AGC — AGS — LVDC — Gemini
or at least, Frequently Given Answers
browser to see a site-search form here.
How can I help?
Is this site mirrored anywhere?
Is there a Wiki for this project?
If you have AGC/AGS information you'd
like to contribute, you could do
so by contacting me directly. However a more straightforward
approach may be to contribute
to the wiki
. Examples of things that are
useful are theoretical discussions, historical information or
anecdotes, tutorials on how to perform certain tasks with the AGC or
AGS, etc. Editing of the wiki is members-only, and you will find
instructions for requesting membership at the link just given.
Yes, this is a hassle, but it's a one-time thing and it helps to keep
the wiki reliable.
Is there a mailing list for this project?
There is! If
you'd like to subscribe, changes the preferences of your existing
subscription, or unsubscribe, go to
I expect this to be a very
low-traffic mailing list, devoted to very technical questions, if my
own inbox is any indication. :-) However, as with any
mailing list, you're taking your chances. It's a members-only
mailing list, so hopefully you'll be spammed by it only if spammers
spoof the email address of existing members. Also, there are
various options you can set for your subscription, such as concealing
your email address from the group. (I think I'd still be able to
find out your email address, since I administer the list, but you'd
just have to live with that.)
You might also want to look at Orbiter
, where they seem to be making great
on the practical details of actually using the AGC for running
simulated missions. Highly recommended if you're more interested
in running the AGC rather than understanding its guts!
Wow, where did you get all this material, and how can I find some
If you want to collect AGC
documentation and software in a secret shrine where you can admire it
without sharing the content with anybody else, please don't.
Sometimes you can find this stuff on eBay. There are also
auctioneers who buy and sell this stuff. Obviously, we (Virtual
can't afford to buy it there or anywhere else, but if you find yourself
doing so please
consider sending us a digital copy. The value of your collectable
won't be dimished and you'd be doing a public service.
Sadly, a lot of information that would be very helpful for this project
does not seem to be publically available on the Internet. For
where is a dimensioned drawing of the DSKY? What connector types
used for feeding external signals to the AGC, what was the pinout of
connectors, and what were the electrical characteristics of those
Where are additional source-code versions of Luminary
... or of Sundance
software)? (I could go on like this all day.) Alas! I don't
know the answers to these and many other questions. One can only
hope that the materials still exist somewhere and may become available
someday. If you would like some
hints about where this kind of information may be lurking, click here
Fortunately, just enough information has been readily available to
allow development of Virtual AGC. All of the materials we've
collected are available from our document library
I have some of the documentation you need, but what can I do with
Is this project affiliated somehow with NASA, or Draper Labs, or
TRW Aerospace, or IBM, or ... are
Apollo workers involved?
No, not in terms of running it or
providing any of the simulation software. However, in latter
years it has been gratifying to see contributions of archived AGC
documentation and program listings by various of the original AGC
And who the heck are you, anyway?
Well, I'm not involved in the space
program in any way. Professionally, I write embedded software for
airborne devices. I have a number of other open-source projects,
which you can read about (along with a more-extended write-up about me,
Me, ME!) at my main website
And yes, somebody really did ask this.
Why waste so much time on a project that may be of interest to 3
Placing men on the moon is one of the
greatest accomplishments of the United States of America. It is
indeed, that it is the greatest
accomplishment (of any kind) in the
history of the human race. If so, perhaps it makes sense to
preserve the relics of the Apollo project. (Besides, I'm one of
the 3. )
I got the idea while watching the movie Apollo 13
. The instant in the
movie where the AGC is powered up on Earth approach is the instant when
the viewer suddenly feels that survival of the astronauts has changed
from "highly unlikely" to "very probable". It gives me a chill
whenever I see it. Anyhow, on watching this one day, it struck me
that it was a shame nobody knew any longer how to operate the AGC—let
alone write the programs for it. (As it happens, that thought was
a bit premature: only 35 years had passed since the AGC software
was written, thus many of the original software developers were still reasonably
Nevertheless, the principle is correct, since very few
people could use or
program the AGC.)
