PROM Size on a 165

[Craig Marcho]

well, I know I had a '165 chip for an '87 vette that was supposed to be 128,
and had a 256 chip on it. Funny thing was, the low side of the chip was
blank, and the high side was programmed. This was a Delco original chip,
too.... so I think to be safe, program both sides.

Craig M.


----- Original Message -----
From: <ae2598 at wayne.edu>
To: <gmecm at diy-efi.org>
Sent: Friday, November 17, 2000 7:42 AM
Subject: Re: PROM Size on a 165


> Is double-loading the thing to do, instead of just blanking out the second
> half?  I ran into the same situation at work, I took an image off a 128 to
> replicate, but only had 256's to use for the copies.  Nobody around here
> had 'em in stock, either.. 128 must've been an unpopular size?  Anyway I
> took the 128 image, only write the first 1/2 of the chip, leaving the high
> side blank, and it seemed to work.  I guess the success of this would
> depend on what the 128 circuit does with the pin that is used as the
> high-order address line on the 256, I can't remember if it was NC or if it
> had some other use on the 128.
>
>  On Thu, 16 Nov 2000, Bruce Plecan wrote:
>
> >
> > Double load the 128 image in the 256 and be done with it (er go for it)
> > Bruce
> >
> >
> >
> > > Newbie working on a 165 ECM.  I have many 256 PROM's but no 128's.
I'd
> > like
> > > to put the 256's to work.  The schematic's I have seen on ECMGUY's
site,
> > > show what looks like PROM pin 27 wired to A14 of the ECM bus.  (CS and
OE
> > > are also reversed)  This does not make sense.  Pin 27 of the original
128
> > > PROM is /pgm pin, which should be tied high in the ECM.
> > >
> > > I'm guessing the schematic was made from a later version ECM that
takes
> > 256
> > > PROM's.  (Hense the A14 connection.)
> > >
> > > Does the MEMCAL not interface w/ A14 on the ECM board?  i.e. Does the
> > MEMCAL
> > > tie PROM pin 27 high?  Can someone confirm that PROM pin 27 on a 165
ECM
> > is
> > > held high all the time?  Will using a 256 part for a 128 ECM cause
error
> > > conditions for certain BIN editors?  i.e. Do the editors check this?
> > >
> > > I apologies if this has been discussed before, I have not yet found
the
> > > archive seach.
> > >
> > > ML
> > >
> > >
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