The Apollo Guidance Computer Architecture and Operation Frank O’Brien Infoage Science/History Learning Center Infoage Science/History Learning Center The Apollo Guidance Computer: Architecture and Operation What we hope to accomplish • Lunar Mission Profile • AGC Requirements • AGC Evolution (very short) • Hardware overview • Software overview • User interface • “How to land on the Moon”! Infoage Science/History Learning Center The Apollo Guidance Computer: Architecture and Operation Command and Service Modules Infoage Science/History Learning Center The Apollo Guidance Computer: Architecture and Operation Lunar Module Infoage Science/History Learning Center The Apollo Guidance Computer: Architecture and Operation Lunar Mission Profile Infoage Science/History Learning Center The Apollo Guidance Computer: Architecture and Operation AGC Origins • MIT Instrumentation Lab – Now Charles Stark Draper Laboratory • Early work done on Polaris ballistic missile • NASA contracted MIT to create AGC • Vigorous debate on the interaction of man, spacecraft and computer • As Apollo requirements grew, computer requirement grew even more! Infoage Science/History Learning Center The Apollo Guidance Computer: Architecture and Operation Early Design Issues • What systems will it interface with? • How much computing capacity? • What type of circuit technology? • Reliability and/or in-flight maintenance? • What do we *need* a computer to do? • What does a human interface look like? Infoage Science/History Learning Center The Apollo Guidance Computer: Architecture and Operation AGC Evolution • Origins were with the Polaris SLBM • AGC went through several iterations: – Packaging improvements – Faster logic – Circuitry changed dramatically • Core-transitor logic • “Gate-on-a-chip” (in a “can”) • “Micrologic” two gates on a flat-pack “chip” – More complex instruction set – Increases in memory (both ROM and RAM) – In-flight maintenance requirement dropped Infoage Science/History Learning Center The Apollo Guidance Computer: Architecture and Operation Logic Chips • Fairchild introduced the “Micrologic” chip • Two triple-input NOR gates per chip • Resistor-Transistor Logic • Virtually all logic implemented using the Micrologic chips – Single component greatly simplifies design, testing – Greater production quantities -> better yields and higher quality – Several hundred thousand chips procured (!) Infoage Science/History Learning Center The Apollo Guidance Computer: Architecture and Operation Micrologic chips installed on “Logic Stick” Infoage Science/History Learning Center