Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!psuvax1!rutgers!bpa!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga
Subject: Re: OS/Hardware memory limits
Message-ID: <12334@cbmvax.commodore.com>
Date: 5 Jun 90 23:13:22 GMT
References: <6506@vax1.acs.udel.EDU> <11700@cbmvax.commodore.com> <196.filbo@gorn.santa-cruz.ca.us>
Reply-To: daveh@cbmvax (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 46

In article <196.filbo@gorn.santa-cruz.ca.us> filbo@gorn.santa-cruz.ca.us (Bela Lubkin) writes:
>In <11700@cbmvax.commodore.com> Dave Haynie wrote:
>>[...] the up-to 1.75 Gigs of memory possible (assuming some serious
>>DRAM density improvements real soon) in the Zorro III bus.

>By eye, I guessed that a Zorro III board could hold 96MB of 1MBx4 ZIP
>chips.  

We fit about 64Megs worth (actually 16 Meg of 256K x 4, but they take up
the same space) on an A2630 daughterboard, just for experimentation's
sake (eg, Not A Product).  Squeezing more than that, plus the support logic,
buffers, etc. would be a trick.  Then again, with clever mechanical design,
you might build a double-decker board that fits in a single slot...

>19 such cards would fill the 1.75G address space.  Would a
>20-slot backplane have any chance of being reliable?  (I mean an A3000
>motherboard in a different case, with a 20-slot backplane replacing the
>standard 4 slots).  

I know a 10 slot backplane can stay in spec, at least for Zorro III cards.
I'm not sure about a 20 slot backplane.  In any case, the A3000 Buster chip
only supports 5 slots, though you could theoretically trade one last full
featured slot for an arbitrary number of slave-only cards without fast
interrupt support, sufficient for memory boards and the like.

If we hold out for 4MBx4 devices, a slight modification of the 8/32 Meg card
I wrote up for the upcoming DevCon could handle 128Megs, or 256Megs if you
up the density to the level of that daughterboard I mentioned.  So in the
forseeable future, you could stuff 1 Gig of expansion RAM into your A3000,
if the power supply holds out.  Looking at what these 1Mx4s go for these
days, prices better drop significantly before the 4Mx4s are ready.  But I
still have to figure out what to do with 32 extra megs.

>A fully loaded system would cost in the $.3-.5 million range.

World's Most Expensive Amiga.  When you buy that system, you get the A3000
logo in gold :-)

>Bela Lubkin   * *   //  filbo@gorn.santa-cruz.ca.us   CI$: 73047,1112 (slow)
>     @      * *    //  belal@sco.com  ...ucbvax!ucscc!{gorn!filbo,sco!belal}
>R Pentomino   *  \X/  Filbo @ Pyrzqxgl +1 408-476-4633, XBBS +1 408-476-4945

-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
	"I have been given the freedom to do as I see fit" -REM