On Wed, 8 Oct 1997, Clay Cowgill wrote:
> For example-- Space Fury. The code only once looks at input port 0xFA.
> (0xFA contains the right and left rotate button status.) Doesn't self test
> check those inputs too? Seems like if it did there'd need to be at least
> two accesses to 0xFA. Odd. Can you read an I/O port address indirectly on
> a Z-80?
>From "Timex Sinclari 2068, 1500, and 1000 Machine Language Programming and
Interfacing", page 197:
Immediate addressing is available the the accumulator (ie: register A),
while the B, C, D, E, H, and L registers use register indirect addressing.
The block I/O instructions are also register indirect.
In a word -- yes.
-Chris
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