[sebhc] 4044 memory chips

[Barry Watzman]

I was probably the source of that information.  I believe that the 2147,
4044 and MM5257 are all interchangeable to a large degree (I ***THINK***
that they have the same pinout, and being static memory, timing, while
significantly different, really isn't an issue).  What I'd suggest that you
do is verify the pinout for yourself from available documentation (the
2147's were used in several CompuPro boards whose manuals are available
online.  I believe that the CompuPro RAM 20 used them, among other boards).
Although even this would probably work, I would be inclined not to mix these
chip types on the same board, or even more so in the same bank.

You can do a lot better than $9 per chip by buying complete memory boards on
E-Bay.  For example, just a couple of days ago, some (several) Seattle
Computer products boards (16K S-100 memory boards (and it's a VERY GOOD
S-100 memory board, by the way)) were sold on E-Bay for about $50 per board.
While I consider that a high price for the boards (I dropped out of the
bidding in the mid $30's), each board has thirty-two (32) 4044's, so on a
cost per chip basis, it's under $2 per chip.  Boards using 4044's, 5257's
and 2147's appear quite often, you just have to know what to look for.
Basically, any S-100 static memory card with 16k or 32k per card is likely
to use one or another of these chips (a very few of them will use 2114's or
4045's, which are similar chips but organized 1kx4 instead of 4kx1).

Barry Watzman
Watzman at neo.rr.com


-----Original Message-----
From: sebhc-bounces at sebhc.org [mailto:sebhc-bounces at sebhc.org] On Behalf Of
Carroll Waddell
Sent: Friday, September 01, 2006 8:32 PM
To: sebhc at sebhc.org
Subject: [sebhc] 4044 memory chips

I hope someone can answer this question. seems as though I remember 
reading that the 2147 memory chip was the same as the 4044 chip, only 
much faster.
I just found a web site that has the 2147 chips for sale, but they are 
$9 each.
www.twobits.com/Parts/parts10.html/

If someone can verify that they are the same, we might a source of chips 
to populate the H8-1 memory boards.

Carroll
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