BOUNCE diy_efi: Admin request (fwd)

[thergen at svn.net]

I suppose it could be a page addressed eprom like an intel 27513.  Pins 11
and 12 double as bank select lines using pin 27 as we~ and pin 1 is rst~.

I'm assuming the eprom is not in _any_ type of carrier.  There should be
some info in the archives on read protect schemes when some type of
carrier is used.

It looks like the mail may have bounced to admin because the machine name
doesn't match the ip address: kojab.ar.com.au (dialup173.ar.com.au
[203.18.148.173]) 


On Wed, 11 Nov 1998, Orin Eman wrote:

> > >From diy_efi-owner at esl.eng.ohio-state.edu  Wed Nov 11 16:18:26 1998
> > Received: from ar.ar.com.au (root at ar.ar.com.au [203.18.148.1])
> > 	by esl.eng.ohio-state.edu (8.8.7/8.8.7) with ESMTP id QAA21764
> > 	for <diy_efi at efi332.eng.ohio-state.edu>; Wed, 11 Nov 1998 16:18:23 -0500
> > Received: from kojab.ar.com.au (dialup173.ar.com.au [203.18.148.173])
> > 	by ar.ar.com.au (8.9.1/8.9.1/AR-1.1) with SMTP id IAA20963
> > 	for <diy_efi at efi332.eng.ohio-state.edu>; Thu, 12 Nov 1998 08:20:10 +1100
> > Message-ID: <3649FD73.4ED7 at ar.com.au>
> > Date: Thu, 12 Nov 1998 08:11:15 +1100
> > From: Richard Wakeling <kojab at ar.com.au>
> > X-Mailer: Mozilla 3.0 (Win95; I)
> > MIME-Version: 1.0
> > To: diy_efi at efi332.eng.ohio-state.edu
> > Subject: Help needed reading Prom.
> > Content-Type: text/plain; charset=us-ascii
> > Content-Transfer-Encoding: 7bit
> 
> > Hi to you all,
> > 	I have come across a 28 pin prom that I just cant get a stable checksum
> > on. When I read it as a 27C128 I get FF in the bottom half of memory and
> > what looks like data in the top half. With the prom in its own circuit
> > pin 28 (VCC) is joined to pin 26 (A13) which would explain that they are
> > only looking for data in the top section of the prom and why the bottom
> > section is all FF. 
> > 	The prom data lines "D0" to "D7" going to the MC68hc11 are all
> > reversed, "D0 goes to "D7", D1" goes to "D6" etc. This of course will
> > give the incorrect hex readings when the prom is read but what is
> > causing the checksum to be different on every read attempt?
> > 	I have made sure all the pins are very clean as I know from experience
> > this can cause different checksums.
> > 	Any help would be gladly welcome.
> 
> > Thanks in advance
> > Cheers Richard.
>