Radio Shack TRS-80 Operation Manual page 111

computer Graphics
Operation Manual
TRS-BO®
r--
JJ99 POP HL
1~~
XOR A
1~1
RET
1~2
X
EQU 80'H
1~3 y
EQU 81H
1~4
GRAPH
EQU 82H
1~5
STATUS EQU 83H
1~6
MASK DEFB
80'H
iMask
to use in extracting bits
1~7
BGMODE DEFB 12H
iControl byte: start graphics mode
1~8
BUFFER DEFS
24~
iPrinter data buffer
10'9 EGMODE DEFB
lEH iControl byte: end graphics mode
110' BPOS DEFB
0'
iBit position in printer buffer
I I I XLOC DEFB
0'
iCurrent
X location value
112
i
113
i
114
.
INITG --
Initialize Model III Graphics Board
,
115
.
,
116 INITG
LD
A,l~H
117
OUT
(236) ,A iTurn
on port
118
LD
BC,15
119
LD
HL,DATA
12~
LOOP LD A,B
iProgram CRTC chip for 80' by 24
121
OUT
(136),A
122 LD A, (HL)
123
OUT
(137) ,A
,,---"
124
INC
HL
125 INC B
126
LD
A,B
127 CP
C
128
JR NZ,LOOP
129 RET
13~
DATA DEFB 99
131 DEFB
8~
132
DEFB
85
132 DEFB 8
133
DEFB
25
134 DEFB 4
135
DEFB
24
136 DEFB 24
137 DEFB
JJ
138
DEFB 9
139 DEFB
~
14JJ DEFB
0'
141 DEFB
0'
142 DEFB
0'
143
DEFB
0'
144 DEFB
0'
145
146 END GPRINT
,~
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