Re: ROM3 Upgrade

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

In article <3ok4h7$15k@moose.erie.net>,
Salvatore Buttice <qsilver@moose.erie.net> wrote:
> 
> : It looks like with ROM3 I only have to give up slot 1 or slot 2.  Is there 
> : anyplace where you can get the upgrade done anymore?  What's involved?
> : Is it just a ROM, or is it a motherboard change too?
> 
> ROM3 is a whole new motherboard. From the little I've seen, it's not 
> worth it at all, due to incompatibility problems with some of the 
> programs.

The programs that have problems are VERY small in number - I have
encountered a grand total of one program, and a newer version fixed
that.  On the other hand, I don't play many games.

The only programs that are likely to have problems are ones that have
broken Apple's rules for entry points and have called undocumented ROM
routines directly, or are assuming that certain undocumented system
variables or hooks are at particular locations.

One other problem that comes up with some programs is that they claim
to work in 1 megabyte, but actually need 1.25 megabytes (ROM 1
motherboard RAM plus 1MB expansion card).  The ROM 3 only has 1.125MB
unless you add a memory expansion card.


The ROM 3 has many minor improvements, the main one being the extra
megabyte of RAM.  It is also a little faster than a ROM 1 at running
QuickDraw-based software (i.e. all desktop software), because the
System 5 version of QuickDraw (which has major speed improvements) is
running from ROM, whereas it has to run from RAM in the ROM 1.  (The
IIgs runs code in ROM about 12% faster than code in RAM.)

My favourite improvement is the ability to set slot 4 to "your card"
and retain the use of the mouse in desktop programs (I never use it in
ProDOS-8 anyway).  One more free slot makes a huge difference. 

My second favourite improvement is the extended features in the system
monitor (CALL-151) - bank wrapping on dumps, auto-tracking of register
size changes in the disassembler, etc.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand