Here you'll find a collection of all the AGC, AGS, LVDC, and Gemini
spacecraft computer documentation and software that I've managed to
find whilst working on Virtual AGC. Every document on
this page is archived here at Virtual AGC, regardless of whether it
originated here or
not. In the early days I used to include only material I
uncovered by my own efforts, but
there have increasingly been contributions by readers, including
some of the original AGC developers. And there's material here
that has been duplicated from other Apollo-centric websites for your
convenience; see the FAQ page for a list of
the fine Apollo and Gemini websites I raided. Now, there is some value-added in this
process, since I add searchable text to those PDFs which are
image-only, as well as adding metadata and bookmark panes where they
don't exist. My intention is to eventually provide
one-stop-shopping for all of your Apollo and Gemini computing-system
documentation needs. Note however, that I choose to duplicate only
scanned or photographic images of the original documents. In
other words, I provide something as close to the "real thing" as I
can. On some sites, notably the Apollo Flight Journal and
Apollo Lunar Surface Journal, great pains have been taken to produce
HTML forms of the documents. I do not duplicate those improved reformulations here,
because that's original work for which I think credit is due; so you
will have to visit those sites to use those improved versions.
Various presentations presented at the MAPLD '04 conference, by
AGC developers and other knowledgeable folks
- Hugh Blair-Smith, "YUL System - Pass 0": video
- Ray Alonso, "Evolutionary Dead Ends": video
- Eldon Hall, "Historic Disassembly of a Block II Apollo
Guidance Computer": video
- Cline Frasier, "Digital Autopilot for Apollo: A Radical
- Jose Portillo Lugo, "Lunar Module Attitude Controller Assembly
Input Processing": text
- Also, various still photos related to these folks and their
manuals and listings
- Convenient HTML forms of AGC program listings, with syntax
colorization, cross-reference hyperlinks, and (a little)
- Or alternately, very
large scanned page images of AGC program listings, if you'd like
to see a crummy, compressed form of what the actual AGC
- E-1077: Preliminary MOD 3C
Programmers Manual, by R. Alonso, J. H. Laning, Jr., and
H. Blair-Smith, November 1961. (84 pages, 2.7M
bytes.) This manual applies to an earlier version of the
AGC, but is still very interesting since it includes topics like
the YUL assembler.
- AGC4 Memo # 9 -
Block II Instructions (1966), by Hugh Blair-Smith.
This is the source for
info on AGC assembly language. See also pages
30-50, provided as etext by Hugh Blair-Smith (rather than
being scanned) just for us. Incidentally, I've taken to calling this the
"infamous memo", simply because I think it's funny, but I notice that this phrase is being
duplicated across the web. I don't actually know that
there's anything infamous about it, so if you plan to quote
me, please leave out the word "infamous".
- E-2052: AGC4 Basic
Training Manual, Volume I, by Bernard
Savage and Alice Drake, January 1967. (118 pages, 3.9M
- "Users Guide to
the Block II AGC/LGC Interpreter", by Charles A. Muntz.
(1965, 3 Mbytes).
System Operations Plans (GSOP)
- AS - 278:
R-547: Guidance System
Operations Plan AS-278. AS-278 was a cancelled
mission (because of Apollo 1), which would have been the first
orbital test of the LM. Instead, the same crew provided
that first test in Apollo 9, at a much later date.
- Preliminary Lunar Landing Mission GSOP
- Apollo 5 Lunar Module: R-527: Guidance System Operations Plan for
Unmanned LM Earth Orbital Missions Using Program Sunburst:
- Apollo 8 & 9
Command Module: R-577: Guidance System Operations Plan for
Manned CM Earth Orbital and Lunar Missions Using Program
Colossus 1 (Rev. 237) and Program Colossus 1A (Rev. 249).
Don't be fooled by the name "operations plan". This is
detailed technical documentation specific to the mentioned
versions of Colossus---and
of course, Colossus 1A build 249 is the version we are actually
using. The "operation plan" is something like a "user
manual" for the guidance system (and hence for the AGC as
well). The complete document scan is about 1840 pages (43M
bytes), so I've split it into smaller chunks for more-sensible
1, Rev. 1: "Pre-Launch". (59 pages, 1.5M
2, Rev. 2: "Data Links". (138 pages, 4.5M
3, Rev. 3: "Digital Autopilots". (219 pages,
- Section 4, Rev. 6: "GNCS Operations":
- Section 5, Rev. 4: "Guidance Equations":
6, Rev. 1: "Control Data". (102 pages, 2.3M
- Apollo 9 & 10 Lunar Module: R-557: Guidance System
Operations Plan for Manned LM Earth Orbital Missions Using
Program Sundance 306, and Program Luminary 069:
- Apollo 13 Lunar
System Operations Plan for Manned LM Earth Orbital and Lunar
Missions Using Program Luminary 1C (Rev. 131).
The complete document scan is about 2300 pages (45M bytes), so
I've split it into smaller chunks for more-sensible downloading:
1, Rev. 1. (62 pages, 1.7M bytes.) Actually,
I took this section from document R-557: Guidance System Operations Plan for
Manned LM Earth Orbital Missions Using Program Sundance 306,
and Program Luminary 069. Refer to page v of
the document for an explanation of this oddity.
