Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!att!lzaz!hcj
From: hcj@lzaz.ATT.COM (HC Johnson)
Newsgroups: comp.sys.atari.st
Subject: Re: RAM upgrades
Summary: 1 meg chips are narrower
Message-ID: <664@lzaz.ATT.COM>
Date: 29 Jun 89 12:47:52 GMT
References: <1280@hiatus.dec.com>
Organization: AT&T ISL Lincroft NJ USA
Lines: 26

In article <1280@hiatus.dec.com>, chad@norge.dec.com writes:
> 
> Hi
> 
> I would like to know if replacing one row of 256kb chips (16 chips)
> with one row of 1 megabit chips in a 1040 or 520STFM/upgraded will
> give the magic 2.5 meg RAM on the motherboard.  Is there a problem
> with this?
> 
> Also, I would like to DIY upgradethe old style 520 to 1 meg using
> any method not requiring an add on board.  That means most likely
> piggybacking.  Could someone please post what needs to be done to
> do this. Ie, any extra parts needed, any pins not to solder, any jumpers, etc...
 
1. 1 meg drams are narrow, 256k drams are wider.  there may also be a differ-
ence in pinouts.  my ezram-II uses 3 (thats three) plug in strips for
each ram position--wide for 256, narrow for 1 meg.

2. my second atari is a 520ST with a 1 meg upgrade.  each chip has piggybacked
on it a second 25k dram.  All pina are soldered except for the chip select.
It works, and there are no connectors to work loose like my ezram.

Howard C. Johnson
ATT Bell Labs
att!lzaz!hcj
hcj@lzaz.att.com