Vacuum tube systems in apollo era space missions

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.

• if you google "apollo flight computer" you can get detailed plans, schematics even. – JustJeff May 25 '11 at 19:10
• 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. – Olin Lathrop Sep 2 '12 at 12:57

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.

• glad you found that, i knew it was out there, just couldn't dredge it up. – JustJeff May 26 '11 at 10:35
• btw, you might want to indent the abstract, make it be a different font, or at least throw quotation marks around it. – JustJeff May 26 '11 at 10:36
• JustJeff, I knew exactly where to find that page: in my "TO DO" bookmarks :-) (You're right... I've put blockquotes around abstract) – Axeman May 26 '11 at 12:50

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.

• Apollo guidance computer was one of the first to use ICs Interesting. I didn't know that. I'll have to look that up. – Falmarri May 25 '11 at 22:50
• 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. – gbarry Sep 2 '12 at 5:12
• 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. – Chris Stratton Sep 3 '12 at 12:36

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."


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.

• 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. – Axeman Sep 2 '12 at 9:58