Originally Posted By hap
Seems it's same as tntell:
// R10: TMS5100 PDC pin
// R9: power-off request, on falling edge
// R0-R8: input mux

// K: multiplexed inputs
// K4: TMS5100 CTL1

// O3210: TMS5100 CTL8124
I see O4 and O5 on the output PLA too, they're not connected?

Yep, that's correct. O4 and O5 go to some unpopulated traces. There are places for 5 resistors/diodes that would have connected K4 and K8 with O4 and O5. But as it is, they are NC.