Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!rutgers!cbmvax!cbmehq!babylon!rbabel
From: rbabel@babylon.rmt.sub.org (Ralph Babel)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: GVP 68030 board + bridgeboard == HUH?
Message-ID: <06429.AA06429@babylon.rmt.sub.org>
Date: 6 Mar 91 23:39:40 GMT
References: <709.27d4f185@vger.nsu.edu>
Reply-To: cbmvax.commodore.com!cbmehq!babylon!rbabel (Ralph Babel)
Lines: 42

In article <709.27d4f185@vger.nsu.edu>, manes@vger.nsu.edu
((Mark D. Manes), Norfolk State University) writes:

> I know that the Amiga 2000 is limited to 9mb of 16 bit
> memory.

Not quite. It's ~8.5 megs of _Zorro-II_autoconfig_memory_.
The memory width doesn't matter, though normal Zorro-II
boards are 16 bits wide, of course. But even 32-bit-wide
memory in the coprocessor slot can be made to behave like
normal Zorro-II autoconfig RAM, so it can in fact eat up
your autoconfig space.

> I know that when a bridgeboard is added you can only have
> a maximum of 6mb's of memory.

... provided your RAM expansion board permits that
configuration. Most boards don't, since 6 MB is really 4 MB
plus 2 MB (i.e. it must behave like two autoconfig devices).
GVP's Series-II SCSI+RAM for the A2000 does support 6 MB.

> I also _thought_ that if you wanted to have a bridgeboard
> and you wanted to go above 6mb of memory you could add an
> accellerator board and 32bit memory.  I _thought_ that
> this 32bit memory would be placed so that a bridgeboard
> would not interfer.  I guess this is not correct.

This depends on the design of the 32-bit RAM expansion. If
it is Zorro-II memory (added by expansion.library), then the
usual limits apply. All of GVP's original accelerator boards
behave that way.

The new A3050 in conjunction with the new RAM32 expansion
daughterboard, however, allows 4 MB of Zorro-II RAM _plus_ a
maximum of 16 MB (located at $01xxxxxx). This "Extended RAM"
is configured automatically by a ROM on GVP's board.

> Your thoughts are appreciated.

Hope this helps,

Ralph