In my last post I showed the buffer board that was in the main unit. The board connected to the interface pod with a long cable which connected to another buffer board in the pod.
The board is composed mainly of bus driver ICs and DIP resistor packs. There are also PAL (Programmable Array Logic) chips. The connectors on the left appear to be for external trigger signals that the system can monitor and react to.
On the back of the board the three blue connectors connect to the other board in the pod, and there for connectors on the left are for the cable to the main unit. There is also two pin connector at the bottom the brings power to the pod.
The most interesting thing about this board is that it is the only surface mount board in the system, everything else is through-hole. I did notice that the chips on the other boards had date codes from the late 80’s up until 1990, but this board has date codes of 1994 and 95. I guess it’s possible this board was originally done as through-hole but at some point in the life of the unit it got replaced with newer board which was surface mount.