S100 RAM replacements - 2147's on Godbout boards

[Allison]

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.
>
>