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Re: 6502 ML programming (fwd)
Forwarded message:
> Date: Thu, 9 Oct 1997 02:32:27 -0400
> From: [email protected] (Matthew Ghio)
> Subject: Re: 6502 ML programming
> Jim Choate <[email protected]> wrote:
> >
> > There in no 'DATA' construct in 6502 assembly.
> >
> > This is some sort of macro that either the assembler or programmer
> > defined. All official Rockwell/Commodore [1] 6502 assembly mnemonics are
> > three letter.
>
> True, but most assemblers would let you insert static data into the object
> file using various pseudo-ops like that.
>
>
> > Idealy a jump table was created that had the various target addresses for
> > your routines.
>
> Oh, those were fun to debug too...
>
>
> > The most efficient way to store data in 6502 is to put it in the first 256
> > bytes of ram, then it could be called in no more than 2 clock cycles.
>
> Actually that took three cycles. One to fetch the opcode, one to fetch the
> target address, and one to fetch the data byte. If you wanted to do it in
> two cycles, you had to write the data into the operand of the instruction
> that loaded it (self-modifying code).
Wow, we actualy agree on all points...that has to be a first.
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