So neither the GAL nor the 74ACT86 do anything on that SE/30 adapter if you use it in the SE/30...
The GAL code is the same as on the Daystar IIsi only adapter.
The input signals present at the GAL are the same as on the IIsi adapter, only a few output pins are routed to different places on the SE/30 connector.
Only signals that are important are on pins 17, 18 and 19.
/CFLUSH stays high all the time. Pin 18 (connected to C20 on the SE/30 cache connector) is high all the time as well.
/CENABLE stays low all the time.
The 74*86 outputs a high signal all the time as well because the two inputs 1 and 2 are receiving the same signal. CPUCLK and C16M are tied together on the SE/30 PDS slot.
It will only output something on the IIsi where CPUCLK is 20MHz and C16M is - guess what :tongue: - 16MHz. The signal coming out of there is then routed to /CFLUSH on the IIsi cache connector.
This means for a P33 -> SE/30 only adapter there isn't any GAL (or even any chip) needed at all. A 7486 to boost the clock signal if you use two PDS cards would be a good thing to do though as this constellation might cause problems otherwise.
If you wanted you could even wire up your P33 to the SE/30 PDS using a lot of jumper wires. No magic going on here at all.