-----Original Message-----
From: allisonp_at_world.std.com <allisonp_at_world.std.com>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Thursday, June 24, 1999 6:28 AM
Subject: Re: More on the Compupro
>
>On Thu, 24 Jun 1999, Richard Erlacher wrote:
>
>> I've been watching this thread with some interest, as I'm curious how
large
>> a board with 512Kbytes in 4116's would be. I've got some boards
downstairs
>> which have sites for 288 4116's on each. That's 576KB, though it's
>> organized as 64-bit words with off-board SECDED which makes it 512 KBytes
>
>The board in question obviously has 4164s on it or it's only 1/4 the size
>indicated.
>
That's what I concluded as well, though the originator of this thread has
said at least once they were 4116's. I'e got an 8MB "ramdisk" board I built
back in about '85 when the 256k's were new. This board is populated with a
few LSI samples I got, together with a 4MBx18 section literally hacked (with
a bandsaw) from a client's application circuit and tacked to the S-100
board. The packages were the "zip" package, which allowed for pretty dense
layout. If I ever find this circuit again, I intend to rework the logic,
since the memory is actually organized 1MBx72 bits, and I have a
now-obsolete LSI from TI, the 74AS6364A, which is a gigantic LSI used to
perform SECDED. Since it corrects and propagates in only 10 ns, I want to
build in a hardware error scrubbing circuit and maybe a battery backup
scheme. The board's still more than half empty, since the memory is on two
mezzanine boards. - Dick
>
>Compupro made a M-drive, a 512k ram disk using 4164 devices. I have one
>of these and it works quite well.
>
>Allison
>
>
Received on Thu Jun 24 1999 - 15:06:12 BST