Radio Shack TRS-80 Model III - Page 74

TRS-80
MODEL
$CSHIN
—
662/X0296'
Search for
Cassette
Header
and
Syne
Byte
Each
cassette
"record"
begins with
a header
consisting
of
a leader
sequence
and
synchronization
byte.
SCSHIN 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 other
registers
are
unchanged.
Sample
Z-80
Programming
The
following
program
reads
the tape
created
by the
SCSHWR
sample
program.
00048
! READ
A HFSE
SAGE FROM
If
8B0C
CDC901
00049
CALL
VDCLS
800F
3E0D
00050
LD
A
i
0DH
801 1
CD3300
0005
1
CALL
VDCHAR
80 i 4
CD4230
00052
CALL.
BET
CAB
8017
213B80
00053
LD
HI... i
MSG0
801
A
CD1B02
00054
CALL
VDL
I
NE
80
1
D
CD4900
00055
CALL.
KBWAIT
8020
216280
00056
LD
HL.TXT
8023
CD9602
00057
CALL
CBH
I
N
8026
CD3502
00058
LOOP
CALL
CS
I N
8029
77
00059
LD
(
HI.
)
. A
802A
23
00060
INC HL
802B
FE0D
00061
CP
0DH
802D
20F7
00062
JR
NZ
, LOOP
802F
CDF801
00063
CALL
CSOFF
8B32
216280
00064
LD
HLiTXT
8035
CD1B02
00065
CALL
VDL
I NE
8038
C3191A
00066
JP
READY
803B
50
00067
MSG0
DEFH
1
PREPARE
8061
0D
00068
DEFB
0DH
8062
00069
TXT
DEFS
256
~'E & STOP
ON
CAR RET
N
CLEAR
SCREEN
SKIP
A LINE
LET USER
SELECT
BAUD RATE
(HL) -CASSETTE
PROMPT
WAIT FOR
ANY KEY
(HL)
==256-
-BYTE
BUFFER
FIND
START OF
RECORD
INPUT
A BYTE
STORE
IT
POINT
TO NXT LOC.
WAS LAST BYTE
=
CAR
RET'N?
IF
NO. GET NXT
BYTE
IF
YES. TURN
OFF
CASSETTE
DISPLAY
THE
MESSAGE
AND QUIT
TAPE
TO
PLAY AND PRESS
ANY
KEY'
STORAGE
FOR TAPED
MESSA6EE
64