Unfortunately, there is presently no way to know if this is
the correct revision
of this section, but it was the latest revision I was able to
2, Rev. 8: "Data Links". (146 pages, 4.7M
3, Rev. 4: "Digital Autopilot". (194 pages,
- Section 4, Rev. 7: "PGNCS Operational Modes."
- Section 5, Rev. 8: "Guidance Equations"
6: "Control Data". (84 pages, 1.7M
bytes.) Unfortunately, there is presently no way to know
for sure if this is the correct
revision of this section, but it was the only revision I was
able to find. The document specifically refers to
spacecraft CM-107 (used on Apollo 11) and LM-6 (used on Apollo
12), so it's not unreasonable to suppose that it is a fairly
mature revision of the document. (Recall that we believe
Luminary 1C 131 was
used for Apollo 13.)
- Apollo 10 Command
System Operations Plan for Manned CM Earth Orbital and Lunar
Missions Using Program Colossus 2 (Comanche Rev. 44,45).
(Thanks to original AGC developer Fred Martin!)
- Section 5, Rev. 5: "Guidance Equations".
- Apollo 15-17 Command
System Operations Plan for Manned CM Earth Orbital and Lunar
Missions Using Program Colossus 3. (Thanks to
Shelly Kelly and the crew at U. H. Clear Lake!) Note that
several sections are actually taken from the Colossus 2E GSOP
rather than the Colossus 3 GSOP. Colossus 3 software was
used for Apollo 15-17, while Colossus 2E software was used for
Apollo 14. The GSOP documents were modular, and so
sections from various missions might be mixed-and-matched to
make a complete document, but I don't have a list of the
revision levels appropriate to Colossus 3. So it's
possible that the Colossus 2E sections exactly right; the most I
can say right now, though, is that they're the closest thing we
have to Colossus 3 docs.
1, Rev. 2: "Pre-Launch" (Colossus 2E, 61 pages,
2, Rev. 14: "Data Links". (Colossus 3, 155
pages, 5.6M bytes.)
3, Rev. 11: "Digital Autopilot". (Colossus
2E, 244 pages, 8M bytes.)
- Section 4: "PGNCS Operational Modes".
5, Rev. 14: "Guidance Equations". (Colossus
3, 493 pages, 11.3M bytes.)
- Section 6: "Control Data".
7, Rev. 01: "Erasable Memory Programs".
(Colossus 3, 98 pages, 2M bytes.)
- Apollo 15-17 Lunar Module: R-567: Guidance System Operations Plan for
Manned LM Earth Orbital and Lunar Missions Using Program
- Apollo/Skylab and/or Apollo/Soyuz: R-693: Guidance System
Operations Plan for Manned CM Earth Orbital Missions Using
Program Skylark 1:
quick-reference cards or data cards
Colossus 3 CMC Data Cards (36 pages, 1.5M bytes).
Same but for Apollo 15 CM. (Contributed by Fabrizio
Bernardini.) Also, Apollo 15 CMC
data cards. (This is a cleaned up version of the
scanned cards. Thanks, Fabrizio!)
15 Luminary 1E LGC Data Cards, (42 pages, 8.3M
bytes). Same but for Apollo 15 LM. (Contributed by
Fabrizio Bernardini.) Sorry, but this is a zipfile of
JPEGs rather than a PDF file, because that's the only way I
could keep the size even marginally manageable. These sets
of reference cards tend to have funky background colors, and
some colors are easier to scan than others. The JPEGs
should be very readable, but the scans Fabrizio sent me are much
better than what I'm posting (again, for size reasons), so if
you need better scans you should let me know.
quick-reference cards. (36 pages, 1.2M bytes.)
The Apollo CM spacecraft used for the Skylab project ran a
program called Skylark
on their AGCs. These quick-reference cards, presumably
used for training flight controllers, packed a lot of info about
Skylark (and indirectly
about Colossus and to a
lesser extent Luminary)
in a very concise package.
quick-reference cards (38 pages, 1.2M bytes) are the same
idea, except that they were used for the Apollo-Soyuz test
AGC pad loads
Regarding the Block II AGC schematics, I have heard that there is
a general attitude that they are incomplete, which is true, and
therefore inadequate for allowing one to construct a hardware
simulation of a Block II AGC, which is probably not true.
Mike Stewart, who has in fact built such a hardware simulation,
assesses the adequacy as follows (in slightly edited form):
[It depends] on what is meant by "complete". The logic
and interface modules are all present, so working
simulations/replicas of the *logic* of the computer, and its
connections to the outside world, are certainly possible
That being said, there are missing pages, which make
it more difficult (and less accurate/"complete") than it needs
to be. All of them are in Tray B and the DSKY. [There is
only one schematic page] for each -- the clock oscillator in
Tray B, and the power supply for the DSKY (D7).
