I response your request for a method to program 2708s, I put the documents
for a 1977 vintage programming card on my web site. The board was built by
"The Micro Works" for the SWTPC 6800 computer. The page includes the
schematic and the 6800 source code. The circuit and algorithm are simple.
http://www.swtpc.com/mholley/MicroWorks/B09_Index.htm
(Thanks to Jay West for hosting the site.)
I worked for Data I/O (the PROM programmer company) for a number of years
and the programming algorithms are different each IC vendor. Sometimes they
are very similar and sometimes incompatible. Often the algorithm would
change over the production run of an IC. Sometimes Data I/O would get a
request to change the algorithm because the semiconductor maker would have
several lots of parts that would not program correctly with existing
algorithm. (They may work but the EPROM did not pass life test or
something.) As soon as the updated algorithm was in the field the
semiconductor maker could ship the ICs they had been holding.
This is the reason they only wanted to release the programming data to a few
companies. It was easier for them to correct the algorithm if they could
contact everyone who had it.
Michael Holley
www.swtpc.com/mholley
----- Original Message -----
From: "Loboyko Steve" <sloboyko_at_yahoo.com>
To: <classiccmp_at_classiccmp.org>
Sent: Monday, May 06, 2002 8:21 AM
Subject: 2708 Programming Algorithm?
> I obtained a bunch of 2708 UVEPROM's, and I'd like to
> be able to program them. As you may know, they require
> a different algorithm than the 2716 and on, and three
> voltages, +5, +12, and -5.
>
> I'm building a little board that will program 1/2 (the
> upper or lower) of a 2716 to a 2708 (I can program
> 2716's). But I can't find a description of the
> algorithm that is detailed enough. What I think I know
> is:
>
> 1. The /OE line must be high
> 2. select address and data (start at addr 0)
> 3. bring PGM line from 0 to 27 volts for 1 mSec, then
> drop back to 0 (this seems very strange)
> 4. repeat 100 times per address (not all at once,
> increment the address lines and loop to avoid
> "overheating" a byte.
> 5. drop /OE and verify.
>
>
> Does anybody have an authoritative description, and a
> current requirement for the +5, +12, -5, and
> programming pulse? Thanks.
>
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Received on Wed May 08 2002 - 20:03:35 BST