>>Is it possible to run a program from Z80 SIO RAM? <<
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The answer is yes.? But not the way you want to do it.
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The keyboard and display is part of the issue and the other part
is that the rom that runs that is in that space.? The two are linked
and while ram is accessible your simple code depends on the rom
and the display to be available or it would not be visible.
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That code?
8000? ? ? 3C? ? ? ? ? ? ? ? ? ?inc ? A
8001? ? ? C2 00 80 ? ? ?Jp ? ?NZ,8000? ? ?; jump to 8000 if A ne 0
8004? ? ? ?03? ? ? ? ? ? ? ? ? ?inc ? BC? ? ? ? ? ? ? ; Inc BC
8005? ? ? ?C3 00 80 ? ? ?JMP ? 8000? ? ? ? ; go to 8000
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takes about 142 seconds to execute the double loop?
(roughly 570 million clock cycles).? the AC will overflow
to zero every 640us (approximately).
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The problem is if you are seeing BC increment that means
you have the monitors interrupt stopping it to show the
state on the display and its capturing the register and
placing on the display.? So that simple code is running
several hundred bytes of the rom to do what you see.
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Allison