The missing modules are, to my knowledge:
- Analog Alarms Module (B8):
- Filtering for the AGC warning light (the three
possible causes of this light were OR'd together in Tray
A, then shipped here for "filtering", but I don't know
what that entails)
- Voltage monitoring (announced through VFAIL)
- Oscillator monitoring (announced through OSCAL)
- Scaler module monitoring (announced through
- A start-up/restart signal whose exact cause I
haven't yet identified (STRT2), but probably has to do
with voltage stability
- Erasable Driver Module (B9-B10):
- Exactly as it sounds, took the signals generated
mostly by modules A14 and A15 and drove the core memory
- Current Switch Module (B11):
- This is probably used for driving the various
currents needed by the Erasable memory. In that
capacity, I assume it would receive some or all of the
signals ZID, SETEK, RSTKX/, RSTKY/, REX, REY, WEX,
and/or WEY, while the Erasable Driver Module handles
core selection with XT0E-XT7E, XB0E-XB7E, YT0E-YT7E, and
YB0E-YB3E. Or maybe the Erasable Driver Module gets all
of those, and has its own set of inputs to the Current
Switch Module. Or vice-versa! It's bound to be something
along those lines, at least.
- Module B12:
- If that's even a thing. There's a weird
wiry-looking thing between modules B11 and B13 on Tray
- Sense Amplifier Module (B13-B14):
- Sense signals from memory, one each for fixed and
erasable, and put them out on the sense amplifier lines
to fill the G register. Interestingly, we've got
drawings (maybe even labelled with values somewhere) of
the chips used on this board, but not the board itself.
- Strand Select Module (B15):
- Rope driving stuff, although I don't know why
it's separate from the Rope Driver module
- Rope Driver Module (B16-B17):
- The main rope drivers. Take signals from A14,
A15, and... A6 I think? and drive the ropes
- Indicator Driver Module (D1-D6):
- Contained DSKY relay driver circuits and the
Plus, any other ancillary information that wasn't
done on a circuit board like DSKY button wiring, pinouts,
backplane connections, and such that I can't put a number or
I'd argue that none of this is strictly necessary for
a "complete" simulation. Nobody's going to weave their own
core/core rope memory anyways... there's tons of ferrite cores
on ebay. I did the math. It would take years. So that
immediately drops the need for B9-10 and B13-17. It's possible
to implement your own versions that respond only to the
signals fed directly to those modules (ie without cheating),
which is how mine works. ...
The alarms module stuff can be done custom to the
application, or without the filter (FLTIN connected straight
to FLTOUT), or whatever.
There are enough partial drawings of the indicator
driver module that you can cobble something reasonably close
to the real thing together, albeit with probably different
relay decoding wiring (though there's less correct answers to
this than many seem to think) and component values.
THAT BEING SAID, as somebody trying to build a replica
that's as accurate as possible, all of these and any other
electrical/mechanical drawings are now at the top of my
Analysis (SGA) memos
If you are interested in the
mathematical underpinnings of the AGC software, then this amazing
series of memos from MIT's Instrumentation Lab is the place to
look. The memos are in roughly chronological order. It
is very interesting to reflect on the fact that these mathematical
memos are often written by the very same people whose names you
find as authors in the software. The AGC software was
written in a time ... or at least a place ... where software was
regarded as the expression of mathematical knowledge as opposed to
being a mere exercise in the expert employment of programming
languages and tools as it is today. It is interesting also
to reflect on the nature of the software this approach produced.
Data Needs, Terminal Display Devices, and Ground System
Configuration Requirements" by Richard A. Hoover.
- Guidance and Control Systems:
Control System for Unmanned Mission AS-201" by Gene F.
Module Abort Guidance System" by Pat M. Kurten.
Module Mission Programer" by Jesse A. Vernon.
Control Programer for Unmanned Missions AS-202, Apollo 4,
and Apollo 6" by Gene F. Holloway
Guidance, Navigation, and Control System Development",
by M. D. Holley, W. L. Swingle, S. L. Bachman, C. J. LeBlanc,
H. T. Howard, and H. M. Biggs.
Navigational and Alignment Software" by Robert T. Savely,
Bedford F. Cockrell, and Samuel Pines.
Miscellaneous Guidance &
These items are alphabetical by
author. (Where the "author" is an organization rather than a
person, I consider the author to be "Anonymous".) These
items are mostly documents are from our
of the now sadly defunct AGC website of
MIT's Dibner Institute for the History of Recent Science and
Technology. (Yes, there is some duplication here, but
otherwise it becomes all too easy to lose documents because
they're smeared across multiple web-pages.)
- Ramon L. Alonso, Hugh Blair-Smith, and Albert L. Hopkins, Some Aspects of
the Logical Design of a Control Computer: A Case Study
- Ramon L. Alonso et al., A Digital
Control Computer Developmental Model 1B (1962, 12 Mbytes).
- Ramon L. Alonso and Albert L. Hopkins, The Apollo
Guidance Computer (1963, 3 Mbytes).
- Ramon L. Alonso, Albert L. Hopkins, and Herbert A. Thaler, A
Multiprocessing Structure (1967).
- Ramon L. Alonso and J. Hal Laning, Design
Principles for a General Control Computer (1960, 4
- Anonymous, Apollo
15 Electronics manual, by Delco Electronics. This
document seems to have no title, document number, date, or
revision, but it is the most useful source in most respects for
information about interfacing the AGC to the remainder of the
guidance system. (Scanned by Frank O'Brien for the Apollo
Flight Journal / Apollo Lunar Surface Journal websites.)
16 Electronics manual, by Delco Electronics.
- Anonymous, Apollo Guidance
and Navigation Lunar Module Student Study Guide, by AC
Electronics. (1967, 9 Mbytes).