Anyway, it then occurred to me that it would be cool to bring the AGC
back to life, and to allow anyone so inclined to use it or program it
... assuming, of course, that sufficient publically information was
available to do so. As it quickly turned out, there was enough
information publically available, though just barely
project turns out to be an interesting experiment in digital
: I found a
couple more geeks, bringing the total to 5. Here's their website
they're doing almost the same thing as me, inspired (no less) by From the Earth to the Moon
Later news flash:
found still more geeks. Let's just assume that the total is
around 100 and do away with these further news flashes!
Tom Hanks, Wherever You Are, Call Me!
I jest, of course. But I suspect
that if Tom Hanks (a well-known space buff) had an assistant make a few
judicious telephone calls to people hoarding the AGC-related
information we need to advance this project, it could accomplish more
in a few hours than years of knocking on doors by me has accomplished.
If you know someone like Tom (or know someone who knows someone like
Tom) who might be sympathetic, pass the word along to them.
What's with the "ya" stuff all over the place?
Computer programmers are aware—though
Apollo enthusiasts may not be—that "ya" is often added to
computer program names to mean "yet another". Thus, yaYUL is "yet another YUL", yaDSKY is "yet another DSKY", and so on.
What's the deal with "verbs" and "nouns"?
The following amusing (if not
necessarily helpful) comment may be found in
the source code of the keyboard and display program (otherwise known as
IS PROVIDED THROUGH THE COURTESY OF THE AUTHORS.
PROVED TO THY FACE THAT THOU HAST MEN ABOUT THEE THAT
USUALLY TALK OF A NOUN AND A
VERB, AND SUCH ABOMINABLE WORDS AS NO
CHRISTIAN EAR CAN ENDURE TO HEAR."
HENRY 6, ACT
2, SCENE 4
It turns out, though, that the authors' literary skills didn't quite
match their programming skills, as this quote is really from Henry VI,
Part 2, Act IV, Scene VII. (Thanks to Frank O'Brien of the Apollo
Flight Journal and Apollo Lunar Surface Journal for this
correction.) By the way, if you take it upon yourself to actually
read the play to figure out the context, you may find yourself reading
about "a Nowne and a Verbe" rather than "a noun and a verb".
Original AGC hardware developer Ramón Alonso provides a little
more insight: Apparently,
nobody had yet arrived at any kind of software requirements for the
AGC's user interface when the desire arose within the Instrumentation
Laboratory to set up a demo guidance-computer unit with which to
impress visitors to the lab. Of course, this demo would have to do something, if it was going to be
at all impressive, and to do something it would need some software. In
short order, some of the coders threw together a demo program,
inventing and using the verb/noun user-interface concept (in the
whimsical fashion seen in much of this code), but without any idea that
the verb/noun concept would somehow survive into the flight
software. As time passed, and more and more people became
familiar with the demo, nobody got around to inventing an improvement
for the user interface, so the coders simply built it into the flight
software without any specific requirements to do so.
However, that does not mean that the verb/noun interface was
universally beloved. Ramón says that many objections were received from
naysayers, such as "it's not scientific", "it's not dignified", or even
"astronauts won't understand it". Even though the coders of the
demo hadn't seriously intended the verb/noun interface to be used in
any permanent way, it became a kind of devilish game to counter these
objections with (perhaps) sophistic arguments as to why the interface
was really a good one. In the end, the coders won. I don't
know whether they were elated or dismayed by this victory.
The astronauts, of course, could
understand the interface, but they did not like it. Most of them
really wanted an interface much more like that they had used in
aircraft: i.e., lots of dials and switches. Dave Scott is
the the only astronaut I'm aware of who had kind words for it (or for
the AGC in general), though we are told that Jim McDivitt wasn't
necessary completely hostile to it.
Why Isn't More Information Provided About Why the Guidance System
User Interface Was Like it Was?
