Diagnostic code for Oberheim OB-X Synthesizer

I was recently contacted by someone looking for a copy of the Oberheim Diagnostic firmware for the OB-X. I have never worked on an OB-X and did not have this code, but decided to see if I could make something similar. The person who had contacted me was able to program 2708 EPROMs, and was able to test the different versions of the program and suggest improvements. (We eventually determined that one of the 2708 firmware EPROMs in the OB-X that he was repairing had started to lose its data. Fixing that got the synth working again)

The new diagnostic firmware has the following tests:

1) 256-byte scratchpad memory test

2) Program RAM test (erases any programs)

3) DAC ramp/gates toggle test

4) Panel LEDs test

5) EPROM checksum test

6) Panel switches test

7) Control voltages sample and hold test

The test firmware is offered on as-is basis:

The test firmware has only been tested by one person, in one OB-X. I cannot guarantee that it will run properly in every OB-X.

Here are the files:

Here is an archive containing a 1K binary image of the test code and the instructions for running the tests. If your OB-X has been modified to use a single 2732, simply place this image in the bottom 1K of the EPROM, and place some data with known checksums in the second and third 1K blocks of the EPROM. This will be useful for the EPROM checksum test.