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World Moon Bounce Day 17th April 2010

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Apollo 11 videos

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Apollo Quotes

  • “I'd like to say I was smart enough to finish six grades in five years, but I think perhaps the teacher was just glad to get rid of me.”
    by Alan Shepard
  • “It's been a long way, but we're here.”
    by Alan Shepard
Apollo 13 40th Anniversary
Countdown to Launch:
2 months and 3 days
Safe splashdown:
2 months and 9 days
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Build your own Apollo Guidance Computer

Would you like to build the Guidance Computer Neil Armstrong used to land on the moon in 1969?

John Pultorak did just that! He created a working reproduction of the Apollo Guidance Computer (AGC). He then wrote a complete manual that allows you to build your own copy and released it on the Internet

apollo-agc-schematicJohn Pultorak, is a Lockheed Martin software engineer and at the age of 54, built his own Apollo Guidance system in his basement.It took him four years to build it  and he spent about $3, 000 for the hardware. If that wasn’t enough he then wrote  a massive 1,000 page long set of documents that includes detailed descriptions and all schematics needed for anyone to build their own unit.

He says: “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, and is the world’s first integrated circuit computer….. If you like, you can build one too. It will take you less time, and yours will be better than mine.”

He documented the project in 9 separate .pdf files:

  • Part 1 – Overview [8.1 MB]: Introduces the project.
  • Part 2 – CTL Module [9.9 MB]: Design and construction of the control module.
  • Part 3 – PROC Module [6.7 MB]: Design and construction of the processing (CPU) module.
  • Part 4 – MEM Module [6.8 MB]: Design and construction of the memory module.
  • Part 5 – IO Module [7.0 MB]: Design and construction of the display/keyboard (DSKY) module.
  • Part 6 – Assembler [0.5 MB]: A cross-assembler for AGC software development.
  • Part 7 – C++ Simulator [5.2 MB]: A low-level simulator that runs assembled AGC code.
  • Part 8 – Flight Software [2.8 MB]: My translation of portions of the COLOSSUS 249 flight software.
  • Part 9 – Test & Checkout [0.9 MB]: A suite of test programs in AGC assembly language.

    • apollo-agc-back-layoutWhy build an AGC?

    John Pultorak says: “Early computers are interesting. Because they’re simple, you can (if you like) actually understand the entire computer, from hardware to software. The AGC is the most interesting early computer because: a) it flew the first men to the moon; and b) it’s the world’s first integrated circuit (IC, or microchip) computer. It also has interesting architectural features.”

    This was state of the art at the time. It also gave a few people the scare of their lives when the LEM was starting its descent and the AGC display stopped processing data.

    The fault was sent to the backroom guys who quickly ascertained that it was just overloaded and would kick back in shortly and the mission was told to proceed. Luckily it did just that and Armstrong made his successful descent with one more heart stopping moment yet to come. It was the low fuel situation  caused by the craters and boulders in the path of where the LEM was trying to land. Armstrong took control and landed the LEM away from the rocks and craters.