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Very cool project! "I am quite desperately looking for an EPROM programmer capable of reading and writing 2708 type EPROMs since I am afraid that the 2708 EPRO
by smoyer 10y ago
Very cool project!
"I am quite desperately looking for an EPROM programmer capable of reading and writing 2708 type EPROMs since I am afraid that the 2708 EPROMs on this board will loose their contents - the are already about 20 years old."
It's not very hard to build your own programmer/verifier (reader) ... if you can't find schematics then message me. But this is very important. Those EPROMs are are erased by shining UV light through the window in the package ... get some UV opaque material over those windows immediately and stop leaving them in the light.
In the mean-time, I'll dig around in my basement and see if I still have the correct programmer for that part (I vaguely remember using it to restore my COSMAC ELF to operation).
- alexandrerond 10y agoit's from 2005...
- convolvatron 10y agoa reader would be easy from a micro controller with 20 lines of code....the writer part with the weird voltage and uv regimens you can wait one until you need to make a copy i don't know if there is a 2708, but there were some eprom functionally compatible replacements that used more modern technology
- kwhitefoot 10y agoI used to use 2708 and 2716 EPROMS for 6502 embedded controller work in the early 80s. The programmer was just a couple of buffers and a half a dozen discrete components plugged in to an Apple II. Unfortunately I don't have the circuit but it was a trivial thing to put together and was printed in one of the many hardware magazines of the time, perhaps someone else remembers it. It should be pretty easy to do now with an Arduino or similar. The only odd thing you need is a relatively high voltage for the actual write (it's a long time ago but I seem to remember 30V).