- Anonymous, Guidance
and Navigation, July 1965, training slides.
- Anonymous, Guidance
and Control, February 1967, training slides.
- Anonymous, Guidance
Control, September 1967, training slides.
- Anonymous, MSC05225, 71-FS-5: Program Notes for Colossus 3 and
Luminary 1E J-Series Missions Flight Programs, Rev. 1,
September 1972 (54 pages, 1.5M bytes). Program notes
written by the MSC Simulation and Flight Software Branch.
(Contributed by Fabrizio Bernardini.)
- Anonymous, LEM
CES and AGS, September 1966 (32 pages, 800K bytes).
This is a set of block diagrams and other high-level data
concerning the LEM. It is excerpted from a larger training
course by Grumman. (Contributed by Fabrizio Bernardini.)
- Anonymous, excerpts from LEM
Guidance, Navigation, and Control Subsystem Course No. 30315,
30415, March 1966 (40 pages, 8M bytes). Excerpts
from a Grumman study guide. (Contributed by Fabrizio
- Anonymous, beautiful photos of an early
LM control panel (September 1968) and the LMP's
panel (Apollo 14). (Contributed by Paul Fjeld.)
- Anonymous, Drawings
of LM structures. (Contributed by Paul Fjeld.)
- Anonymous, The Apollo 11 Adventure.
(247 pages, 8.8M bytes.) A quirkily geekish retrospective
of the Apollo missions through Apollo 11, from the perspective
of the Mission Planning and Analysis Division. (Digitized
by me at the National Archives.)
- Anonymous, Astronauts'
Guidance and Navigation Course Notes (1962, 3 Mbytes).
- Anonymous, More Apollo
Guidance Flexibility Sought (1964).
- Anonymous, Control of
Flight Software Development Costs (1971).
- Anonymous, Apollo/Skylab
ASTP and Shuttle Orbiter Major End Items (1978).
- R. Battin et al., The Compleat
Sunrise being a description of Program Sunrise (Sunrise 33 -
NASA DWG# 1021102) (1964, 4 Mbytes).
- Hugh Blair-Smith, Annotations
for Eldon Hall's book, Journey
to the Moon: The History of the Apollo Guidance
Computer (1997). This is an etext created
by Mr. Hugh Blair-Smith, rather than a scan of a historical
- D. J. Bowler, Auxiliary
Memory System, Final Report on Phase I (1968).
- Edward M. Copps Jr., Recovery from
Transient Failures of the Apollo Guidance Computer (1968).
- Robert Crisp and D. Keene, Apollo Command
and Service Module Reaction Control by the Digital Autopilot
S. Draper volunteering to become an astronaut, and Robert
Seamans replying (1961).
- C. S. Draper et al., Space
Navigation Guidance and Control. Volume I. (1965, 7
- C. S. Draper et al., Space
Navigation Guidance and Control. Volume II. (1965, 63
- Charles M. Duke Jr. and Michael S. Jones, Human
Performance during a Simulated Apollo Mid-Course Navigation
Sighting (1964, 5 Mbytes).
- J. C. Dunbar, R. A. Larson and P. T. Augart, An Automated
Documentation Technique for Integrating Apollo Crew Procedures
and Computer Logic (1966).
- Maxime A. Faget, The Evolution
of Flight Control of the Apollo Mission (1976).
- Philip G. Felleman, Hybrid
Simulation of the Apollo Guidance Navigation and Control
- Frank E. Gauntt, Digitally
Controlled Pulse Torquing of Precision Intertial Instruments
- F. K. Glick and S. R. Femino, A Comprehensive
Digital Simulation for the Verification of Apollo Flight
- Alan I. Green and Joseph J. Rocchio, Keyboard
and Display System Program for AGC (Program SUNRISE)
- Alan Green, Digital
Development Memo #267: Vlock II Keyboard and Display Program
- Alan Green, Keyboard and
Display Program and Operation (1967, 4 Mbytes).
- Alan I. Green and Robert J. Filene, Keyboard and
Display Program and Operation (1967).
- The Guidance Software Validation Committee, Apollo Guidance
Software Development and Validation Plan (1967).
- Eldon C Hall, The Apollo
Guidance Computer - A Designer's View (1982).
- Eldon C Hall, Case History of
the Apollo Guidance Computer (1966, 3 Mbytes).
- Eldon C Hall, A Case history
of the AGC Integrated Logic Circuits (1965).
- Eldon C Hall, Computer
- Eldon C Hall, From the Farm
to Pioneering with Digital Computers: An Autobiography
- Eldon C Hall, General Design
Characteristics of the Apollo Guidance Computer (1963, 3
- Eldon C Hall, MIT's Role in
Project Apollo, Vol. III: Computer Subsystem (1972, 11
- Eldon C Hall, Reliability
History of the Apollo Guidance Computer (1972).
- Eldon C Hall and Richard Jansson, Miniature
Packaging of Electronics in Three-Dimensional Form (1959,
- James A. Hand, Computer-Aided
Inertial Platform Realignment in Manned Space Flight
(1968, 31 Mbytes).
- James A. Hand, MIT's Role in
Project Apollo, Vol. I: Project Management, Systems
Development, Abstracts and Bibliography (1971, 13 Mbytes).
