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CMT71-64E HP-71b eprom module questions - Printable Version

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CMT71-64E HP-71b eprom module questions - coitboy2000 - 06-05-2019 07:37 AM

Hi all

Does anyone have any experience opeining up these modules, removing the eprom and then erasing/writing new data to them ? I understand there is a purpose built eprom programmer that is very rare and therefore not an option. Another forum user has kindly offered to write them for me but I was trying to avoid burdening someone else, especially difficult given I am a half a world away in Australia.

I would love to know what these look like when pulled apart and what eprom is installed. Perhaps it could be desoldered and written with a newer usb eprom programmer?

Any comments appreciated

Cheers

Richard


RE: CMT71-64E HP-71b eprom module questions - Sylvain Cote - 06-05-2019 12:47 PM

Hello Richard,
Erasing them is the same as erasing any other EPROMs, you need an ultra-violet light box.
I alway used my CMT-71-P01 EPROM burner for these modules, if you change your mind I can also burn your data/programs to your EPROMs.
I have never reverse engineered this system (modules & burner) but like everything else, given time and effort it can be done.
Sylvain


RE: CMT71-64E HP-71b eprom module questions - coitboy2000 - 06-05-2019 01:10 PM

Thanks for the offer Sylvain. Much appreciated. I wasnt aware you has a programmer after trolling all the old relevant posts.

Can I ask what you have been able to flash onto the CMT eproms ? Are there any of the official rom modules that can't be placed on one of these 64k Eproms ? I guess it largely comes down to size ?

Richard


RE: CMT71-64E HP-71b eprom module questions - rprosperi - 06-05-2019 01:17 PM

(06-05-2019 01:10 PM)coitboy2000 Wrote:  Thanks for the offer Sylvain. Much appreciated. I wasnt aware you has a programmer after trolling all the old relevant posts.

Can I ask what you have been able to flash onto the CMT eproms ? Are there any of the official rom modules that can't be placed on one of these 64k Eproms ? I guess it largely comes down to size ?

Richard

All of the HP ROMs can be copied EXCEPT the FORTH/Assembler ROM and 41 Translator ROM, as they also include a hard-addressed ROM which requires additional module pins which are not available in the EPROM modules.

The burners are quite rare, but several of us have them and are willing to burn modules for fellow 71 addicts.

Regarding your original question about disassembling the modules, I'm sure someone has succeeded as some point, though I can't say for certain, but I have heard of more than one instance of modules being damaged in the attempt, so it may be best to have them burned, given the rarity and cost of the modules.


RE: CMT71-64E HP-71b eprom module questions - RamLab - 06-05-2019 02:19 PM

I did what you proposed, open the CMT 64K Module, desolder the 27C512 in PLCC 32, tried to read/program in a PLCC 32 Socket,
but that failed due to contact issues.
So I soldered it with wires to a DIL socket. I could read the EEprom,
Erase it, but re-programming failed, as did the second one. Since I could not easily get 27C512 chips, I bought a couple of
T1-74 Memory Modules...., and used their Atmel 27C512, and could program them. Soldered a PLCC 32 socket on the CMT module, put the Atmel in it,
and it did work !! The second one I did I continued to have contact problems,
so I soldered the Atmel direct to the CMT, it did work.
After some time, it failed, as did the one in the socket, if I do a CAT on the port, the Display turns blank.
In short, too much work for no result.

Peter


RE: CMT71-64E HP-71b eprom module questions - coitboy2000 - 06-05-2019 02:50 PM

Thanks Peter. I think you have convinced me its not a good idea.