A lot of thought about usability went
into the design of the guidance system, much more so than the story
above about verbs and nouns would indicate. Questions like what
kinds of controls needed to be provided, or even where those controls would be
physically located, were extremely important (Thanks to George
Silver for pointing this out.) Sadly, I don't know anything about
these topics, and that's why I don't cover them here.
Tell Us More Amusing Stories
Well ... maybe just a couple more.
- The story of the 1201 and 1202 alarms on the descent by Armstrong
and Aldrin to the lunar surface during Apollo 11 is well known.
(If you don't know it, the astronauts received repeated alarms from the
AGC of type 1201 and 1202 -- 5 alarms in all, if I'm not
mistaken. On each alarm, the question was raised as to whether to
continue or to abort. Obviously, they continued.) I'm
informed that the representative from the MIT Instrumentation Lab who
was present to be consulted by Mission Control was Russ Larson.
When consulted on the go/no-go question, Larson simply gave a "thumbs
up" signal. When asked years later why he had done this, he said
simply that he was too scared to speak. (Thanks to Allan Klumpp
for this story.)
- And continuing on the topic of the 1201/1202 alarms in Apollo
11: These alarms were caused by the fact that during the landing,
both the landing radar and
the rendezvous radar were turned on. Only the landing radar
actually needed to be active, but it was felt by some that having the
rendezvous radar turned on would be useful in case of a sudden
abort. What wasn't known was that this extra load on the AGC CPU
would cause it to run out of processing cycles. The software
would work all right at first, but eventually the loss of about 15% of
the CPU cycles due to processing the excess radar data would cause some
tasks to be spawned before earlier instances of those tasks had
completed running. Eventually, because of the duplication of
tasks, the software would be unable to allocate the memory needed to
spawn new tasks, and would need to restart. Fortunately, the
cunning design of the software allowed the software to basically
continue executing at the same point where it had been before
restarting, and so it could continue operating normally until it ran
out of memory again. Eldon Hall likes to point out that this is a
success of the AGC rather
than a failure (as some other
people like to say). At any rate, Allan Klumpp coded a workaround
for this problem in time for the Apollo 13 mission, but the
powers-that-be declined to use the new software. Klumpp was upset
enough about this to contact the mission commander, Jim Lovell, and
describe why the new software (Luminary 131) would be so much better
than the old. The next morning, Dick Battin dropped by Klumpp's
office and announced, "Allan Klumpp, your political savoire-faire has descended to a
new low!" That was his way of saying that Luminary 131 would be
used on Apollo 13 after all, because Jim Lovell wanted it.
- The original source code for the AGC assembler program called
"YUL" isn't presently publicly available, though I expect it will be
soon, and I'll link to it when it is. However, here is a scan of pages 2 and 3 of the
listing for YUL. Please examine it closely. I needn't
- Not an AGC story, but I like it: I'm told that one of
the perks of writing software at MSC in the Apollo era was
taking the coding sheets to the 'swamp' for the
keypunch operators to build the card decks to be taken to the computer
center. The 'swamp' was a tiered auditorium with many young
women at keypunch machines on the tiers. Of course, the
would enter the room at the front at what was the focus of the
tiers, feeling a little like a bull at the rodeo auction.
Apparently, this was a good way to meet bored young women in need of
stimulation. This is a case, obviously, where progress has been
in completely the wrong direction. (Thanks to Paul Schlein for
- When the disks containing the Apollo 11 assembly listings arrived
(May 2009), the shipping clerk who handed the box to me asked if it
contained a software update. I informed him that it did.
That it was a very old software update ... in fact, perhaps the oldest
software update in the history of the world. And you know
what? I think it may actually be true.
Wouldn't it be better to incorporate Virtual AGC into a flight
or lunar landing simulation?
Yes. I would strongly encourage
But it's outside of my personal limits, workload-wise. If you
want to work on that, I may be able to connect you to other people who
are also interested in doing so.
