Tested on a pi400.
Inspired by https://www.instructables.com/Raspberry-Pi-Python-EEPROM-Programmer/
See https://hackaday.io/project/182779-late-90s-gps-time-unit-repair-1024-week-bug-fix/log/201888-reverse-engineering-first-steps for context
Rough diagram of pinout:
Note that pins 3&5 have hard wired pullup resistors and thus have to be used for CE# and OE# pins only.
Photo of quick and dirty circuit on connected to Pi400:
Added CC license because the original article on instructables was also CC
The eprom.sh was a experiment to do the same thing using bash. It works, but very very very very slowly (e.g. takes over 10 hours to read!) Also I had a bug with the data lines backwards at one point, so the flip.py program was used to fixup the image file.