MPLEX was an interesting project that I used to inspect integrated circuits and logic ports.
The project consisted of a LPT interface board, which was connected to the PC parallel port, and of a software running on QuickBasic.
The first version of the software was text based, but the second, release some months after, one was graphical.
Unfortunately, I found only the two versions of the software, but I cannot find the interface board schematic. Maybe I will find the board, in the future, and I will update this post with the pictures.
The MPLEX software, together with the interface, allowed to set and reset the pin of a logic port and read the output. It was also possible to load a sequence of logic levels and transmit it to the logic port.
Programming language: Microsoft QuickBasic.
Project started on: Aug, 1994. Status: just for personal use.