[stella] Re: Emulating on a C64 or Amiga

Subject: [stella] Re: Emulating on a C64 or Amiga
From: Robin Harbron <macbeth@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 01 May 1997 13:46:19 -0400
Jim Nitchals wrote:

> A 6502/816 doing single-step by placing instructions into a temporary
> holding area then executing them can run at about 7% of real-time.  If
> doing address computation, masking of the 2600's high order address
> bits, etc you'd be lucky to get to 2% of realtime (times 20 for your
> fast '816, for a total of 40% of the speed of a real 2600.)

40% might not be all that bad... possibly worth doing.  But point
taken about the overhead.  I suppose it is faster letting the 65xx
execute the instructions like you said (that is what I was thinking)
then emulating each instruction like a non 65xx would have to do...

> I wrote a 6502-based package for doing fast code "emulation" for the
> purpose of debugging games while working at Electronic Arts.  It was
> too slow to bother with for any but the *worst, intractable* bugs.

Cool, working at EA, wow.

> And that was presuming hand-tuned assembly language.  Go to C, not the
> best language for the '816 (stack addressing modes are *SLOW*) and you're
> looking at a worthlessly slow solution.

Yup, I was only wanting the C source as a bit of a guide.  I'd
be writing it in assembly, I'm an awful lot better in it than C.  Thanks
for the comments.

Robin Harbron

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