Re: IIGS ROM1/ROM3?

[dempson@actrix.gen.nz (David Empson)]

E.-R. Bruecklmeier <spamport@eric-bruecklmeier.de> wrote:

> aXis Computers schrieb:
> > 
> > Rom 01 was one of the 1st IIgs'' Only has 256k of onboard memory.
> > 
> > Rom 03 is the newer of the IIgs with 1.15megs of onboard memory..
> > 
> > Some programs will only RUN on rom 03 machines also..
> 
> Thx for your quick answer. Another last question: Are there programs
> which run only under ROM01?

Yes.  Probably more than those which only run on ROM 3.  In fact, I
can't think of anything I've encountered which only runs on ROM 3, and
only a very few programs which either require a ROM 1 or misbehave on
ROM 3.

If you run recent system software and have plenty of RAM, the vast
majority of programs work equally well on either machine.

ROM 0 is a different matter: this is the original IIgs firmware, which
was replaced by ROM 1.  It uses the same motherboard, so you can upgrade
the firmware (if you can get hold of the ROM - probably impossible now).
ROM 0 isn't supported by IIgs System 4.0 or later, and therefore isn't
supported by most IIgs applications released after  1988.  Some really
old programs only work on ROM 0, but many of them had updated versions
for compatibility with ROM 1.


Apart from the occasional compatibility glitch, the ROM 3 is generally
better than the ROM 1.

The increased RAM is the obvious benefit, though both machines have the
same upper bound of 8.125 MB of RAM.  There are some potential hardware
compatibility issues to do with DMA if you install a memory card which
supports more than 4 MB, so the ROM 3 also lets you have more RAM in
total without running into problems.

There are several other improvements, including increased flexibility in
slot configuration, better performance and additional RAM savings due to
more of the toolbox being in ROM, much less background noise in the
sound circuitry, and a socketed battery.

I suggest doing a search on DejaNews (or your favourite archive) for
past postings on this subject - I've posted all the major details
before, as have others.  It might have made it into the FAQ for this
group (I haven't checked)  - if it hasn't, then it should be there, as I
think it qualifies as a frequently asked question.

-- 
David Empson
dempson@actrix.gen.nz