🚀 go-pugleaf

In article <2654@naucse.cse.nau.edu>, rrw@naucse.cse.nau.edu (Robert Wier) writes:
>  available EPROMs.  I've tried checking the IC Master, but
>  have drawn a blank there.  I wonder if anyone can come up
>  with a cross reference on the following:
> 
>         MMI 6336 (believe its 256 x 8)
>                 and now may be an AMD part
> 
>                 63S285 which is supposed to be equivalent
>                 to the 6336...
> 
>  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.

 Followup posting:

 I have found a couple of replacement parts.  Interestingly enough,
 there are 512 x 8 parts which are drop in replacements.  One of the
 pins on the 6336 was just permanently wired to logic 1 --- I suspect
 maybe these were 512 x 8 parts where 1/2 of the array was bad...

 Anyway, the "S" in the number seems to indicate a fusible link
 PROM.  We don't have anything to program those right offhand 
 (I did make a programmer once... seems like it was for an 82S23 -
 but I'm probably wrong on that.  Those puppys got HOT when you
 programmed 'em.  And of course, if you made a mistake, there 
 was NO going back :-)  )

 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.  On the other hand,
 there are BIG heatsinks on the other end of the board (I think
 it runs motors to turn the telescope).  It seems logical (sorry,
 couldn't resist :-)  ) that a fusible link PROM could deliver a 
 LOT more current than an equivalent CMOS part.  Is this right?

 Again, I'd GREATLY appreciate any suggestions on this...

 - Bob Wier

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