I am toying around with some of Hans' single rom adapters on some of these boards.

I have an interesting question...

The hardware should work like this:

6800 -> System 4: YES
6808 -> System 4: YES (?????????? The golden question!)
6800 -> System 6: NO WAY
6808 -> System 6: YES

While I have figured out I cannot downgrade, what about upgrade? A 6800 will not work in place of a 6808 because it lacks a clock circuit in its chip and the external clock circuit was removed actually as an UPGRADE from Williams system 6 boards in expectance of a 6808. Using a 6800 on a board designed for a 6808 (which came with an internal clock signal, new feature at the time) will not give any clock signal as the 6800 lacks the ability to make one, and the external circuit was removed since the new chip did it for them - this would give ZERO clock signals. Using a 6800 on a board with an external clock circuit, or a 6808 on a board without one, properly gives 1 clock signal. But what happens if you use a 6808 on a board designed for a 6800 that also has an external clock signal - meaning there are two clock signals, now one internal, one external?

When pairing CPUs with these boards, MUST I use a 6800 on a System 4, or will a 6808 ignore the external clock circuit and use its own? This is a gray area.

Please note I am not asking to replace a 6808 with a 6800. The external clock circuit was removed after System 4 so this will definitely not work. Read my question carefully. It's an interesting one.

We are overexceeding the amount of clock signals, 0 is no good, 1 is perfect, but 2... what happens?

Thanks!