The Williams cpu test board was connected to the Address and data bus to check for any locked lines.
at the time system 7 did not exist and not mentioned in the test fixture manual however the cpu tester will run tests on it.

CPU tester (1) (resized).jpg

CPU tester (2) (resized).jpg

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That's what I was looking for, do you have a clear schematic of it? The online download I found was a little hard to read. It mentions some sort of adapter or seperate unit to test the two different styles of microprocessors.

This is it, complete. there is no other adaptor and the Cpu tester Bypasses the microprocessor and is not used except for connection to the address and data busses
In Theory the adaptor clip piggy backs on the microprocessor to tap the Address and Data lines the cpu tester wired to connect on the system 3-4 6800 processor pin outs.
the manual instructs to place a 6800 on a system 6 so that several test lines aren't blocked with a 6802 or 6808 in place as their pinouts are arranged slightly different.

The cpu tester does not need a microprocessor installed and can be connected to the microprocessor socket without any microprocessor in the socket with modification to allow the test clip to attach.

The cpu tester runs on its built in timer circuits to pull the address and data lines high and low.

Cpu tester instructions:
https://www.pinwiki.com/wiki/images/a/a7/Williams-test-fixture-sys3-7-manual.pdf starting on pg 39

Tester checks 5 other lines depending which ver cpu is under test There are 5 leds additional for Blanking, NMI, 02,and Reset and a toggle to put the R/W line H or L to perform 2 tests on the busses while Add and Data lines in either state