Path: utzoo!attcan!uunet!pilchuck!ssc!markz
From: markz@ssc.UUCP (Mark Zenier)
Newsgroups: sci.electronics
Subject: Re: PROM <-> EPROM cross ref?
Message-ID: <379@ssc.UUCP>
Date: 13 Oct 90 21:21:02 GMT
References: <2654@naucse.cse.nau.edu> <2668@naucse.cse.nau.edu>
Organization: SSC, Inc., Seattle, WA
Lines: 40

In article <2668@naucse.cse.nau.edu>, rrw@naucse.cse.nau.edu (Robert Wier) writes:
> > I wonder if anyone can come up
> >  with a cross reference on the following:
> >         MMI 6336 (believe its 256 x 8)
> >                 63S285 which is supposed to be equivalent
> > 
> >  I'd GREATLY appreciate any help in getting a cross reference to
> >  a EPROM (if one exists...) that would be a drop in replacement
> >  for the PROM.
> 
>  .  We don't have anything to program those right offhand 
> 
>  Question: the spec sheets tend to indicate a TTL level, Tri
>  State device.  Assuming we could find a configuration with a
>  compatible pin out in a CMOS UVeraseable device, would it be
>  drop - in compatible?  Or would we have to look at the 
>  schematic to be sure (don't have it right handy).  I'm aware
>  the "S" part is going to be much faster than a CMOS part, but
>  in this application speed doesn't seem critical.  

>  couldn't resist :-)  ) that a fusible link PROM could deliver a 
>  LOT more current than an equivalent CMOS part.  Is this right?

(Well, my Email died)


A quick databook search came up with the Cypress CY7C281 or CY7C282.
They're 1k by 8, with the 4 chip enables.  Pins 22 and 23 are
not used on the 63s285, and are addresses on the cypress parts.
It has the same output capablities.

Getting one programmed may be just as difficult as getting
the original part duplicated.

With the 4 chip enables, and the 16 mA per pin, you'd need a
daughter board with a couple of extra chips if you wanted to
use a 27xx part.

Mark Zenier
markz@ssc.uucp