rrw@naucse.cse.nau.edu (Robert Wier) (10/10/90)
The campus observatory here has asked for help with the
following problem:
Due to a close lightning strike, a number of pieces of equipment
were zapped (telescope guidance, etc). Things have been put
back together except for a PROM which is suspect. There are
two other similar PROM sets can be compared against, IF we
can get parameters on how to read it. We have an EPROM programmer
which could possibly be used to read the old PROM and program
a new EPROM. However, other than the pin out, we don't have
a clue as to compatibility between the old PROM and currently
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.
THANKS!
- Bob Wier
-------------- insert favorite standard disclaimers here ----------
College of Engineering
Northern Arizona University / Flagstaff, Arizona
Internet: rrw@naucse.cse.nau.edu | BITNET: WIER@NAUVAX | WB5KXH
or uucp: ...arizona!naucse!rrw
rrw@naucse.cse.nau.edu (Robert Wier) (10/11/90)
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 -------------- insert favorite standard disclaimers here ---------- College of Engineering Northern Arizona University / Flagstaff, Arizona Internet: rrw@naucse.cse.nau.edu | BITNET: WIER@NAUVAX | WB5KXH or uucp: ...arizona!naucse!rrw
markz@ssc.UUCP (Mark Zenier) (10/14/90)
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