Finally got clear enough of TRS-80 projects to spend some time getting this board going.
The boards were made in NZ and sold as a "controller" but also as a basis for a complete Z80 machine with a disk controller.
I don't know the history of this board. There are hand written comments on the documentation about "Pye TV's" and "Sheraton Rotorua" and I had an email discussion with Mark Eaton at Compuspec (the manufacturer still exists) and he said some of these boards were used to drive information screens in hotels.
I only have the main PCB which had been burgled for a few parts but thanks to the documentation it was actually pretty easy to get going.
Needed a replacement 4.9152 mhz xtal for the STC (AM9513 System Timing Controller). This is used for the real time clock but more importantly the clock for the SIO (Z80 SIO/0 serial IO controller). Also a clean up around the reset circuit. Looks like a reset switch or something was removed so the board by someone with a plumbers soldering iron so it wasn't in great shape there. The serial level converters needed to be replaced (MC1488 and MC1489) although they may never have been fitted because the CTS pullup resistors were not fitted to the board (more on that below).
It took some digging into the ROM to work out why the CPU seemed to run and the STC was configured to generate the correct SIO clock frequency but nothing appeared in the terminal.
Two things.... the console is actually on port B of the SIO (not directly stated in the documentation although implied by the pinout on the serial header).
Also because the CTS pullup resistors were not fitted. These pull the CTS lines at the serial connector to +12V which is inverted by the MC1489 to be "active low" for the SIO /CTSA and /CTSB signals. Without the resistors these signals are +5V and the SIO won't transmit anything.
So it works. Monitor ROM and Tiny Basic both run and work as documented.
Really nice little board and a real piece of NZ computing history. I have scanned the documentation so will post it on my blog should anyone else come across a Compuspec board and want to get it going.