μblog: engineering from the trenches

I recently inherited a pair of wire-wrapped boards full of 74AS series logic that were of unknown origin and unknown function. I was told to either take them home or throw them out, so I took the chips home and threw the boards out. Now comes the question: what to do with all of these chips? As there are applications where using positive feedback is advantageous, sometimes its good to have race conditions. I’m thinking of designing a circuit to roll a die whose number is generated through the exploitation of race conditions. The easiest method to do this would be to create a feedback circuit that runs while a button is held down whose iterations are not very predictable. The second method is to implement a state machine with enough state variables to try to guarantee that multiple bits are changed in the state variable at every transition and try to develop a non-deterministic state change order. If these two methods don’t work well, I can try to operate the logic in the gray area, although I think that the threshold for high or low is a manufacturing parameter and is fairly fixed. More on this after I try this out in the lab next week.

del.icio.us | digg