I think it is just for the ignition timing. I am about to put an MSD, and an older style distributor in mine and someone told me after that I don't need the computer, but I really don't know.
The mid-80's 2.3L Mustangs had an electronic feedback carb, which was apparently used on vehicles by several different manufacturers around that time (for example, monte carlo's had electronic feedback Q-jets on them). That's probably what the "computer" you had was for. I'm pretty sure it just lets the computer control the timing, like hookamohog said.