Actually it's just the accumulator. The condition registers do not need
to be preserved between atomic chunks of code that implement
fundamental operations. (I know, human programmers do this for
maximum efficiency but it's not meant to be "right," it's meant to be
automate-able.)
Actually, context switching and multitasking would be possible
(albeit dreadfully slow) if there were more RAM. While the scheme
I am proposing has many inefficiencies I think it would provide enough
functionality to code a simple game -- the kind of thing people of my
age once did on TRS-80 model I's when those were the only computers
available for home use.
Of course, once we've got those youngsters hooked on the coolness
of making actual carts that work, we can seduce 'em into really
learning 6502 assembler and counting clock cycles to do it "right"
:-)
Besides, all of us would probably benefit from a way to do something
quick and simple on a lark.
--Roger Williams
----- Original Message -----
From: Adam Wozniak <adam@xxxxxxxxxxxxxxxx>
> On Mon, 26 Jan 2004, Roger Williams wrote:
> > Overhead most of the time will be 8 cycles (and use of the
> > accumulator). This check clears the way for 250 cycles of
> > code. During evaluation of a long expression a check might
> > need to be done that preserves the accumulator, which would
> > take a bit longer.
>
> accumulator and condition registers.
>
> If you're going to go that far, you might want to consider complete
> context switches / multitasking as well. =)
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