So I’m slightly stumped on the Casablanca reverse engineering.

There’s four signals on the expansion bus that are generated by a single PAL.

This PAL uses the SIZ0, SIZ1 signals as well as A0 and A1 to generate the four signals.

There’s also another signal (DS?) from another CPLD on the board.

So… what could those four signals be? Something akin to UDS and LDS maybe?