Re: Using 28F256 in a 747 instead of 2732A??????????

["nacelp" <nacelp@bright.net>]

If the 28F256 is a pin for pin replacement for a 27256, then you have a
slight problem.  The 747 uses a 2732,  *24* pin, not a 28.
Grumpy



> Kevin Reynolds wrote:
> >
> > Shawn wrote,
> > If you remove the chip from the MEMCAL carrier, it might be easier to
> > swap in a 28F256 in its place to allow you to erase and write to it
> > without requiring UV.
> >
> > How does this work?
> > Do I then just plug this chip into the ECM without a "Holder"?
> > This would be great since I was just about to buy an eraser and now
could
> > put that money into chips.
> > Is there any draw backs/downside to doing this?
> > How is the 28F256 different? Size, storage amount, speed?
>
> Squash pretty much answered your questions, but I'll add that you
> probably need to solder the new chip into the MEMCAL carrier.  The
> original PROM is currently soldered in the MEMCAL carrier, but it is
> easily removed without much desoldering, in fact, a small flathead
> screwdriver can break the soldered connection in my experience and let
> you take out the old chip.  Then you can solder a 28F256 in its place.
> No drawbacks that I know of to doing it.
> The 28F256 is a Flash version of the 27C256.  It has the same number of
> pins and same pinout except it is usually made of plastic and has no
> window (EPROMs are usually made of gray ceramic and have a window).
> Same storage amount, I think speed is similar or very close.  Then all
> you need to do is make an adapter so you can connect the entire MEMCAL
> to your programmer and erase/write to it as much as you want.
> No downsides to doing this that I'm aware of, but I personally haven't
> done it (yet).
>
> My programmer is PC based and has Erase as a menu option.  That blanks
> out the whole chip and makes it ready for programming.  It's pretty easy
> to do.  I used to make a few dollars several years ago programming Flash
> ROM chips for people that accidentally screwed them up when trying to
> upgrade the BIOS on their PCs.
>
> Shawn
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