Re: Questions about the //gs

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

In article <4ka28a$68@gap.cco.caltech.edu>,
Nathan Mates <nathan@cco.caltech.edu> wrote:
> 
>    Longer answer: more ram (512K or 1MB vs 256K), more ram (1MB vs
> 256K),

I think Nathan meant "more ROM" for the first of those.  The ROM 3
IIgs has 256KB of ROM, while the ROM 1 has 128KB.

The RAM is 1.125MB (1MB + 128KB) instead of 256KB.  You can add a 4MB
RAM card in both cases (and retain full DMA compatibility), so the ROM
3 can have more DMA-compatible RAM than the ROM 1.  Both machines have
an upper limit of 8 MB of "fast" RAM (plus the 128KB of "slow" RAM).

> slightly faster execution (especially on boot since more code
> is in rom and not loaded off disk)

This also applies to application startup.  The most significant effect
is on graphics output, because a faster version of QuickDraw is
included in ROM, whereas it has to be loaded into RAM on the ROM 1
(and code runs about 12% faster in ROM than in RAM on a IIgs).

> slightly cleaner sound, video boards (Video Overlay Card & Second
> Sight) can be in slots 1-6, not just 3. The main drawback is that a
> lot of early GS stuff (games and the like) are incompatible.

I must have missed most of these programs. I've only ever found one
program that I actually used which didn't work on the ROM 3, and it
was upgraded to support it.

Other ROM 3 improvements that come to mind:

- Keyboard Mouse and Sticky Keys are built into the computer (they can be
  added in software on a ROM 1, but cause compatibility problems with some
  programs; this doesn't apply on the ROM 3).

- You can set slot 4 to "Your Card" and retain the use of the mouse in
  GS/OS programs.

- AppleTalk support lives in the slot it actually uses, rather than stepping
  on bits of memory belonging to the actual slot.

- A lot of extra features in the System Monitor.

There are several other more obscure features as well.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand