Re: What is the difference between ROM 1 and ROM 3 IIgs computers?

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

Pim Blokland <pDOTblokland@spcgroup.nl> wrote:

> David Empson wrote:
> > 
> > > >> Rom 1 is more compatible, and Rom 3 is slightly faster (because
> > > >> the System Disk needs to patch less code).
> > 
> > More than slightly.  It is quite noticeable.  The main area of
> > improvement is the QuickDraw II changes in System 5.0, which are in the
> > ROM in a ROM 3 machine, but must be loaded into RAM on a ROM 1 (most of
> > the low-level drawing bottleneck routines).
> 
> I don't have both a ROM 01 and a ROM 3 machine, so I can't check the
> speed difference, but I do know this:
> Virtually all toolboxes that come with GS/OS 6.01 have a newer version
> number than the toolboxes that the ROM 3 machine has in ROM.

Yes, but this is usually done by patching the appropriate routines (from
the TOOL.SETUP and TS3 files), including the routine which reports the
version number.  I think there are two (or thereabouts) toolsets that
are completely patched out.  However, they are high level ones that
don't have much in the way of heavily used (hence speed-critical) code.

> This means that any desktop application that uses the formal tool call
> entries to start up the tools, load the tools from the system disk into
> RAM. So a ROM 3 machine may be faster under system 5.0, but not so under
> 6.01.

Loading is another issue.  I was primarily talking about the drawing
speed of the system AFTER the toolsets are loaded.  The QuickDraw
"bottleneck" routines are the key to this, and they are in ROM on a ROM
3, even under System 6.0.x.

If you want to consider toolset loading speed: there will be a
difference of two (ish) toolsets loaded from disk under System 6, and
even then only if the toolset in question is not already in memory (it
usually will be).  All the patches are installed at boot time, so this
is only an issue for the fully loaded toolsets (and ROM 3 will still
beat the pants of ROM 1 in this area, because it has about five major
toolsets that don't need to be loaded).

I doubt this is particularly noticeable.

ROM 3's boot time might be a fraction longer, because it has more
toolsets to patch, but I haven't timed each machine with an identical
configuration.

> And as far as I know, another difference between the ROM 01 and the ROM
> 3 GS, that has been neglected in this thread, is that the ROM 3 has a
> different motherboard layout, which results in a "cleaner" sound output
> signal, due to less noise from other components.

I didn't notice whether it was mentioned in this thread, but it has been
mentioned recently.

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