Re: Different versions of the ROM 3 IIgs - details

[dlyons@apple.com (David A Lyons)]

In article <CzIv94.Axv@actrix.gen.nz>,
David Empson <dempson@atlantis.actrix.gen.nz> wrote:
>Apple released two sets of ROMs for the "Apple IIgs with 1 megabyte of
>memory", popularly known as the "ROM 3 IIgs".
>
>The original set of ROMs has the serial numbers 341-0728 and 341-0729.
>These are very rare: I only know of one IIgs that has been confirmed
>to have these ROMs. 
>
>The revised ROMs have the serial numbers 341-0748 and 341-0737. These
>are by far the most common. 

"Released" is too strong a word here...there is only one real ROM 3
version.  Paul Bauer's GS is the only one I know of in the Real World to
have the bad version.  If there are others out there, I want to hear about
it!

Paul's machine came indirectly from an Apple field office, from where it
was apparently sold without having "real" ROMs.  Instead, it had the second-
to-final ROM version, which was -supposed- to be final (so at the top of
the screen it said "Apple IIgs" rather than a code name and version number,
as any earlier non-final ROM would have displayed).

When the QuickDraw-large-pixelmaps and ROMDISK bugs were fixed, some GSs
had already been manufactured with the bad ROM, but they all had their
ROMs replaced before being shipped.  *None* of the bad ROMs should have
made it into the retail channel, and as far as I know, none did.


>I have done a byte-for-byte comparison on the old and new ROMs, and
>have identified the differences.

Excellent work!  You got it exactly right.  To clarify:  Yes, the word
you guessed is just a checksum is exactly that.  The problem with ROMDISK
was that no calls were allowed through until it had been initialized by
an INIT call, but even the INIT call was not allowed through.  This went
unnoticed until the last minute because nobody had actually built a ROMDISK
card for the ROM 3 machines earlier.

-- 
Dave Lyons
Mr Tangent

On the net, I act as a private individual.