If you do want to work on this, I'd strongly
advise that you use (or adapt and improve) the socket-based
interconnect model I've provided and described on the developer page
(so that yaAGC can be used as
a stand-alone program), rather than trying to cut-and-paste yaAGC
code into the
flight-simulator. Remember that even though Virtual AGC is free
of cost, you are still bound by the licensing provisions of the General Public License
(GPL); in other
words, there are consequences for misuse of the code. If, for
example, you insert yaAGC
into a flight simulator, then that flight simulator must also be
open-sourced under the GPL, or else I would have to grant you a special
exception to the license. (For example, I have granted such an
exception for the Orbiter
program. See below.) On the other hand, if you use yaAGC
as a stand-alone program that
merely communicates with the flight simulator, then there is no such
problem. Remember also that Virtual AGC is a work-in-progress,
and if you insist on customizing yaAGC
itself, you will have to carefully consider what you intend to do when
I improve it without consulting you, and you have no way to merge the
Work to integrate Virtual AGC into the Orbiter
spacecraft simulator has proceeded marvelously.
There is a Sourceforge project
with working code and documentation such as installation instructions.
I'm told that integration into FlightGear
is proceeding well
also, though I have not heard anything about it for several years.
How come the stuff the simulation can do is so trivial?
It takes more than just a computer to
fly an Apollo LM or CM. At the very least, you need simulations
of the spacecraft's IMU, AOT, and of the physical spacecraft (i.e.,
acceleration, torque, fuel usage, etc.). Maybe we'll have those
things, one of these days. The LM-Simulator
module has made a
good start towards providing some of these things.
It doesn't work! How do I make it work?
It's Too Slow!
At the moment, Virtual AGC consists of
two parts: the core programs (like yaAGC
, etc.) and the contributed LM-Simulator
separate them because very different techniques and tools were used for
creating them, so they don't contribute to slowing down you computer in
the same way. Furthermore, the contributions of the various parts
are different on different platforms. Here are some approximate
timings I've made using the 20050716 development snapshot:
|Mac OS X
While the benchmarks above are very far out of date technology-wise by
now, they are still somewhat instructive. What you'll notice,
undoubtedly, is that the simulation is going to
need a relatively modern system to run all of the bits and
pieces. If you don't
have a fast enough CPU, it doesn't observably affect the core programs,
has the symptom that LM-Simulator
slows to a crawl, and responds increasingly slowly as time goes on,
because the backlog of unprocessed data increases.
So what is to be done about this? Well, I'm sure that over time
we'll be able to improve the speed of these programs, but that's not of
any immediate help to you. One thing you can do immediately,
you have the resources, is to take advantage of Virtual AGC's
client-server architecture. You can do things like running LM-Simulator
on one computer, and
the core programs on another computer. Splitting up the
bits and pieces this way has the additional advantage (if each computer
has its own monitor) of making it easier to see all of the various
controls without having them obscure each other.
Of course, if you're so inclined, you could also roll up your sleeves,
pitch in, and help us figure out how to speed up the simulation
Troubleshooting Running the Simulation
Various things to to look out for are
found in the quirks
, but here's a separate, supplemental list just to make it even
- If you're running the simulation by separately running yaAGC and yaDSKY rather than through the VirtualAGC GUI, remember that
the two programs have to be
run from two different command-line windows. A reason why you
might want to do this is that
on some slow Win32 systems, there are
some timing problems if the startup scripts are used.
- VirtualAGC enforces a
certain ordering in the way the various components of the simulation
start up. If you bypass VirtualAGC,
note that there
some are some quirks in the
startup and shutdown ordering of yaAGC
and yaDSKY. If you don't stick to my recommended
ordering, you will probably encounter problems. In Win32: You can't start
peripherals before you start yaAGC;
do, the programs will
not be able to communicate amongst themselves. In Linux (pre-20050131): You
can't terminate yaAGC before
peripherals; if you do, there will be
a timeout (which may be a minute or two) before the operating system
allows the port connecting the simulated CPU and peripherals to be
reused. (In Win32, command "netstat
-a" --- or in Linux, the command "netstat -a | grep 19697" --- is
useful for detecting this condition.) The startup/shutdown
procedure I'd recommend for both platforms is:
- Start yaAGC.
