Doug, spotted two errors on the lovely PCB layout:
(1) The trace to PAL U12 pin 3 isn't connected to anything - I assume it needs a green trace going vertically down to A1 on the PEB edge connector.
(2) I can't see how the ground trace running round the left / top / top-right of the board is connected to the ground trace at the bottom-right of the board. Is there a ground trace missing round the corner just below the floppy connector? Or maybe to the GND pins at the left end of the PEB connector?