19 May
2005
19 May
'05
10:18 p.m.
---------------Original Message:
Date: Wed, 18 May 2005 14:21:03 -0500
From: "Randy McLaughlin" <cctalk at randy482.com>
Subject: Re: Disk archival techniques
<snip>
Using one manufacturer as an example - Cromemco used bipolar PROMs and made
their own numbers - 749XX. This makes it confusing but easy to spot when
seen. They would use the chips on multiple boards keeping the same
programming by chipnumber i.e. 74901 could be used on a floppy controller or
memory card and still be interchangeable (I just made up an example but I've
seen common 749XX across different types of cards).
Randy
www.s100-manuals.com
-------------Reply:
As a matter of fact, I just dumped several Cromemco PROMs a while ago for archival use;
what's the recommendation for 4 bit PROMs? 8 bits with hex F's in the upper
nibble, or?
And are we going to be able to find blank bipolar PROMS or PALs in 10 or 20 years?
mike
24 May
24 May
11:07 a.m.
From: "M H Stein" <dm561 at torfree.net>
Sent: Friday, May 20, 2005 12:18 AM
---------------Original Message:
Date: Wed, 18 May 2005 14:21:03 -0500
From: "Randy McLaughlin" <cctalk at randy482.com>
<snip>
Using one manufacturer as an example - Cromemco used bipolar PROMs and
made
their own numbers - 749XX. This makes it confusing but easy to spot when
seen. They would use the chips on multiple boards keeping the same
programming by chipnumber i.e. 74901 could be used on a floppy controller
or
memory card and still be interchangeable (I just made up an example but
I've
seen common 749XX across different types of cards).
Randy
www.s100-manuals.com
-------------Reply:
As a matter of fact, I just dumped several Cromemco PROMs a while ago for
archival use;
what's the recommendation for 4 bit PROMs? 8 bits with hex F's in the
upper nibble, or?
And are we going to be able to find blank bipolar PROMS or PALs in 10 or
20 years?
mike
In the future as today an adaptor to current technology is possible, but
only if the data is saved.
How many of us have ever created a daughter card to adapt a flash ROM to a
board needing a 2708 etc.
Randy
www.s100-manuals.com
4:38 p.m.
As a matter of fact, I just dumped several Cromemco
PROMs a while ago
for archival use;
what's the recommendation for 4 bit PROMs? 8 bits with hex F's in the
upper nibble, or?
I normally use 8 bits per location, data in the low bits, top 4 bits
don't-cares (eitehr 0 or F is common), but all the same for a given dump.
Anybody seeing that in the future who knows that it's a dump of a 4-bit
wide device will soon realise that as the top 4 bits of each byte are
constant, it's likely that the useful data is the bottom 4 bits only.
And are we going to be able to find blank bipolar PROMS or PALs in 10
or 20 years?
Prbably not, but there _will_ be fast-enough memory devices that can be
programmed and kludged into the board in place of the failed part. The
fact that you might only be using the bottom 32 bytes of an 8Mbyte part
won;t be a worry I guess.
-tony
7152
days inactive
7156
days old
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