Lunar Lander Bipolar PROM vs EPROM question?

Jeff F

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Working on a Lunar Lander PCB and read that you can replace the sixteen bipolar PROMs with four 2716 EPROMs. Since I've already found two bad bipolar PROM sockets I'd like to do this but just wanted to check here first.

Seems like it makes sense but I just want to make sure there isn't anything else required when doing the swap.

So, has anybody here done this swap successfully?

I have to dig out my Needhams PB10 computer so I'll probably do this after lunch.

Thanks in advance, :beerchug:
Jeff
 
EPROMs are typically not fast enough to replace bipolar PROMs, but maybe it'll work for LL if you can find a fast 2716. You might have better luck finding a fast 2732 instead. I've used Simtek NVRAMs before, as they are very fast (45ns).
 
Matt's advice is good, and applicable to replacing bipolar PROMs with EPROMs in general.

However, specifically regarding Lunar Lander... I'm 90%+ certain that the -02 PCBs were shipped from the factory with EPROMs instead of PROMs the -01 had. So, I'm pretty sure the speed isn't going to be a big issue in this case.
 
Just wanted to verify this works.
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From the manual in the test mode/troubleshooting section...

-01 has 16 bipolar PROMs
-01 alternate has 8 bipolor PROMs
-02 has 4 EPROMs
From the readme.txt file in the ROM package at AndysArcade.De...
Some boards may use bipolar PROMs instead of EPROMs. It is
easiest to simply replace the PROMs with EPROMs if the EPROM
sockets are loaded.
So I think it's probably what DarrenF said that in the case of Lunar Lander it's doable. Where Matt is probably right for the other 99% of the time. :)

Thanks guys for all the input. Believe it or not I started this 5 or 6 hours ago but 1st had problems with the recycled EPROMs and then ran into a dead 6502 processor. Made this whole thing just soooo much fun. :D

Thanks again. :beerchug:
 
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