WTB: Eprom Modules for the HP 75

[Sylvain Cote]

(10-04-2014 02:35 PM)Michael Fehlhammer Wrote:  I don't have a special eprom burner, but since I've read that CMT used standard eproms (27C256) I might be able to burn an eprom outside the module, using a standard eprom programmer.

Hello Michael

This link point to the CMT flyer for their EPROM modules
https://db.tt/UdfstGeg

The following pictures shows the CMT-75-32KE modules complete and taken apart
https://db.tt/KKisinJB
https://db.tt/rTW1HBjL
https://db.tt/yuNOnyVy
https://db.tt/0Z8PnzpW

This link point to the Microchip technical Reference Document for the 27C256 EPROM.
https://db.tt/WSVBPjUw

The CMT module uses the 27C256 EPROM with the PLCC package format directly soldered on the PCB.

Two solutions exist to reprogram the chip ...
1) unsoldered the chip from the board and put it into a an standard EPROM programmer with the PLCC adapter on it.
2) create a special PCB EPROM programmer adapter that map the connector and the three additional pins

In both case we also need to understand the PMS file structure to extract the 32K image needed for burning.
I have a PMS with the softwares and manual for it.

I have started 2 years ago a project to do the special PCB (option 2) and the extraction software, but never got around to finish it.
At some point I will finish that project, maybe in 2015.

Best regards,

Sylvain