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How to read/write older 23xx/25xx series EPROMS?

O

oktology

Experienced Member
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Mar 24, 2023
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Houston TX
Trying to burn JiffyDOS for my SX64, and I happen to have some Motorola MCM68766en, AKA TMS2564. Unfortunately, no PROMS with this pinout are supported by my T48 programmer.

Is there another tool or programmer I can use with a modern machine, or am I going to have to figure out some Windows-95-based Rube Goldberg situation?
 
In 1991 I received a programmer from a shop for free because the manual and software were missing. It was all plain TTL so I re-engineered it and wrote my own program in Turbo Pascal. About 25 years ago I ran into the same situation and the newer programmer I had at that time didn't know this EPROM either. So I dug up the old programmer and all I had to do was to add a bunch of parameters.
Later I bought the Elnec LabProg+ and it could handle this EPROM.

But to help you: please look at this site. Title:

An easy to build programmer for 2704 / 2708 / TMS2716 / MCM68764 / MCM68766 EPROMs​

I hope this helps :)
 
The only other option is to make an adapter for your T48 programmer. But this is still fraught with problems because you have to ensure that the correct programming voltage and programming algorithm is used by selecting the corresponding device type on the T48. Some of the T48 settings do not work as advertised either...

As Larry says, the easiest option is to pay someone for postage (and a beer) and send them the device and file...

The T48 is cheap - but comes with limitations...

Dave
 
daver2 said:
The only other option is to make an adapter for your T48 programmer. But this is still fraught with problems because you have to ensure that the correct programming voltage and programming algorithm is used by selecting the corresponding device type on the T48.
Click to expand...
The only issue other than pinout, I think, is programming voltage, which XGecu lets you set manually.
 
Sure, I was just saying that programming algorithm is likely to not be tremendously different between a 27xx NMOS device and a 23xx/25xx [I can't tell that there's any difference between the two nomenclatures] NMOS device.

Having other people program chips for me sort of defeats the purpose. If I'm going to have to wait for something to arrive, I would just buy one of the modern-production pin-compatible modules. Sometimes I want to get the thing done right now, ya know?
 
Ruud said:
That is how it is done on the C64 and VIC-20. A quick search on Ebay gave me this adapter.
Click to expand...
Yes, the Datamaster employs Mostek MK36000 and some Motorola EPROMs, which are pin-compatible with the MOS 2364 (CS low). So we employ these kind of adapters.

It doesn't look retro, but I expect this solution to be one of the longest-lived around.
 
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