17 Jul
2005
17 Jul
'05
1:45 a.m.
The 2147 us a 4kx1 part with speeds ranging from 70ns (in 1982)
to as fast as 45ns. In later years they got down to 25ns.
In the time frame they appeared in S100 boards ram was either
slow (greater than 250ns) or fast (sud 70ns) with the costs
to go with it. To build a 200ns board you needed ram faster
than 200ns to allow for propagation delays in the interface
and decode logic. So the 2147 was a choice.
I may add they ate current like mad when selected around 160ma
@5v and in standby it dropped to 20ma so board layout was had
to be very good.
Allison
Subject: RE: S100 RAM replacements - 2147's on Godbout boards
From: "Richard A. Cini" <rcini at optonline.net>
Date: Sat, 16 Jul 2005 20:26:28 -0400
To: "'General Discussion: On-Topic and Off-Topic Posts'" <cctalk
at classiccmp.org>
JDR listed it as 55nS which I thought was incredibly fast for an S100
system where 200nS was more common. It is indeed a 4kx1 chip according
to the product listing.
Rich
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org] On Behalf Of Barry Watzman
Sent: Saturday, July 16, 2005 1:19 PM
To: cctech at classiccmp.org
Subject: S100 RAM replacements - 2147's on Godbout boards
The 2147 was a mainframe cache static memory chip. It is extremely
fast, I think in the 35 nSec range, and uses less power than most of the
static memory chips more commonly used in S-100 systems, although being
a static memory chip, it is not "low power" by any stretch of the
imagination.
My recollection is that it's a 4kx1 chip with the same pinout as the TI
4044 and almost all of the other 4kx1 static memory chips, and that you
can actually substitute or mix 4044's and 2147's (the 4044's are nothing
like as fast, but in a 2 to 4 MHz S-100 system, you only need 150 to 250
nSec). However, please check this out, as it's possible that the 2147
was 1kx4 instead of 4kx1.
I don't know why no one else used this chip, but it is a fantastic
static memory chip.