RE: 6502 Recompiled

From: Neil Bradley <>
Date: Fri Oct 15 2004 - 20:13:43 EDT

> > The code has been translated to C, and C is compilable on a LOT of
> > processor targets. Does that help?
> It does, thank you for taking the time. Thanks to you too, Graham.
> Let me see if I have the right vision of what you are doing. You have a
> 6502 recompiler that can take apart the original Asteroids game code and
> turn that code into C. You optimize that a bit, and then can burn that onto
> ROM's. Put the ROM's on a board with some newer processor (ARM or 68000
> maybe) and some modern RAM.

Or even some not so new processors.

The recompiler is basically a solution looking for a problem. I'm after
much bigger fish than just 6502 or Z80 games.

For the past 5 years or so, I've had the idea to do recompilation and have
been looking for an excuse to get started with it. Graham inspired me, so
in July I decided to start putting some of my theoretical ideas into

Even though these specific translations don't accomplish anything that
couldn't be done with software emulation, it does allow much weaker
processors to run them.

To give you an idea of the speed bump difference, MAME Runs Ms. Pacman at
around 800FPS. I can eek out 1800FPS under Retrocade with an assembly
language Z80 emulator core. With recompilation, the framerate is closer to
4500. Basically, almost all of the time is spent processing the graphics.
If I remove the graphics processing, the speed soars to over 32000 FPS.
Emulation runs somewhere around 18000FPS.

So consider this - an Atmel 66Mhz ARM chip doesn't have enough power in it
to emulate a 68000 *AND* do high res graphics (and sound) for games like
Toobin' or any other system 1 games. If I recompile the applications to
run natively, the performance becomes MUCH better and the odds of me
getting it to run on wimpier embedded system hardware gets much bigger.

> That setup will be functionally identical to
> the old Asteroids board, giving the same output ready to be fed to the
> Vector Generator.

Correct, it could be used for that application.

> Or does this cover the VG too?

Nope - just processor emulation.

> Are you looking to completely replace the old board with a new authentic,
> not emulated, one?

Nope, only trying to get the recompilation science a bit more honed down
for more complicated processors (like the 68000 and TMS 34010 to name a
few). There are still games in MAME that won't run full speed on even the
modest of processors, and that's one application of recompilation.


Neil Bradley "The true axis of evil in America is the brilliance of
Synthcom Systems, Inc. our marketing combined with the stupidity of our
                          people.." - Bill Maher
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Received on Fri Oct 15 20:13:44 2004

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