This is a small program for DOS that takes a 4 digit hexadecimal number on the command line, splits it into two 2-digit numbers, and outputs each in turn to port 0x80 to display on a POST diagnostic card.
It is written in Borland C++.
One small caveat with these cards: it's impossible to display numbers where the first and second pairs of numbers are the same (for example 4242 or 6969) since it relies on a change of number to detect if a new POST status has been sent.