- David L. Hanley, Jayne Partridge, and Eldon C. Hall, The Application
of Failure Analysis in Procuring and Screening of Integrated
Circuits (1965, 3 Mbytes).
- W. G. Heffron, Bellcomm memorandum, "S/C
101 Software First Article Configuration Inspection",
- David G. Hoag, Apollo
Navigation, Guidance, and Control Systems: A Progress Report
(1969, 4 Mbytes).
- David G. Hoag, The History of
Apollo On Board Guidance and Navigation (1976).
- David G. Hoag, LEM Guidance
Computer Programs to be Supplied by MIT (1965).
- C. Lester Hogan, "Types of
Integrated Circuits" (1964) [Magazine Article].
- M. D. Holley, W. L. Swingle, S. L. Bachman, C. J. LeBlanc, H.
T. Howard, and H. M. Biggs, "Apollo
Report—Guidance and Control Systems: Primary Guidance,
Navigation, and Control System Development", NASA
Technical Note D-8227.
- Richard A. Hoover, "Apollo
Experience Report—Flight-Control Data Needs, Terminal Display
Devices, and Ground System Configuration Requirements",
NASA Technical Note D-7685.
- Albert L. Hopkins Jr., Ramon Alonso, and Hugh Blair-Smith, "Logical
Description for the Apollo Guidance Computer (AGC4)"
(1963, 10 Mbytes) [Report].
- Albert L. Hopkins, "Electronic
Navigator Charts Man's Path to the Moon" (1967).
- Albert L. Hopkins, "A
Fault-Tolerant Information Processing Concept for Space
Vehicles." (1970) [Report].
- Madeline S. Johnson, "A
list of titles and authors", MSJ Memo #7-69. I
deduce from this numbering scheme that Madeline must have
written a lot of
- Madeline S. Johnson and Donald R. Giller, "MIT's Role in
Project Apollo, Vol. V: The Software Effort." (1971, 30
- Malcolm W Johnston, "A Manual LEM
Backup Guidance System." (1964) [Report].
- David N. Kaye, "The
Indispensible Men" (1969) [Magazine Article].
- W. M. Keese et al., "Management
Procedures in Computer Programming for Apollo - Interim Report"
- Allan R. Klumpp, "A Manually
Retargeted Automatic Descent and Landing System for LEM"
(1966, 3 Mbytes) [Report].
- Allan R. Klumpp, "Apollo
Lunar-Descent Guidance" (1971).
- J. Hal Laning and N. Zierler, "A Program for
Translation of Mathematical Equations for Whirlwind I."
- T. J. Lawton and C. J. Muntz, "Organization of
Computation and Control in the Apollo Guidance Computer"
- Jonathan Leavitt, Portafam
System Operational Description (1969).
- Stuard D. Lenett, "Apollo
Digital Up-Data Link Description", NASA Technical
- Frederick H. Martin and Richard H. Battin, "Computer
Controlled Steering of the Apollo Spacecraft" (1967)
- Frederick H. Martin and Richard H. Battin,
"Computer-Controlled Steering of the Apollo Spacecraft," Spacecraft,
5 (1968, 4 Mbytes), 400 - 407.
- J. McNeil, J. E. Miller and J. Sitomer, "Use of Body
Mounted Inertial Sensors in an Apollo Guidance, Navigation and
Control System" (1966, 4 Mbytes) [Report].
- John E. Miller and Ain Laats, "Apollo Guidance
and Control System Flight Experience." (1969) [Report].
- George Mueller, "Final Report:
Apollo Guidance Software Task Force" (1968) [Report].
- J. V. Mutchler, "Apollo CMC/LGC
Software Development Plan" (1968, 3 Mbytes) [Report].
- J. L. Nevins, "Man-Machine
Design for the Apollo Navigation, Guidance and Control System."
(1967, 21 Mbytes) [Manuscript].
- J. L. Nevins and I. S. Johnson, "Man-Computer
Interface for the Apollo Guidance, Navigation and Control
System" (1967, 9 Mbytes) [Report].
- J. L. Nevins, I. S. Johnson and T. B. Sheridan, "Man/Machine
Allocation in the Apollo Navigation, Guidance, and Control
System" (1968, 24 Mbytes) [Report].
- J. L. Nevins, E. A. Woodin and R. W. Metzinger, "Man-Machine
Simulations for the Apollo Navigation, Guidance, and Control
System." (1967, 3 Mbytes) [Report].
- James L. Nevins, "Man-Machine
Design for the Apollo Navigation, Guidance, and Control
System--Revisited: Apollo, A Transition in the Art of Piloting
a Vehicle." (1970, 3 Mbytes) [Report].
- Robert N Noyce, "Integrated
Circuits in Military Equipment" (1964) [Magazine Article].
- Jayne Partridge, L David Hanley and Eldon C. Hall, "Progress Report
on Attainable Reliability of Integrated Circuits for Systems
Application" (1964, 5 Mbytes) [Report].
- J. C. Pennypacker, "Whole Number
Strapdown Computations" (1966, 3 Mbytes) [Report].
- Daniel Rankin, A Model of
the Cost of Software Development for the Apollo Spacecraft
Computer (1972, 5 Mbytes) [SM dissertation, MIT].
- Robert T. Savely, Bedford F. Cockrell, and Samual Pines, "Apollo
Experience Report—Onboard Navigational and Alignment Software",
NASA Technical Note D-6741.
