back to the AGC, was Re: TTL 7400's Available

Gordon JC Pearce wrote: I'm not surprised that some basic use of the technology was around at the time, so no it's not a huge stretch in principle. However, for such an item as a numeric display I anticipated NASA would be going with something with a track record as opposed to a special development. I expect there are lot of little incandescent indicators in the capsule and standardising on one bulb type (hence one set of spares) would have benefits. Plus, while EL may have the benefit of low power consumption, it does require a special power supply and driver requirements. One of the AGC writeups indicates they got around the latter by using relays (later SCRs, I think it said) to drive the segments. I guess they felt that the basic EL principle was reliable enough that they were comfortable developing with it. Or perhaps those displays were a very high-end (military) thing and I just don't/didn't get to see equipment that may have used it. I do have one multi-digit (what I believe to be) EL display from 1973 (not Gas-Discharge, not VF, not LCD, not LED), sans equipment. Have to try lighting it up someday.