Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!pyramid!prls!gert
From: gert@prls.UUCP (Gert Slavenburg)
Newsgroups: comp.sys.atari.st
Subject: Re: upgrading a 520 ST to 1 meg - how about 2 meg?
Summary: where to find instructions
Keywords: 1M upgrade piggyback
Message-ID: <24135@prls.UUCP>
Date: 24 Jul 89 18:58:28 GMT
References: <706@lzaz.ATT.COM>
Reply-To: gert@prls.UUCP (Gert Slavenburg)
Organization: Philips Research Labs, Sunnyvale, California
Lines: 17

Several postings have recently asked about the old upgrade of a 520ST to 1M
by piggybacking 256k RAM chips. The initial upgrade description article was
from me and posted on comp.sys.atari.st in August 1985. I have no copy of the
original article anymore, but you can find a reproduction of it in BYTE :

  BYTE Feb 86, Vol 11, No 2, p. 372-376  (BIX Atari ST)

The original upgrade worked for me, and still does. However, many sources have
published improvements w.r.t. electrical signal quality. I believe it is a
good idea to use thicker wires than I originally suggested.
REMEMBER : ONLY DO THIS UPGRADE IF YOU HAVE HARDWARE EXPERIENCE AND HAVE
ACCESS TO SOME HARDWARE DEBUG TOOLS IN CASE IT FAILS. 

Gert Slavenburg (..!pyramid!prls!gert)

Disclaimer : Try this upgrade at your own risk. It will void your warranty
and may affect your rights to repair or exchange.