Control Unit is broken

[AngriestIBM]

It says that you can use one of 8 inputs, yet when you wire the beast you get only 1-7 to choose from. (It should be 0-7)

Input 0 is the complement of RR.

The same goes for outputs - once you try wiring something out of the Control Unit you don't have a choice of what output you are using - you only get the default input

This is just how the mechanics system works. The output takes the form "PIN:VALUE" (like "2:1"), so you can filter that with OR gates (I think it was OR gates).

The two commands I failed to understand are IEN and OEN. They seem to be auxiliary registers. If so, do they serve any purpose (or are they just simple extra slots for holding information?)

IEN and OEN are Input ENable and Output ENable. The inputs are ANDed with IEN (So all inputs will read as zero if IEN is zero) and outputs only pass if OEN is true. I think this includes the internal memory, too.

This could be clarified in the information thingy that pops up when examining.

Ok.

http://en.wikipedia.org/wiki/Motorola_MC14500B

Thank you for your interest in esoteric spaceman nerd object.