Brief trace tracing:

DIP 40 DIP 8
-------------
pin 3 pin 3
pin 4 pin 2
pin 5 Pin 4

I think the DIP-14 and DIP-16 IO chips should give you a clue as to
the uC's port layout. I'm betting that one chip drives various
external relays while the other accepts inputs from sensors.

The DIP-16 does drive the relay coils.

One of them has Motorola logo, one National Semi. Other than that, the part
#s have been successfully rubbed off. A ghost of them remains, but an
electron-scanning microscope might be needed... (c;

Thanks.