21MX proms (per request

Mike Stein mhs.stein at gmail.com
Thu Sep 10 13:50:46 CDT 2015

----- Original Message ----- 
From: "tony duell" <ard at p850ug1.demon.co.uk>
To: "General Discussion: On-Topic and Off-Topic 
Posts" <cctalk at classiccmp.org>
Sent: Thursday, September 10, 2015 2:29 PM
Subject: RE: 21MX proms (per request

> Your right, I didn't say that the 2716 was not a 
> single rail, just that it
> didn't have a separate Vpp and PGM pin. It was 
> programmed by turning
> Vpp on and off. I could be wrong that the 2732s 
> were that way as well.

The data sheet for the SGS-Thomson 2716 here :


says that you apply Vpp and keep it applied, set 
up address and data (with G/, pin 20, more
commonly called output enable, high and E/P low) 
and then program each location by taking the E/P 
(Pin 18, more commonly called chip enable) high 
for 50ms.

That is what I remember doing. You didn't have to 
pulse Vpp.


----- Reply -----

Yup; I still have a 2716 programmer I cobbled 
together for my PET and it just has a manual DIP 
switch (and LED) to turn Vpp on/off.before and 
after programming. To be sure, there were 
different versions but none pulsed Vpp AFAIK.


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