Might as well answer to the list as well :-)
Hi!
<< >How is the value determined using indirect-x and indirect-y?
>How is the address determined using indirect-x and indirect-y?
The value is accessed address minus $F000
The address to write to is the address that is accessed 3 or 4 cycles after
the access to $F0xx.
>>
OK, lets look at the following
cmp 1000
nop
lda (2000),y // don't worry about the nonsense addresses
// at location 2000 is 1234 stored
// y=6
is that like a BASIC:
poke 0,2000
poke 0,2006
poke 0,1240 (that's what I do now, it 'seems' to be OK)
?
<<
Also you should keep in mind, that the controll byte at $FFF8 allways is
write enabled.
Does that mean, that every access to $fff8 is allways a write?
(I'm sure that I haven't implemented that yet...)
>PS. My stella now runs Frogger, Dragonstomper, Rabbit and a few others
> It doesn't run (well) Suicide Mission, Phasor Patrol, Communists...
Does this include the load capability of Dragonstomper or do you mean only
the first part?
Ciao, Eckhard Stolberg
>>
Well, I haven't played Dragonstomper till it loaded another part, but I'd
guess that
it works OK, since survival island works...
<<
Again intructions don't matter. The value is stored to the address that is
accessed 3 or 4 processor cycles after the access to $F0xx. I am not sure
about the timing though. But indirect accesses work too and they first have
to read the address from the zeropage, which takes some cycles. Also in my
programm I have to put a NOP between the two accesses, like
>>
Does that mean, that the address has to follow after a certain number of
cycles?
I mean, if I insert 100 NOPs after a 'lda RAM', that a 'cmp f123' wouldn't be
a poke anymore?
(I certainly haven't included cycle counters for RAM access yet!)
Thanks and bye
Chris
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