(HL) <::::.6-·BYTE
P,UFFEH
B0Z3 CD9602
00051 CALL CSHIN FII'W
S"rAF<T
OF
HECOHJ)
f)026
CD350:2' 00058
LOOP CALL.
Ct.'IN
INPUT A
BYTE
130::29 77 00059 L.D
(HL)
,A
STOHE
IT
802A 23 00060 INC
HL POINT
TO NXT LOC.
B02F:!.
FE0D
00061 CP l2lDH WI:..S tAU r
BYTE::::C(.\R··HF, T' N?
B02D 20F7 0006:;;:.:
<..1 H
NZ,lOOP
IF
NO, (-:iF 1
NXT EWTE
B02F
CDFB01
00063 CAL,L
CSOFF
IF
YEb,
TUHN OFF
CAUE3E::TTE.
EWl32
216:;;::B0
000tA
LD
HL,TXl
DHlPLAY THE MESSAGE
B035 CD1B02
00065
CALL VDL..INE
B038 C3191A 00066
JP
READY
AND
G1UIT
f:303B 50
00067 M~3G0 DEFM
., PHEPAHE
rAPE TO PLAY
,~ND
PRES~3 ANY
f\EY'
B061
0D 00068
DEFB 0DH
13062 00069 TXT DEFS 256
STORAGE FOR rAPED
MEf.)~3A6FE
12/6