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    Re: Neat video about LEM stellar alignment scope
    From: Don Seltzer
    Date: 2016 Jun 11, 19:25 -0400
    On Sat, Jun 11, 2016 at 4:48 PM, Francis Upchurch <NoReply_Upchurch@fer3.com> wrote:
    The  youtube video on the Apollo computer was an eye opener. It was pre-microchip, all small transistors wired by hand! 

    It is my understanding that the Apollo guidance computer was built with one of the first production digital logic microchips, manufactured by Fairchild.  It utilized Resistor-Transistor Logic (RTL), a fore-runner of the popular TTL families that were developed later.  The choice of circuit was frozen in the very early 1960's, based upon what was available, of known reliability, and could be produced in the needed volumes.  Only one type of logic circuit was used as the building block, a dual three input NOR gate in a ten pin flatpack.

    Don Seltzer
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