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

Brent Hilpert hilpert at
Thu Jan 4 03:29:50 CST 2007

Allison wrote:
> Brent Hilpert <hilpert at>
> >
> >Chuck Guzis wrote:
> >> I stumbled on this document:
> >>
> >And whats up with this mention of LCD displays? I didn't think there was
> >anything practical available that early, or that was going to stand up to the
> >rigours of space-flight - I have a calc with one of the first commercial LCDs
> >(1972) and it's still kind of rudimentary - slow, poor contrast, temperature sensitive...
> My memory of LCDs is they were way too late for the AGC and the basic
> AGC design used either LEDs or Lamps in a 7 segment format.

Apparently it was electro-luminescent, see other messages (too early for LED
displays, too).

> >(And it confirmed that the AGC was constructed from a single gate/IC type.)
> That statement I believe is in error.  While the logic used was RTL and a
> single family type the logic elements for that family by the mid 60s were
> more diverse than just a two input NOR. My junkbox contains parts from

There are now two, perhaps three, sources from the period that indicate it was
a single gate/IC type: a dual 3-input NOR in 10-pin flat-pak. Read the
document Chuck ref'ed above (although there do seem to be some
mis-rememberings in there such as LCD instead of EL displays). I'm well aware
of the state of RTL/IC development at the time, but high-reliabiliy design
doesn't necessarily correlate with whats current in the rest of the industry.
Keep in mind the design started years before 1967/8. The IC spec sheets are
dated 1965.

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