68010 (was Re: Mac IIci)

From: Ethan Dicks <erd_6502_at_yahoo.com>
Date: Wed Jan 16 12:44:55 2002

--- Gooijen H <GOOI_at_oce.nl> wrote:
> Indeed, the 68000 and 68010 pushed the same amount of data onto the
> stack, but the 68010 produced more different types of stack-frames than
> the 68000.

I suppose it's all a matter of semantics - different stack frames vs.
different amounts of bytes pushed on a bus error... I'd quote chapter
and verse, but I forgot to dig out my 68K manuals last night.

> If you wanted to speed up the ATARI-ST you could replace the 68000 with
> an 68010, but you needed to patch TOS. Otherwise the O.S. crashed.

Same for the Amiga, except no patch required for Kickstart/AmigaDOS 1.2
and up (I forget about 1.0 or 1.1). The one way to prove you had a
68010 in your Amiga was to run the old calc program - it did a MOVEcc
instruction which is privved on the 68010. There was an optional
patch that would intercept that trap and emulate the instruction, but
since you weren't supposed to execute that instruction directly (there
was an approved way of doing it), the patch wasn't required for ordinary

> Nice was the fact that the 68000 and the 68010 are *pin-compatible*.

Yep. We got to reuse all of our expensive 68000 diagnostic hardware
when we made a 68010 design (building a pin-swabber for our one and
only 68008 design was a pain and some stuff didn't work right, but
it was good enough for the task at hand).

> I know, because my StarShip first ran on a 6802, then a 68000 and then on
> a 68010.


> I had to re-write a small part of the embedded OS that handles
> the stack-frame processing. Tight-loops (2 instruction) are cached.


> [My StarShip runs on a 68020 at 30 MHz. now]

Nice. That'd be cool to see in person. I have been kicking around
a similar project since 1987 - mine was two seats, more like a Space
Shuttle flight sim, made from scrapped DEC RK05 shells (the innards had
been cleaned out by me for spares at work, at direction of my boss).
The guts of what I had finished were two 9" PETs for display, and a
single 12" 80-col PET. Nice stuff, but I ended up putting the PET guts
back in the PETs. They became too useful to squirrel away in a sim
cabinet. These days, I'd use commodity hardware. Still have the
shells - but they are dismantled and stacked in the attic. :-(


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Received on Wed Jan 16 2002 - 12:44:55 GMT

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