- Dave Scott, transcript
of remarks about the AGC.
- Norman E. Sears, "Technical
Development Status of Apollo Guidance and Navigation"
(1964, 3 Mbytes) [Report].
- Edwin D. Smally, "Block II AGC
Self-Check and Show-Banksum" (1966) [Report].
- Raymond D. Speer, "Strict Control
Kept Out Semiconductor Flaws" (1969) [Magazine Article].
- Madeline M. Sullivan, "Hybrid
Simulation of the Apollo Guidance and Navigation System"
(1965, 3 Mbytes) [Report].
- B. K. Thomas, "Apollo 8 Proves
Value of Onboard Control" (1969, 3 Mbytes) [Magazine
- Milton B. Trageser and David G. Hoag, "Apollo
Spacecraft Guidance System" (1965, 25 Mbytes) [Report].
Abort Guidance System
(AGS) and its computer (AEA)
As inadequate as our AGC
documentation collection is, our AGS documentation collection lags
far behind. All of the available documentation was digitized
by John Pultorak from physical documents preserved and donated by
- "LM/AGS Design Survey"
- Just the block
of the AEA. (Actually, John had to outlay
money for this, as it's not one of Davis's docs, so we have
additional cause to thank him. He also tells us it's the
best AEA architecture diagram he has seen.)
Flight Program 8 -- LM
AGS FP8 S03 4039, LM Abort Electronics Assembly,
12/18/70, 6325 lines. Complete assembly language
Operating Manual, Flight Program 6, 11176-6033-T000,
Revision 1, TRW, July 1969, 194 pages, 36.1M bytes.
Computer Program Specification,
Flight Program 6, 11176-6042-T000, TRW, March 1969, 90
pages, 14M bytes.
- Memo: Tables
and Flow Charts for Preliminary Release of FP8, C. G.
Gibson, TRW, 5 January 1971, 2.1M bytes.
Electronic Assembly Programming Reference, H. L.
Stiverson, 7322.3-17, April 1966, 77 pages, 14.6M bytes.
This document is the principle (and almost complete) reference
for understanding the operation of the AEA CPU per se, the AEA assembly
language and assembler, and the operation of the CPU's i/o
ports. There are, however, some confusing aspects to the
- Perhaps the most confusing thing is that while the portion
of the document that covers the LEMAP assembler makes it clear
that the integer -1 would be encoded in octal as 0777777 (as
anyone working with a modern PC would expect), the portion of
the document that covers assembly language repeatedly refers
to the octal 0400000 as being "-1". (More specifically,
the reference on these occasions is to "A0 = 1, A1 thru A17 =
0", where A0 is the sign bit and A1-A17 are the data
bits.) In fact, this octal pattern encodes the "largest"
18-bit negative number, namely -131072. In this detail,
the assembly-language portion of the manual is thus incorrect.
- Perhaps the most serious omission is that the explanation of
division (the DVP
instruction) in the case where the dividend and/or divisor is
negative is completely lacking and (in the absence of this
explanation) I've never figured out satisfactorily how it is
supposed to work
- LM AGS, Programmed Equations Document, Flight Program 6,
11176-6041-T0-00, TRW, 1969 April. Because of the size, we
provide this in 2 chunks:
Verification Test Results, LM/AGS Flight Program No. 6,
11176-6050-T000, E. V. Avery, TRW, Redondo Beach CA, May 1969,
49 pages, 13.8M bytes.
AGS Guidance Software, Final Design Report, Flight Program 6,
11176-6052-T0-00, TRW, Redondo Beach CA, April 1969, 10 pages,
AGS Flight Equations, 05952-6076-T000, T. S. Bettwy, TRW,
25 January, 1967, 117 pages, 20M bytes.
Flight Program 6, LM 5 Mission Constants,
11176-6055-R0-00, C. J. Mabee, TRW, Redondo Beach CA, June 1969,
25 pages, 3.2M bytes.
Guidance System, Performance and Interface Specifications
Document, Preliminary, July 1, 1966, 345 pages (not
numbered), 46.2M bytes.
Guide for AGS Bit-by-Bit Simulator, Bulletin
672-21-EAS-208, K. B. Robertson, Lockheed, Houston TX, August
1968, 67 pages, 12M bytes.
CES and AGS, Grumman, September 1966, 32 pages, 800K
bytes. (I think this is available elsewhere on the web,
but it's a different scan.)
Experience Report—Guidance and Control Systems: Lunar Module
Abort Guidance System" by Pat M. Kurten, NASA Technical
Launch Vehicle Digital Computer (LVDC)
We have precious little LVDC
documentation of any kind, and no LVDC software at all. The
Wikipedia article on the LVDC laments that all of the LVDC
software has probably vanished and does not exist any
longer. Well, I don't believe that. (They're smart
enough to send a man to the moon, but too stupid to put the
documents in a file cabinet afterward? I hope not!)
There must be some former LVDC developer somewhere who was proud
enough of his work to retain some souvenirs. If you know any
LVDC developers, please help us to get in contact with them.
- Laboratory Maintenance
Instructions for LVDC. While the title of this
document is undoubtedly correct from the standpoint of IBM (the
corporate author), the document is more usefully viewed as a
complete explanation of the theory of operation of the LVDC,
albeit of a very early breadboard version.