- Start all peripherals (like yaDSKY).
- Use to your heart's content.
- Stop all peripherals (like yaDSKY).
- Stop yaAGC.
- Startup of the LM-Simulator
component, which is written in the Tcl/Tk scripting language, has
always been problematic: If it doesn't connect within a certain
limited time, it will abort, and if the simulation is being run from
the VirtualAGC GUI it will
generally cause the entire simulation to abort. One thing that
seems to help is to delay startup of LM-Simulator
for several seconds, to insure that yaAGC
is up and waiting for connections before LM-Simulator even tries to connect.
- The main place (I think/hope) where things could go wrong would
be in the TCP socket interface connecting yaAGC and yaDSKY. If some
other service on your computer was already using port 19697—if, for
example, you were simultaneously running two copies of yaAGC or yaDSKY—then there could be a
problem. You can check this by closing
all instances of yaAGC and yaDKSY (in Win32 with ctrl-alt-del,
or in Linux with "killall -KILL
yaDSKY" and "killall
-KILL yaAGC"), and then trying this: "telnet localhost 19697".
If telnet says it connected to something, then you definitely have
another service using this port, and you can work around it with the
--port command-line switch of yaAGC
and yaDSKY to choose a new
port. If not, then you
probably don't, and that's not the cause of your problem.
- Another possibility, I suppose, is that you may have a personal
firewall installed which is blocking port 19697. In that case,
have to reconfigure the firewall.
- Perhaps your computer is not even set up properly for networking,
which is necessary for any of the socket-based communications to
work. For example, you may not have an Ethernet card. These comments from Joe Durnavich
(thanks Joe!) may help if you have this problem and you're using Linux.
How do I Uninstall this Thing?
On Linux or Windows, an uninstaller
program is provided when the installer program is run.
on Mac OS X or from source code—simply remove the installation
directories which were created. Unless you've renamed them, these
will be folders with
names like "yaAGC/" (dev snapshot), "VirtualAGC/" (Linux binaries),
"Virtual AGC\" (Windows binaries), or "VirtualAGC.app/" (Mac OS X
binaries. On very old versions, in Linux or Mac OS X, the installation
directory might have been "~/.yaAGC".
I'm drowning in Alphabet Soup! What does it all mean?
Assembler---the LM's hand-controller for pitch/roll/yaw adjustments.
|Abort Electronics Assembly.
|Apollo Guidance Computer
|Abort Guidance System---a
separate computer aboard the Lunar Module
Telescope. Telescope used to make star sightings. By
monitoring the orientation of the telescope, the AGC could compute the
orientation of the spacecraft and use this information to calibrate the
IMU (see below).
|The Command Module---i.e., the
|Command Module Computer---i.e.,
the AGC in the CM.
|The combined Command and Service
|Guidance and Navigation
|CM G&N Control System---i.e,
the AGC plus G&N measurement and control devices.
|Inertial Measurement Unit.
This a stable platform (i.e., retains its orientation with respect to
the fixed stars rather than to the spacecraft) containing
accelerometers. By monitoring the accelerometers and the
orientation of the platform with respect to the spacecraft, the AGC can
compute the orientation of the spacecraft, as well as its position,
velocity, and acceleration.
|Lunar Guidance Computer---i.e.,
the AGC in the LM.
|The Lunar Module---i.e., the
|Launch Vehicle Data Adapter
|Launch Vehicle Digital Computer
|("Pings".) The LM Primary
G&N Control System---i.e,
the AGC plus G&N measurement and control devices.
Are there other websites I should look at?
There are lots of online sites with
resources, though not necessarily specializing in the AGC. Some
terrific ones are listed below, in no particular
à la Lune. This site is in French, but you
don't have to speak the language to admire that amazing Apollo-related
graphics and videos presented there.
Fabrizio Bernardini (whose help I've acknowledged in a number of places
on the Virtual AGC website) has put together this spacecraft-related
site. It's only in its beginning stages, and isn't devoted to
Apollo exclusively, but does have Apollo-related (and specifically
AGC-related) material on it.
Not to mention the fact that it's pretty sharp looking!
Many valuable Apollo technical
drawings and other references. The following links were
particularly valuable for me:
Office of Logic Design has various interesting AGC-related
documents online. There's not a lot of unique content yet, but
strides are being made and it looks like there soon will be, so it's
worth checking out.
which links an interesting collection of Apollo (and Mercury,
Gemini, and shuttle) docs from a diverse set of websites.
Space Center Library has press kits for all of the missions.
nice Apollo site, with the highlight (for my purposes)
useful miscellaneous info, including spacecraft photos.
doesn't contain any actual materials of interest to Virtual
AGC, as far as I can tell, but it's very useful in figuring out where
existing records from Apollo are physically located.
general-purpose Apollo site with some unusual
miscellaneous information (such as Block I DSKY photos). You need
to read French, though, which I unfortunately do not.
15 Lunar Surface Journal site has this very interesting
manual by Delco, covering many aspects of the Apollo 15 mission, but
(in particular) computer operation. Thanks to Mark Grant for
pointing this out.
paper by José Portillo Lugo, describing everything
may ever want to know about the LM's hand-controller, and how it
interacts with the AGC.
- "Tales from the
Lunar Module Guidance Computer", transcript of a terrific talk by
Don Eyles, covering the infamous Apollo 11 1202 alarms, the Apollo 14
solder-ball incident, and more.
- And last, but not least, the Apollo Lunar Surface Journal
Journal(s). But I imagine that anybody who has managed
to find their way here already knows all about them anyhow.
Here are sites of some folks who are
doing pretty much the same kind of
stuff as I
- John Pultorak
has recreated a working
Block I AGC, has recreated
some of its software and back-ported some Block II software to it, and
offers us instructions for doing the same. Must see!
Webb. Click here to see
Julian's abstract for the September 2004 MAPLD conference.
Bucher et al.
Here are links to some apparently
pretty realistic full-feature LM
simulations, but (of course) without true AGC simulations except
insofar as efforts have been made to integrate Virtual AGC with
not tried any of them myself, except for briefly messing with Orbiter.)
The home of Eagle Lander 3D, a lunar-lander simulator,
freeware as of this writing, but with a commercial version
of the ISIS lunar-lander simulator.
of the freeware Orbiter space-flight
simulator. There is an Apollo add-on for Orbiter, called "NASSP", and there
is work being done to integrate Virtual AGC into the CSM portion of the
add-on, started by Mark Grant and continued by Markus Joachim.
Apparently, that work is at or near a usable (if not complete) state,
which in my (admittedly prejudiced) view is very
cool. Here is the latest word I have on it from Markus (with a
little editing from me):
just want to inform you that I finally released my stuff "Virtual
Apollo". It's available at SourceForge together with it's "parent
Orbiter add-on" called "Project Apollo - NASSP". You can find it here: http://sourceforge.net/projects/nassp/.
Apollo documentation is also available online: Look here http://nassp.sourceforge.net/ and
The Virtual AGC integration" link.
With "I finally released my stuff" I don't mean
[that the integration of Virtual AGC] is finished or that this is the
final release.... :-). My stuff isn't
finished; the IMU is working fine, but optics, RCS, the DAP and so on
are still missing.... [Later] I plan to do a tighter integration
of the Virtual AGC in Project Apollo.... But I suppose it will be
months (or years) until all this is finished. Perhaps Mark Grant will
help with that; more help, any comments or suggestions are
Apollo - NASSP is not only an Apollo CSM add-on but it contains
the complete Apollo missions including a fully functional LM, mission
specific textures, the Skylab, the Saturn 1b missions... A really
huge add-on! But "Virtual Apollo" covers only the CSM and there only
lift-off and earth orbit insertation.
