Radio Shack TRS-80 Model II Reference Manual page 245

Technical Information
Sample Program
This program demonstrates the use of the serial communications svc's in a
hypothetical' 'terminal" program.
,'; I"\MPL
E-::
PhlnGRAM FGK DEMnNsn~A T I NG CO
MM.
SVC' S
Tllu Sen 4, 19>10 15'38.35
PAGE' 1
THIS PROGRAM USES CHANNEL A.
AT LEAST I BYTE -I S AV AI LABLE FROM CHANNEL Al
GET IT AND DISPLAY IT
NOW SEE IF KEYBoARD CHARACTER IS AVAILABLE;
IF SO, TRANSMIT IT
1----------------------------------------------------------------
;
SCAN KEYBOARD SVC
PERFORM THE SVC FUNCTION
NO CHARACTER, KEEP LOOPING
ORIGIN FOR THE PROGRAM
CHAR COUNT RETURNED IN B, PUT INTO A
SEE IF ANY CHARACTERS AVAILABLE
IF NOT, TRY KEYBOARD INPUT
RECEIVE CHANNEL
A
SVC
PERFORM THE S¥C FUNCTION
LOST CARRIER ERROR EXIT
DISPLAY BYTE SVC (BYTE IS IN BI
PERFORM THE SVC FUNCTION
FUNCTION FOR GETTING CHARACTER COUNT
SUPERVISOR FUNCTlDN(SVC) FOR CHANNEL
A CONTROL
PERFORM THE FUNCTION
ERROR (uNKNOWN I
A,8
8
3,1
A ,I "0
A,qb
8
C,LOSTC
A.4
8
NZ,START
A,B
o
Z,TRYKE;
8
NZ, ERROR
3000H
LD
RST
LD
RST
JR
ORG
LO
CP
JR
RsT
JR
LD
PST
JR
~SETCOMJO MUST HAVE ALREADY BEEN DONE BEFORE THE
EXECUTION OF THIS Pq]GRAM. SAMPLE IS'
SETCiJM A=(JfJ0,7,E,I)
Al SEE IF A RECEIVED CHARACTER AVAILABLE
IF SO, DISPLAY ONTO VIDEO
B) SEE IF A KEYBOARD CHARACTER AVAILABLE
I F SO, TRANS~I T THE CHARACTER
CI LOOP BACK TO (AI
I - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
1
1
1
TRYKEJ •
START' LD
LD
1--------------------------------------------------------------
;
;
I
1
1----------------------------------------------------------------
I
SAMPLE USE OF THE COMMUNI CA TI ON CONTROL SUPERVI SOR
CALL. THIS PROGRAM wILL PERFORM THE FUNCTInNS OF
A RUDIMENTARY TERMINAL PROGRAM'
110
120
130
14"
150
16"
170
180
190
2'J0
21"
220
23"
24"
250
26"
270
28"
290
300
31"
320
33"
340
350
360
370
3R"
390
400
410
420
430
440
45"
460
47"
480
490
5"0
510
520
530
540
550
560
570
580
590
600
61'"
620
63"
640
3E08
CF
78
FE"'0
2808
0601
3E64
3E04
CF
20El
3E60
CF
3847
CF
2019
3011
3013
3007
3008
300A
3"00
3"02
3014
3016
3017
300C
300E
300F
3000
3004
3005
I
2
3
4
5
6
7
8
9
If'!
II
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
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46
47
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50
':>1
52
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54
281