Re: Uprgading IIgs

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

Rubywand <rubywand@swbell.net> wrote:

> Randy Shackelford writes ...
> > 
> > A bit more base memory? Make that 4.5 times as much.
> 
>      This would apply only for the minimum, glorified IIe, no-expansion
> configuration. Fully expanded, the comparison for system RAM is 4.25MB to
> 5MB. In terms of running virtually all GS wares, it is not an important
> difference.

The point still stands that a bare bones ROM 1 is pretty useless (except
as a fancy IIe), but a bare bones ROM 3 has 1 MB of RAM, which is enough
to run GS/OS.  Many ROM 00/01 machines were never upgraded beyond 512K
(256K + 256K with the Apple IIgs Memory Expansion Card, which was
installed as standard) though they can be bumped up to 1.25MB if you can
find the memory.

(Incidentally, Apple Australia pulled a really nasty trick with the
memory card: instead of Apple's 1MB card with 256KB preinstalled, they
had their own small 256KB card that was not upgradable.  You had to buy
another card to upgrade the memory, resulting in a lot of completely
useless spare 256KB cards around Australia and New Zealand.)

> > More system in ROM? They have twice the ROM space.
> 
>      Nice; but, when you're booting a full System6 from hard disk, the
> advantage of the larger ROM is minimal.

There is still quite a lot of the toolbox being executed from ROM, so
you are saving more memory with a ROM 3.

Another advantage is that code runs faster from ROM than from RAM, and
the low-level drawing code (QuickDraw) is all in ROM in a ROM 3 machine,
but must be loaded into RAM if you boot System 5.0 or later on a ROM 1.
This gives the ROM 3 a quite noticeable advantage in the speed at which
it draws things in desktop programs.

If you use pre-System 5.0 on a ROM 1, you lose the major speed benefits
that were introduced to QuickDraw in System 5.0, so that doesn't help.

This speed benefit is much less significant if you have an accelerator,
as most of the code will be cached.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand