Path: utzoo!utgpu!watmath!clyde!att!rutgers!mailrus!ulowell!cbmvax!daveh
From: daveh@cbmvax.UUCP (Dave Haynie)
Newsgroups: comp.sys.amiga
Subject: Re: Memory Expansion
Message-ID: <5664@cbmvax.UUCP>
Date: 11 Jan 89 18:40:02 GMT
References: <5663@cbmvax.UUCP>
Organization: Commodore Technology, West Chester, PA
Lines: 45

in article <5663@cbmvax.UUCP>, bill@cbmvax.UUCP (Bill Koester CATS) says:

> In article <11300002@hpfclr.HP.COM> guest@hpfclr.HP.COM (Guest account) writes:

>>     What is the cheapest way to upgrade the amiga 1000 to 1 Meg of memory.
>>I am not too excited about spending ~500 dollars for .5 Meg of memory.

>>Doug Quarnstrom

> If youre into hardware hacking and you don't mind blowing your warranty you
> can do the Amizing Computing memory hack. 

I did this same hack to my A1000, way back when, using Chris Erving's
original instructions, and it worked pretty well.  But you really have to
be careful (eg, know what you're doing, and then some).  My system worked
like a champ for about a year and a half, then the memory started failing.
Upon cracking the A1000 open, I found that one lead on one DRAM wasn't
soldered (I guess that's supposed to teach me not to hack hardware at
4 AM).  

On a related topic, the original modification put this RAM at $80000,
thich made the Amiga think it was CHIP memory, a real problem.  By the
time the Mr. Erving re-did the article for Amazing, he'd come up with a
hack to delay the visibility of this memory until after the OS set up
CHIP RAM, allowing on to the AddMem the extra 512K.  I didn't care for
that approach, so I created a hack of my own to change the decoding for
this memory such that it would appear at $C00000, just like on an A2000.
This article MAY still be up on some BBS system somewhere, and it's
supposed to be accompanied by an IFF picture of the final circuit.  It
requires modification of the daughterboard.

For cheap A2000 or A500 memory upgrades (beyond 1 meg), I wouldn't
recommend any such hack.  The A2000 DRAM bus is already reasonably full,
and with Fat Agnus instead of thin Agnus, you don't have access to as
many control signals, so the task would be much more difficult, if it
would work at all.  A company called Digitronics makes a assemble-it
yourself Zorro II DRAM board, which will hold 4 meg of chips, which is
to date the cheapest memory board I've seen.  This kit costs $100 and
includes everything but DRAM, and they also have an adaptor that'll let
this same board hook onto an A500.

-- 
Dave Haynie  "The 32 Bit Guy"     Commodore-Amiga  "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: D-DAVE H     BIX: hazy
              Amiga -- It's not just a job, it's an obsession