How To Build The 1MHz Apollo Guidance Computer For Just $US3000

$US3000. That's how much it costs to build the $US150,000 Apollo Guidance Computer today—the first computer to use integrated circuits, with a 1MHz clock, four 16-bits registers, 4K RAM, and 32K ROM—using 1960s-like components.

Designed by the MIT Instrumentation Laboratory and built by Raytheon, the Apollo Guiding Computer was the most advanced computer of its time. It ran a multitasking operating system called EXEC, capable of executing eight jobs simultaneously. What you are seeing above is just the visible part of it, the Dsky user interface, which was mounted in both the Command Module and the Lunar Module. The astronauts had to enter commands and data for the AGC to process using that keyboard, which also gave them feedback beyond the other million lights and indicators in the cockpits.

Back 40 years ago yesterday, the AGC ran into some unexpected problems: Executive overflows alarms fired up, caused by too many interrupts from the rendezvous radar. This radar was intentionally turned on by the astronauts in case there was a need to abort the mission fast. However, this data—coupled with the landing radar's stream—overloaded the AGC causing some commands to be delayed.

As we know Armstrong and Aldrin saved the day, helped by ground control and the programmers. The Eagle landed safely and they all lived happily ever after. If it were 1969, they would still be up there now.

You can try to build your own Apollo Guidance Computer following John Pultorak's full, and exhaustive and huge and dizzying, step-by-step instructions here. [Galaxiki via Universe Today—Image via ibiblio]

Check our complete Apollo 11 coverage here