Re: RFC : SOME IDEAS FOR THE APPLE II FPGA'ers

[scott@alfter.diespammersdie.us (Scott Alfter)]

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In article <4455f006$0$16984$5a62ac22@per-qv1-newsreader-01.iinet.net.au>,
Mark McDougall  <msmcdoug@no.spam.iinet> wrote:
>Jorge Chamorro Bieling wrote:
>
>> 1.- Think of page 0 addresses as registers, you should put them where 
>> they belong: inside the processor, not in memory. 
>
>Knowing very little about the 6502 instruction set off the top of my head - 
>is it possible to access page 0 using 'non-page 0 addressing modes or 
>instructions'? If so, that will be a problem.

It is...LDA $0000 (AD 00 00) is just as valid an instruction as LDA $00 (A5
00).  It takes one more byte to store and one more cycle to execute, so
unless you found those characteristics somehow useful (tweaking the timing
of a loop, for instance), you probably wouldn't have used them.

Minor trivia: entering LDA $0000 into the mini-assembler produces LDA $00 as
output instead.

  _/_
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