The Boxcar RS232 peripheral was produced by Microdistributors and gave the user a parallel and an RS232 interface which plugged into the expansion slot on the console. With this device you didn't need a PEB have these interfaces.

This picture shows the front of the box and the expansion port on the side. It also came with a velcro strip to make sure that it kept it's connection. This device had to be installed next to the console. You could then connect other devices to it.

This pictures shows the RS232 connection, the parallel port, and the hookup for the 5 volt power supply.

Here is the circuit board.