NASA Office of Logic Design

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.

Lunar Module Interface Control Drawings

Documentation Courtesy of Eldon Hall, MIT Instrumentation Laboratory


Introduction (excerpt)

This ICD defines and unless otherwise stated, controls the electrical signal interface between the LM Guidance Computer (LGC), including the DSKY, and LM Spacecraft subsystems. Electrical requirements for the interface through which spacecraft prime power is supplied to the LGC are included for reference only. The controlling document for prime power is LIS-390-10002.

This ICD is divided into sixteen sub-sections. Each sub-section defines particular LGC-LM interfaces with respect to the following:

  1. Signal nomenclature

  2. Signal/connector/pin assignments

  3. Source and load impedance

  4. Signal characteristics

  5. Interface circuitry

  6. Functional Description

The noise limits referred to for a given interface circuit are those which could be attained without affecting the proper functioning of the interface. As a general rule, however, the interference emanating from either side of the interface shall not exceed the limits specified in MIL-I-26600/MSC-EMI-10A. The susceptibility of the respective equipments on either side of the interface shall meet the requirements of the same specifications.

The nomenclature used in describing the pulse signal characteristics is defined in appendix A (Sheet 110).

For the purpose of this ICD, a logic "1" denotes that the function or condition specified by the signal nomenclature is being performed. i.e.: A logic "1" for the Auto Angle Track Enable means that the Auto Angle Track function is enabled. Conversely, a logic "0" denotes that the function is not being performed or the condition does not exist.


Control Mode and Status Discretes
Translation Hand Controller
Attitude Hand Controller
Main Engine Signals
RCS Jet Discretes
Rendezvous and Landing Radar
Caution and Warning
LM Mission Programmer
LGC Uplink
Altitude Meters
AGS Initialization
DSKY Illumination
LGC Prime Power
Appendix A and B

   Pulse Waveform
   Glossary of Symbols

Apollo Guidance Computer and Other Computer History

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Last Revised: February 03, 2010
Web Grunt: Richard Katz