Journey to the moon : the history of the Apollo guidance computer

255 Pages·1996·8.42 MB·English

by  Eldon C Hall

JOURNEY TO THE MOON:
The History of the
Apollo Guidance Computer
c.
Eldon Hall
Publis.hed by the American Institute of Aeronautics an.d Astronautics, Inc.
1801 Alexander Bell Drive, Reston 20191-4344

American Institute of Aeronautics and Astronautics, Inc., Reston, Virginia
Library of Congress Cataloging-in-Publication Data
Hall, Eldon C.
Journey to the moon: the history oftlle Apollo guidance computer
I Eldon C. Hall.
p. em.
Includes bibliographical references and index.
L Project Apollo (U.S.)-History. 2. Space flight to the moon-··
Data processing-History. 3. Electronic digital computers-United
States-De.sign and construction-History. 4. Space vehicles-United
States--Guidance systems····Design and construction-History.
L Title.
TI.789.8.U6A5383 1996 629.45'3·-dc20 96·42188
ISBN [··56347·185·X
Second Printing
Cover design by Susan Raynor
Copyright © 1996 by the American Institute of Aeronautics and Astronautics. Inc. All rights reserved. Printed in the
United States of America. No part of this publication may be reproduced, distributed, or transmitted. in any form or by any
means, or stored in a database or retrieval system, without the prior written permission of the publisher.
Data and IIIf ormation appearing in this book are for informational pUlposes only. AIAA and the author are not responsible
for any injury or damage resulting from use or reliance, nor does AIAA or the author warrant that use Of reliance will be
free from privately owned rights.

Contents
Illustrations ................................................................................................................................ ix
Foreword .................................................................................................................................. xix
Preface ...................................................................................................................................... xxi
Acknowledgments ................................................................................................................... xxv
Introduction ................................................................................................................................ 1
Pa rt I. History ............................................................................................................................ 7
Chapter 1 Computer Hardware .................................................................................................. 11
Circuit COlnponents ......... ,. . ,. ..... , ........ ' ....................................................................................... 11
Memory Components ................................................................................................................. 24
Interconnections .............. ' .......................................................................................................... 25
Chapter 2 Computers ................................................................................................................. 31
Commercial ................................................................................................................................ 34
Aerospace .................................................................................................... '" ............................ 34
Chapter 3 MIT Instrumentation Laboratory .............................................................................. 37
Polaris Guidance System ............................................................................................................ 38
Polaris Computer ........................................................................................................................ 40
Architecture ................................................................................................................................ 40
Hardware .................................................................................................................................... 43
Flight Experience .............................................................. ,. ........................................................ 44
Mars Mission Study .................................................................................................................... 46
Part II. Apollo Hardware ........................................................................................................ 49
Chapter 4 Requirelnents ............................................................................................................ 53
Mission ....................................................................................................................................... 53
Schedules .................................................................................................................................... 53
Industrial Contractors ................................................................................................................. 57
Guidance and Navigation ........................................................................................................... 59
Guidance Computer ....................................................... '" .......................................................... 63
Chapter 5 In The Beginning-Apollo Computer ...................................................................... 69
Design ......................................................................................................................................... 69
Interfaces .................................................................................................................................... 73
Chapter 6 Winds of Change Were Blowing ............................................................................... 79
Integrated-Circuit Proposal ........................................................................................................ 82
The Second Generation .............................................................................................................. 85
Mission Success ............................................................................................. ,. ........................... 92
Chapter 7 Block I COluputers .................................................................................................... 95
Flight Prototype .......................................................................................................................... 95
v
vi Eldon C. Hall
Production ................................................................................................................................. 100
8 System .................................................................................................. 103
Interference .................................................................................................... 103
Alanl1s ......................................................................................................................... 107
Interference-Apollo 6 Mission ................................................................................... 107
Chapter 9 Naysayers and Advice from Outside ......................................................... 1.11
10 Ncxt-Generation--Block H ................................................................................... 117
1964 ............................................................................................... 119
Characteristics .......................................................................................................................... 119
Architecture ........ '" ..................................................................................................................... 120
Circuits ................................................................................... 125
"U.,,,,,JU Hardware .................................................................................................................... 127
....................................................................................................................................... 127
Production ................................................................................................................................. 128
Evaluations ............................................................................................................................... 128
1 Revisited ............................................................................................... 133
Chapter 12 Reliability ................................................................................................................. 139
Design ...................................................................................................................... 140
Selection ................................................................................................................ 140
Evaluation and Qualification .................................................................................................... 141
Procedures ......................................................................................................... 145
Procurement ............................................................................................................ 145
.................................................................................................................................. 146
Acceptance ................................................................................................................... 146
of Results ................................................................................................................. 147
Part III. Apollo Software ....................................................................................................... 151
~"".,,~, 13 Sofhvare ........................................................................................... 155
Apollo Software in the Days ........................................................................................... 155
Software 'fools ....................................................................................................... 156
................................................................................................................... 157
..... u"IJ'~, 14 Mi~sion Software ................................................................................................... 16J
System .............................................................. ,. ....................................................... 161
Executive and Waitlist ............................................................................................................... 162
................................................................................................................................. 163
Restart and Self-Check ............................................................................................................. 165
.................................................................................................................. 166
Verification ............................................................................................................................... 169
Mission ............. , ..................................................................................................... 171
15 Finale ................ , .............. , ........................................... , ........................ , ................ 179
Apollo 11 .......................................................................................................... , ....................... 179
] 2 .................' ............................................................................................... ,. ................. 180
Apollo 14 .................................................................................................................................. 181
Wonders Did Unfold ................................................................................................................. 181
Contents vii
Appendix ................................................................................................................................. 183
Index ........................................................................................................................................ 193
Plate Section .................................................................................. " ....................... after page 63

Illustrations
Figure 1 Mission
Courtesy Charles Stark Laboratory Archives
Photograph Number 3
Figure 2 Tree
Courtesy Charles Stark Draper Laboratory Archives
Photograph Number 119941 10
Figure 3 Single-bit binary adder
Photograph Number 10201 12
4 NOR logic gate
Photograph Number 10200 13
Figure 5 Circuit component revolution
Photograph Number 10202 14
6 Gennaniumjunction transistor
Photograph Number 10203 15
Figure 7 Silicon planar transistor
Photograph Number 10204 16
Figure 8 Integrated circuit
Photograph Number 10205 17
9 TI proposed packages
Charles Stark Draper Laboratory Archives
Photograph Number 22561 18
Figure 10 Midget logic module, TI integrated circuits
Courtesy Charles Stark Draper Laboratory Archives
Photograph Number 24033 19
11 NOR logic gate
Photograph Number 10206 25
Figure 12 Handmade interconnections, early 1950s
Courtesy Charles Stark Laboratory Archives
Photograph Number 17 26
Figure 13 Printed-board assembly, late 1950s
Courtesy Grabbee Museum 27
14 Hybrid electronics assembly
Courtesy Grabbee Museum
Photograph Number 46581 28
Figure 15 Wire-wrap interconnections
Courtesy Charles Stark Draper Laboratory Archives
Photograph Number 20564 28
Figure 16 Guidance and control equations, form
Courtesy Charles Stark Draper Laboratory Archives
Photograph Number 119946 39
Figure 17 Guidance and control equations, fonn
Courtesy Charles Stark Draper Laboratory Archives
Photograph Number 119933 39
Figure 18 DDA symbolic diagram
Courtesy Charles Stark Draper Laboratory Archives
Photograph Number 119936 41
Figure 19 DDA functional diagram
Photograph Number 10207 41
ix