There is a PLD (Programmable Logic Device) on the computer board. Another blogger attempted to determine the gate configuration and posted the .jed file based on that study. Unfortunately, when I programmed a new PLC chip with that .jed file and installed it in the socket the unit was inoperable.  The OEM for the PLC used by amrel indicated that the device is rated for 20 years of data(configuration) retention. These instruments are now going on 30+ years.

The PPS-2322 OEM indicates that end of service life was 2015 (not bad for a mid 1990s product but doesn't help my efforts to backup the aging PLC.) 

If any readers have experience with PLC programming, please get in touch. I might try to figure this out.