NASA Office of Logic Design

A scientific study of the problems of digital engineering for space flight systems,
with a view to their practical solution.

Apollo Guidance Computer

Block 2 Parts Analysis

Apollo Guidance Computer Logic Study

A study is underway to research the quality and long term reliability of logic¹ used for the Apollo Guidance Computer (AGC), which was designed by MIT's Instrumentation Laboratory. There were two versions of this computer built. Block I and Block II². Block I units used, as a logic element, a single 3-input NOR function, with V_CC = 3V, packaged in a TO-47 can. Block II microcircuits, packaged in flat packs as shown in the image below, were dual 3-input NOR functions, with V_CC = 4V. Both types of circuits, which use RTL, had a fanout of six.

It is planned to report progress of this study here and then formally publish the results.

Block 2 Microcircuits
in flat packs

Equivalent circuit for a Micrologic gate

The circuit operates as follows.  When any of the inputs is a logic '1', then the npn transistor is driven into saturation, clamping the output at a logic '0'.  If all of the inputs are logic '0's, then all transistors are cutoff and the pullup resistor drives the output to a logic '1'. 

Digital Logic and Computer Design
M. Morris Mano
Prentice-Hall, Inc., ©1979
pp. 562-563

For a summary of older logic technologies: Old_Logic.htm

Related Pages:

1. AGC NOR Gate Specifications
2. AGC Integrated Circuit Packages
3. AGC Integrated Circuits and Reliability Page.

X-RAY Analysis

S/N H08423

S/N H09263

PIND Testing

Both of our samples passed PIND testing to MIL-STD-883E, Method 2020