Just chanced across something else that used the Molex socket.
https://www.ebay.com/itm/124169271006
The bag says Intermec and KIT,EPROM,9440,64K.
There is a company called Intermec that has the same Everett, WA address
as on that bag, and they have a device with a model number 9440.
I can't find any pictures of the back or inside, and the user manual
doesn't show anything either.
https://cybarcode.com/sites/cy/files/manuals/intermec/9440_irl_manual.pdf
But this spec sheet does say "Optional 32 KB or 64 KB EPROM cartridge"
in it:
https://cybarcode.com/sites/cy/files/specsheets/intermec/9440_specsheet.pdf
So besides Model 600 and Epson PX-4 and PX-8, that's one more thing that
used that socket.
--
bkw