Zilog Z80-MCB

While rooting around in some Z80 stuff today, I found a couple of Zilog boards, a little less than 8" square, with 62-pin edge connectors. One (the silk-screen says Z80-MCB) is obviously a processor+RAM+ROM+I/O board, and the other (the silk-screen says MDC2) some kind of RAM board. I'm looking for any other useful information. Here's what's on them: Z80-MCB: Z80, Z80-PIO, Z80-STC, AM9551, 4 empty 24-pin (ROM?) sockets, 8 x 446, a couple of small (MMI 6306) PROMs, assorted TTL, 4-way DIP switch, a 16-pin and an 8-pin socket with jumper blocks labelled "VDU", a pair of 16-pin sockets with unlabelled jumper blocks, 19.6608MHz crystal. In the top right corner there's a single-inline 7-way socket (looks like half of a 14-pin DIL socket). Two positions, J6 (8-pin) and J2 (16-pin) are empty. The MDC2 board has a Z80-PIO, 3 banks of 8 x 4116, what appear to be a couple of bipolar PROMs (one label is illegible, the other says "33-0053-16"), and assorted TTL. Both boards have a round red device that could be a voltage regulator on them. Any information gratefully received! -- Pete Peter Turnbull Dept. of Computer Science University of York