Re: looking for souping hardware

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

In article <treiter-2403961514080001@10.0.2.15>,
Toby Reiter <treiter@comet.net> wrote:
> In article <4il0at$tk7@taco.cc.ncsu.edu>, perrywat@unity.ncsu.edu (Julian
> P Watson) wrote:
> >Good news to hear, John.  Can a IIgs, ROM 01, use the 8 meg card and use 
> >all 8 MB of memory??  I have a 4 MB card now and would love to have 
> >another 4 MB of memory.  However, I understand that the ROM 01 is limited 
> >to 4 MB of memory as tops.
>
> As far as I know, there is no differnce between the Rom o1 and Rom 03 in
> terms of the amount of extra memory they can have...the memory expansion
> port can only handle up to 8 megs.

Actually, the memory expansion slot is limited to 4 MB, unless the
card decodes the bank address directly, in which case it is possible
to expand the total "fast" RAM address space to 8 MB (including any
RAM on the motherboard).

Assuming you use a 4 MB card, the ROM 1 can be expanded up to 4.125 MB
of fast RAM, and the ROM 3 can be expanded up to 5 MB of fast RAM.
(Both have an additional 128KB of slow RAM.)

The 8 MB limit is primarily due to the Memory Manager toolset.  It
doesn't attempt to examine memory beyond bank $7F when it is
determining the memory size.

It is also quite likely that there are hardware restrictions (e.g. a
deliberate design limit in the FPI chip) which prevents the memory
expansion slot from being accessed beyond bank $7F.

> And on a Rom 04 IIgs, wouldn't upwards of that (10megs or more) be possible?

The ROM 4 prototype didn't have a memory expansion slot at all - just
2 MB of RAM on the motherboard and some SIMM sockets (four of them, or
possibly only three, as it was based on the ROM 03 design).


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