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From: XWUU@PURCCVM.BITNET
Newsgroups: comp.sys.cbm
Subject: RAM upgrade question
Message-ID: <90357.215753XWUU@PURCCVM.BITNET>
Date: 24 Dec 90 02:57:53 GMT
Organization: Purdue University
Lines: 32

I am ready to upgrade my 1764 REU to (at least) 512K.  I've read the
articles about how to do it and am anxious to get hold of geoWizard for
maximun GEOS power.

I know that I need eight 256Kx1 DRAM chips to upgrade to 512K, but which
ones?  I have a list in front of me that shows 256Kx1 DRAMS for a little
over $2 for one labelled 150ns (nanosecond) to one at just under $5 for
60ns operation. Do I need to be concerned about the "speed," or should I just
go for the least expensive?

A second question:
Instructions in "Beyond 512kb" by Andrew E. Mileski says that to bump my
REU over 512K requires that I "piggy-back" the DRAM IC's on top of the
chips mounted to the REU's circuit board.  Do I simply place the new chips
on the back of the old ones and stick the pins down along side of the old
pins?  Will both pins neatly fit the holes in the circuit board (or socket)?

I can easily see one additional row of IC's for each of the two banks on
the REU providing 1Meg, but to get 2Meg does one simply add yet another chip
to each stack?  Doesn't that get a little TALL on the board?  Where do the
pins on this 3rd row go?  How do you attach them to the previous chips?

Yes, I know...questions, questions, questions.  But some of you have done the
conversion and we'd like to know how you pulled it off.  The 512K expansion
looks like a cinch...the 1Meg-2Meg I'm not so sure about.

How 'bout it folks.  Any tips, hints, comments?

Kirk A. Janowiak
XWUU@PURCCVM

P.S.  HAPPY HOLIDAYS!!