- IBM 63-928-137, Saturn
V Guidance Computer, Semiannual Progress Report.
This sounds like a managerial thing, but is actually is a huge
- MSFC IV-4-401-1, Astrionic
System Handbook, Saturn Launch Vehicles. Chapter 11
is particular relevant to the LVDC, as it discusses the flight
software in some detail. Sadly, it does not show any
actual sample snippets of LVDC software.
- MTP-ASTR-S-63-15 Saturn
IB/V Astrionics System.
- Bellcomm memo, "Memory
for the Launch Vehicle Digital Computer (LVDC)" by J. J.
- Bellcomm memo, "Launch
Digital Computer (LVDC) Requirements for the Apollo
Applications Program" by J. J. Rocchio.
- MSFC III-5-509 Saturn 1B/V
Instrument Unit System Description and Component Data:
- NASA Technical Note D-5869, "Description
and Performance of the Saturn Launch Vehicle's Navigation,
Guidance, and Control System" by Walter Haeussermann.
- Boeing document, "Saturn
V Launch Vehicle Guidance Equations, SA-504".
- MTP-AERO-63-64, "An
Iterative Guidance Scheme for Ascent to Orbit (Suborbital
Start of the Third Stage" by Isaac E. Smith and Emsley T.
- NASA Technical Note D-2967, "Application
of an Iterative Guidance Mode to a Lunar Landing" by
Helmut J. Horn.
- Here's a set of short documents contributed by Eldon Hall to
klabs.org, providing a comparison of the (proposed) AGC to the
(proposed) LVDC, and pertaining to the notion of replacing the
AGC by the LVDC in the CM and LM. I suppose these
documents may be interesting in a historic sense, and in some
cases are mildly amusing, but they are interesting to me
principally because some of the documents are very rich in
technical information about the LVDC.
- MSFC-MAN-206, Skylab Saturn IB Flight Manual.
- MSFC-MAN-503, Saturn
- S&E-ASTR-S-101-69, Technical
Information Summary, Apollo-11 (AS-506).
- MSFC-MAN-507, Saturn
V Flight Manual, SA-507.
- NASA Technical Memorandum X-53384, "The
Astrionics System of Saturn Launch Vehicles" by Rudolf
- IBM Saturn
Instrument Unit Fact Sheet.
- NASA Technical Memorandum X-53350, "Saturn
Instrument Unit Command System" by H. R. Lowery.
- NASA Technical Note TN D-4481, "Saturn
V Manual Backup Guidance and Control Piloted Simulation Study".
- NASA Technical Memorandum, "Report
on Digital Computers Used in Automatic Checkout" by B.
- NASA Technical Memorandum X-53274, "Techniques
of Implementing Launch Automation Programs (Saturn IB Space
Vehicle System)" by William G. Bodie.
- NASA Technical Memorandum X-53398, "Saturn
I Block II Guidance Summary Report" by R. A. Chapman.
- TR-612, Saturn
IB and Saturn V Computer Programs, Software Status Report.
- NASA SP-4206, Stages
to Saturn by Roger E. Bilstein. This is actually a
book in the NASA History Series, so it isn't as technical, but
is full of all sorts of contextual detail that is missing from
the technical documents.
110A (Saturn ground computer) Mathematical Subroutine Manual.
Dimitri Marinakis (thanks Dimitri!) sent me this. The
ground computer which which the LVDC cooperated was an RCA
110A. "Mathematical Subroutine Manual" sounds very
exciting until you find that it means "multiplication",
"division", "cosine", "sine", etc. It is still an
interesting document, in the sense that it reveals what life was
like for the computer programmer in that time-frame. These
algorithms are each accompanied by RCA 110A assembly language
showing exactly how they were implemented, and give the full
theory for each method, duly written up as if the description
was a mechanical drawing, with a proper page border appropriate
to such a drawing, and accompanied by notations such as the
units, scale, and tolerance of the drawing! I've chosen to
provide it only as a tarball of JPEG page images rather than to
convert it to a PDF (which would take twice the storage), and I
hope nobody minds that. The image at right (supplied by
Dimitris Vitoris) is a photo of an unknown (to me) assembly from
- Lunar Module Systems
- Excerpts from LM-5
through LM-9, June 1969 (13 pages, 29M bytes).
This is a large download because it consists of beautiful
hi-res scans of very large wiring-diagram foldouts.
(Contributed by Paul Fjeld.)
- Excerpts from Apollo
17 (3 pages 5M bytes). Sadly, these scans are not
of the highest quality. If you seek general information
rather than Apollo 17 specific information, I'd suggest the
item above or the item below instead. (Contributed by
- Command and Service Module
- Excerpt: Guidance & navigation section (including
wiring diagrams) for handbook of CSM
112 through 114, March 12, 1971 (29 pages, 20M
(Contributed by Fabrizio Bernardini.)
Operations Handbook, Command and Service Module, Spacecraft
012. (This was the Block 1 spacecraft for Apollo 1.)
