Bless you for trying to maintain old systems, as I have a soft spot for doing that. However, I question whether you are doing clients a favor, or not. Basing a lighting control
system on 30+ year old personal computers and throwing more money at it isn't a good idea . An Apple IIe is ripe for disk drive failures,
CRT failures,
power supply failures, and just plain failures. It makes more sense to update vintage
dimmer systems with
DMX to 0-10V converters, and going to a
console or a modern computer.