Problem erasing & re-using GM Proms

[Dave & Irina Eicher]

Hi Mike,

Vcc is: V = voltage, cc = collector.

It's the power supply pin for for the part.

Translation: The collector is one of three pins you would find on a bipolar
transistor, the emitter and base being the other two. For many years these
chips used transistors inside them. The Vcc pin became the standard
designation for the power supply pin on the chip. It supplies power to all
the various circuits in the chip. A typical circuit would have all the
emitters connected to ground and the collectors pulled up to Vcc through
some resistors. That is why they called it Vcc.

Todays more modern chips don't use bipolar transistors anymore, they use
FETs (Field effect transistors). FETs don't have emitters, bases, and
collectors, they have source, drain, and gate. Quite often on newer chips
you will see a Vdd rather than a Vcc because it is drains that are pulled up
to the power supply rather than collectors. But sometimes chip manufactures
retain the Vcc even though their chip doesn't have collectors just because
it has been called that for so long.

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.

More than you wanted to know?

regards,

Dave Eicher
319-295-8348 work deeicher at collins.rockwell.com
319-922-2626 home sailors at mwci.net
319-431-9001 cell

----- Original Message -----
From: <ECMnut at aol.com>
To: <gmecm at diy-efi.org>
Sent: Friday, January 05, 2001 6:59 AM
Subject: Re: Problem erasing & re-using GM Proms


> Yes!  it has an 014 on the chip.   Thanks to all for the insight
> on this subject.   What does VCC stand for?
> Mike V
>
> >  I had a 2732 that didn't program with a $170 (MSRP) programmer.  It
> >  programmed fine with a $17000 (MSRP) programmer.  The EPROM turned out
> >  to be a NatSemi/Fairchild 27C32B.  That chip wants to be programmed
with
> >  VCC = 6.25 volts.
> >
> >  Does your problem EPROM have the code 014 on it?  014 means NatSemi or
> >  Fairchild.  It's likely that many of their chips are picky about their
> >  programming conditions.
> >
> --------------------------------------------------------------------------
--
> To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
> in the body of a message (not the subject) to majordomo at lists.diy-efi.org
>
>

----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org