- Apollo Operations Handbook,
Block II Spacecraft:
- Volume 1:
- Alternate excerpts. (Contributed by Fabrizio
- LMA790-3-LM, Apollo
Operations Handbook, Lunar Module:
1 (LM 10 and subsequent), "Subsystems Data"
2 (LM 11 and subsequent), "Operational Procedures"
- Alternate excerpts. (Contributed by Fabrizio
- Lighting tables.
interior and exterior lighting. (Contributed by Paul
Operational Data Books
- "G", "H", and "J" missions: CSM/LM
Spacecraft Operational Data Book:
Technical Crew Debriefings
General Apollo documents unrelated
to computing systems
Press Kits and Releases
- Project Gemini
Familiarization Manual, contributed by Adam Bootle to
the Meadville Space Center website. As far as the onboard
computer is concerned, it is Section VIII that is
relevant. This describes (among other things), the
on-board computer architecture, memory layout, and CPU
instruction-set. The links at Meadville indicate that
Volume 1 is for spacecraft GT-3, GT-4, and GT-7, while Volume 2
is for GT-5, GT-6, and GT-8 through GT-12. If you are only
going to look at one of them, look at Volume 2 Section VIII.
Summary of Gemini Software History", a short memo about
the versioning of Gemini OBC software, up and including
GT-10. (Provided by Dick Jasinski via Gene Mertz.)
presentation slides (?), giving a summary of the OBC, it's
software, and peripherals in 80 pages ... possibly for astronaut
This unique and document was written by original Gemini
programmers Charlie Leist and Jim Condell, and describes
programming the on-board computer from the programmers'
perspectives; as such, it discusses various pragmatic
difficulties rather than just the theoretical ideal, though it
also covers the on-board computer's CPU instruction set and
similar topics in a way that both overlaps and differs from the
"Guidance and Control Systems" documents listed in the item
above. Charlie has additionally (in 2011) thoughtfully
recreated a missing document page for us. It's a big
download (49MB for 35 pages) because I didn't have the heart to
reduce the resolution of the scan, but it's indispensible if
you're interested in the on-board computer software.
- Detailed Math Flow diagrams. (I.e., very detailed
flowcharts of the software design for the flight software.)
Math Flow from 1963 (prior to ATM), with Alden Minnick's
handwritten notes. (The illegible notes at the left margin of
p. 17 are: "TE = AT LIFT OFF T" and "TE
> TE0 = LIFT OFF".)
& Fast Ascent only, from 1963. See pp. 2-3 of
the linked document. The document (actually, Appendix E)
contains a lot of other helpful stuff like detailed
explanations of the variables, some additional theory, and
source code of a FORTRAN implementation. I'm not really clear
where this goes in the development chronology, merely that it
is a few months later than the corresponding elements from the
Detailed Math Flow in the preceding entry. The Appendix
comes from the following report, of which we don't have an
electronic version at present, but may be able to provide one
in the future: "Preliminary
(Analytic Report No.
No. 63-564-0159, 31
January 1963, by D.P.
Bedford, R.E. Cofer,
T.W. Hill, R.B.
Jasinski, J. Park, J.R.
Sims, R.V. Wadding.
III only (Catch-up & Rendezvous) from 1966 (post ATM)
Catch-Up and Rendezvous Analysis and Simulation Report #4",
contributed by Gene Mertz and scanned by Dave Mertz. This
"report" actually contains the full source code for the mixed
FORTRAN II and IBM 7090/7094 assembly language program that was
used to verify algorithms and simulate flight-computer behavior
for the Catch-Up and Rendezvous flight phases. Therefore,
although it is not flight software per se, it is presently the closest thing we
have to Gemini flight software. There are also 5 fold-out
flowcharts which are split into multiple pages in the PDF, which
I've pulled out, deskewed, rescaled, and rejoined. They're
not perfect, but they're a little easier to read than the pages
in the PDF file:
for Use in Gemini". Contributed by OBC developer P.
J. Holcombe (c/o Gene Mertz). Some of the constants listed
no longer agree with current values, but they're what were used
at the time. According to our best understanding at
present, the symbol Φ is the gravitational potential. Gene adds that he
thinks that "the angle, phi (f) in the three-term
expansion of the earth's oblate geo-gravity model, is measured
from the ascending node of a Gemini orbit rather than latitude."
Orbit Calculation", a 1962 hand-written memo, presumably
by Gene Mertz, regarding issues such as roundoff and step size
in the Gemini orbital calculation.
orbit rate compensation note, handwritten by Gene Mertz.
of Fixed Point Orbital Navigation Using Modified Euler
Integration and a Two Term Potential Function", memo by
Gene Mertz. (There are some hand-drawn corrections on the
first page that may be hard to read. In two places it say
"t+h", and later in the same paragraph, the y in "y=f(t)" has
- Here are some supplemental non-Gemini documents (mostly from
History Museum) which may be of assistance in
understanding the FORTRAN dialect, the assembly language, and
the operating system under which the simulation program from
Report #4 above ran. At any rate, I found them useful in
porting the code to make it portable to more up-to-date
- Gemini Operations Handbook
7, Sections 2.5.2-2.5.7. This is something like a
user manual for the Gemini computer. Contributed by Dr.
Lance Erickson to Meadville.
10, Sections 3.8.1. This is the command set for
the Agena target vehicle (ATV), and nothing to do with the
Gemini computer per se. Contributed by John Bisney to
- Gemini Mission Reports:
Last modified by Ronald Burkey on