Problem erasing & re-using GM Proms

[Programmer]

Seems like most of the ones (factory GM) are a 27C32Q ... right ?

Lyndon.
----- Original Message -----
From: Ludis Langens <ludis at cruzers.com>
To: <gmecm at diy-efi.org>
Sent: Friday, January 05, 2001 12:48 PM
Subject: Re: Problem erasing & re-using GM Proms


> Dave & Irina Eicher wrote:
> >
> > Older EPROMs used to have a Vpp pin in addition to the Vcc. The Vpp pin
was
> > a programming voltage pin, voltage was applied to that pin only during
> > programming, not during normal read type operations. Newer chip designs
> > simply the interface by incorporating a programming voltage generator
> > circuit inside the chip, then the Vcc is the only power the chip needs.
>
> Heading off some confusion: the 27C32B I mentioned wants 6.25 volts on
> it's (normally 5 volt) Vcc pin, and 12.75 volts on it's Vpp pin during
programming.
>
> --
> Ludis Langens                               ludis (at) cruzers (dot) com
> Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/
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