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I hope this is the right place to ask this. But my friend is just learning about electronics and just was given an old vacuum tube. Just because I'm curious, is there any technical information on the computer systems used for the Apollo space missions? (Not a system diagram, just an overall summary). Specifically, I was just curious as to the number of vacuum tubes used in both the apollo spacecraft as well as the mission control computers.

I'd just like a high level description if possible. I'm an EE grad but I'm explaining transistors and digital electronic systems to my friend who's not an engineer, but is a bio researcher.

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  • \$\begingroup\$ if you google "apollo flight computer" you can get detailed plans, schematics even. \$\endgroup\$
    – JustJeff
    May 25, 2011 at 19:10
  • \$\begingroup\$ I really don't think the apollo computer used vaccuum tubes. The size, weight, and power requirements for space flight hardware would have made transistors much much more attractive, even if they cost many times what a vaccuum tube did. \$\endgroup\$ Sep 2, 2012 at 12:57

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The only place where valves were used might have been in the final stages of the various transmitters and radars. The spacecraft and mission control computers would have been solid-state systems; the Apollo guidance computer was one of the first to use ICs. Mainframe computers at the time used transistors, I worked for a company that built them.

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  • \$\begingroup\$ Apollo guidance computer was one of the first to use ICs Interesting. I didn't know that. I'll have to look that up. \$\endgroup\$
    – Falmarri
    May 25, 2011 at 22:50
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    \$\begingroup\$ A lot of development effort went into integrated circuits on behalf of the space program, an effort which transformed them from lab curiosity to practical components. \$\endgroup\$
    – gbarry
    Sep 2, 2012 at 5:12
  • \$\begingroup\$ Part of what they did was use few (possibly just one) ICs in large quantity, allowing a focus on production yield. The design was mostly NOR gates, which like NAND are a universal logic element from which everything else can be constructed. \$\endgroup\$ Sep 3, 2012 at 12:36
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Start from this page and drool :-)

http://klabs.org/history/build_agc/

Abstract of the page:

This report describes my successful project to build a working reproduction of the 1964 prototype for the Block I Apollo Guidance Computer. The AGC is the flight computer for the Apollo moon landings, with one unit in the command module and one in the LEM.

I built it in my basement. It took me 4 years.

If you like, you can build one too. It will take you less time, and yours will be better than mine.

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  • \$\begingroup\$ glad you found that, i knew it was out there, just couldn't dredge it up. \$\endgroup\$
    – JustJeff
    May 26, 2011 at 10:35
  • \$\begingroup\$ btw, you might want to indent the abstract, make it be a different font, or at least throw quotation marks around it. \$\endgroup\$
    – JustJeff
    May 26, 2011 at 10:36
  • \$\begingroup\$ JustJeff, I knew exactly where to find that page: in my "TO DO" bookmarks :-) (You're right... I've put blockquotes around abstract) \$\endgroup\$
    – Axeman
    May 26, 2011 at 12:50
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I am Ed Uber and led a line of up to 29 women who built the S10 boards for the Apollo spacecrafts and prior to becoming a leadman, built many of these wire harnesses inn La Mirada, CA, for North American Aviation who became North American Rockwell.

A new facility called Autonetics was built in Anaheim, CA. Here is where we built the Apollo computers. These women did a fantastic job. Although we did not regularly install the 9 Raytheon tubes, we did on several occasions. We were to build 110 for onboard and testing. We ran out of tubes on #101 and they would not order a new set since a minimum amount on the order was required and they were so expensive. There were so few failures, they did not build the last 9 computers. The processor on our boards was several IC's, but no processor chip.

I am not sure what our computers did on board the Apollo, but there were 5 according to the information given us.

I personally have a letter signed by all of the Astronauts thanking me for our work on these computers. Therefore I find it hard to believe that our tube computers were not on board. They had 8 tubes and a parity tube.

The women who worked for me were fantastic and did a marvelous job. On the first 4 computers they functionally tested each of the boards individually without a single failure, so after that they put the computers together and only ran the final tests on the complete computers. There were only minor failures until #58. None of these failures were due to anything built by my women. Number 58 went up in smoke. The reason for this was an Engineering Order shorting +12Volt, +5Volt, and Ground. These women worked for me for almost 10 years and that was the only major failure. Most 0f the problems were with the ground going to the wrong bombtail coming down on an EO.

I was not an engineer at that time, and I only know what we built, and what they told us at Autonetics.

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Not sure it did use vacuum tubes. Maybe the soviets used them? Anyway, according to this site,

"The Apollo Guidance Computer (AGC) was built by Raytheon and used 
approximately 4000 discrete integrated circuits from Fairchild Semiconductor."
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A cathode ray tube is a vacuum tube, so, anywhere there was a display screen, there would have been a CRT. I also suspect any video cameras they used had imaging tubes in them.

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    \$\begingroup\$ Apollo Guidance Computers never had CRT displays. There were just seven 7-segments electroluminescent displays for program number, verb/noun commands, and 3 registers. Another 10-15 indicators (electroluminescent too) were for alerts. You're right for the video cameras used to broadcast video signals to earth, that had vidicon tubes inside, and for the CRTs in the control rooms. \$\endgroup\$
    – Axeman
    Sep 2, 2012 at 9:58

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