Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!dptg!lzaz!hcj
From: hcj@lzaz.ATT.COM (HC Johnson)
Newsgroups: comp.sys.atari.st
Subject: upgrading a 520 ST to 1 meg - how about 2 meg?
Message-ID: <706@lzaz.ATT.COM>
Date: 21 Jul 89 18:14:28 GMT
Organization: AT&T ISL Lincroft NJ USA
Lines: 25

A while back I mentioned I had a 520 ST that had been upgraded to 1 MEG
using piggy back soldering and have received several inquiries.

I also requested that if anyone had an old copy of how to do this that
they repost it. < SILENCE>.

Let it be known that I bought this ST USED, and the upgrade was already
in place.

In looking at it the  following is apparent.
1. all the pins, save 2 are soldered to the pin under the piggy back.
2. THERE ARE CUTS on the mother board.
3. Six (6) series resister lines go out to the drams.  3 go to the new
   (piggy) back ones.  the othe 3 , would I think, go the the original
   drams.

I will sketch the mess out, and post it, BUT I cannot guarantee I find all 
the cuts.  I'm sure this was common stuff 2-3 years ago.  Doesn't anyone
have real documentation on it?


Howard C. Johnson
ATT Bell Labs
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