Radio Shack TRS-80 Operation Manual page 94

Computer Graphics
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Operation Manual
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Options Programming
No.
1
2
3
4
5
6
7
Option
GRAPHICS/ALPHA*
NOT USED
XREG DEC/INC*
YREG DEC/INC*
X CLK RD*
Y CLK RD*
X CLK WR*
Y CLK WR*
Description
Turns graphics ON and OFF.
"1" turns graphics ON.
Selects whether X decrements
or increments. "1" selects
decrement.
Selects whether Y decrements
or increments. "1" selects
decrement.
If address clocking is
desired, a
"B"
clocks the X
address up or down AFTER a
Read depending on the status
of BIT 2.
If address clocking is
desired, a
"B"
clocks the Y
address up or down AFTER a
Read depending on the status
of BIT 3.
A
"B"
clocks AFTER a Write.
A
"B"
clocks AFTER a Wiite.
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Table 9. Options Programming
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