Radio Shack TRS-80 Operation Manual page 97

Computer Graphics Operation Manual
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Graphic Utilities Source Code Listings
INITG -- Initialize Model III Graphics Board
; GCLS -- Clear graphics screen
;
INITG LD
OUT
LD
~~l
~~2
~~3
~~4
~~S
~~6
~~7
~~8
~~9
~l~
~ll
~l2
~l3
~l4
~lS
~l6
~l7
~l8
~l9
~2~
~2l
~22
~23
~24
~2S
~26
~27
~28
~29
~3~
~3l
~32
~33
~34
~3S
~36
~37
~38
~39
~4~
~4l
~42
~43
~44
~4S
~46
GCLS
OUTER
INNER
INCY
INCXY
X
Y
WRITE
STATUS
PSECT
PUSH
PUSH
PUSH
CALL
LD
OUT
XOR
OUT
OUT
LD
LD
LD
OUT
DJNZ
LD
OUT
XOR
OUT
OUT
LD
OUT
XOR
LD
DJNZ
LD
OUT
POP
POP
POP
XOR
RET
EQU
EQU
EQU
EQU
EQU
EQU
~F~~~H
HL
DE
BC
INITG
A,INCY
(STATUS) ,A
A
(X) ,A
(Y) ,A
B,8~
C,B
B,239
(WRITE) ,A
INNER
A,INCXY
(STATUS) ,A
A
(WRITE),A
(Y) ,A
A,INCY
(STATUS) ,A
A
B,C
OUTER
A,~FFH
(STATUS) ,A
BC
DE
HL
A
7~H
3~H
8~H
8lH
82H
83H
A,l~H
(236),A
BC,lS
;Save registers
;Set graphics status:
; Graphics off, waits off, inc Y
;Set X
&
Y address to
~
;8~
X addresses
;239 Y addresses.
24~th
done after loop.
;Zero graphics memory
;Go clear next Y
;Set status to inc X & Y after write
;and clear last
(24~th)
Y address
;Set Y back to zero
;Reset status to inc Y only
;Go clear next X
;Set status to graphics, waits, no incs.
;Restore registers
;All done. Go back to caller.
;Turn on port
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