21MX proms (per request

[tony duell]

> 
> 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 : 

http://ee-classes.usc.edu/ee459/library/datasheets/2716.pdf

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
(Pin 18, more commonly called chip enable) high for 50ms. 

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

-tony