Update: I've also received the following comments from Mark to
indicate that the integration effort continues to make great progress:
have the AGC functioning up to orbit and outputting something
resembling the correct numbers on the DSKY.... Actually, we are
[working on an LM simulation also]. The Virtual Apollo release only had
the Saturn V, but we've also got the Saturn 1b and LEM. The LEM AGC is
up and running the Luminary code, but currently doesn't do much other
Emulators for other spacecraft-borne
computers, such as the Gemini
computer, the Apollo LM Abort Guidance System (AGS), the Apollo launch
vehicle inertial guidance system (LVDC), or the shuttle computer (4pi
flight computer, as an add-on for Orbiter.
of this project is still (as of 2004-09-13)
in the planning stages, due to a lack of hard information on the
computer. However, there are already some great scanned Mercury
and Gemini docs,
such as a Gemini computer user manual, Gemini spacecraft manuals, Agena
command set, and so on.
Write directly to Robert
Conley if you have
additional documentation or
the Gemini computer, or useful contact information.
... And some folks who are doing
nothing relevant, but cool and
possibly interesting to anybody interested in Virtual AGC.
- The Druantia Project,
to create "a 1:1 scale (in terms of both size and
resolution) working model" of the entire planet of Mars. Gosh!
used in developing for Virtual AGC. Modern Linux
distributions typically provide all of the tools needed, if not in a
default installation at least in the distribution's package system for
painless download. Win32, in contrast,
provides none of them.
(Hey, folks, they're free. It wouldn't cost Microsoft anything to
provide them.) Mac OS X is somewhere in between.
|GNU gcc, make, etc.
automatically by almost all Linux distributions.
developer CD, or download from www.apple.com.
provided automatically. Note that although GNU tools are assumed (www.gnu.org), native tools may work
|wxWidgets cross-platform GUI
toolkit for building VirtualAGC,
yaDSKY2, yaDEDA2, and yaACA2.
automatically by many Linux distributions. Otherwise, download
||Provided in Mac OS X 10.5, but you may need to update.
The version provided in Mac OS X 10.4 is too early, so download
||If not provided, download
|gtk+ cross-platform GUI toolkit for
building yaDSKY and yaDEDA.
No longer needed for the yaDSKY2
and yaDEDA2 programs that have
superceded yaDSKY and yaDEDA!
many Linux distributions. Otherwise, download
Otherwise, download from www.gtk.org
|Optional glade GUI builder for gtk+.
No longer needed for the yaDSKY2
and yaDEDA2 programs that have
superceded yaDSKY and yaDEDA!
many Linux distributions. Otherwise, download
Otherwise, download from glade.gnome.org
| POSIX Threads for
|Allegro cross-platform GUI toolkit
for building yaACA.
No longer needed for the yaACA2
program that has
some Linux distributions. Otherwise, download
Otherwise, download from alleg.sourceforge.net
|bzip2 for unpacking development
|tar for unpacking development
scripting language for LM_Simulator.
What books and movies do you recommend?
- The Apollo Guidance Computer:
Architecture and Operation, by Frank O'Brien. Chichester,
UK: Springer/Praxis Publishing, 2010. The title says it
all. I think you'll find this to be a very readable book,
somewhat like a much kinder, gentler form of this website in terms of
the material presented. Conversely, some of the material on this
website came from Frank originally, so I guess what goes around comes
around. Good job, Frank!
- Journey to the Moon: The
History of the Apollo Guidance Computer, by Eldon Hall.
Reston, Virginia: American Institute of Aeronautics and
Astronautics, 1996. If
you're at all interested in the stuff on my website, buy this book and
read it. It's much more technical than you probably
imagine from the title. I have an autographed copy, purchased
from the author. The sign on the table read, roughly, "Signed by
the author -- $50. Unsigned -- $55." (And no, that's not a
misprint. Either price was a bargain compared to amazon.com, so I
cleverly bid it up to $60.) Also, you should read Hugh
- This New Ocean, by
William E. Burrows. New York: Random House, 1998. A
very comprehensive and seemingly authoritative history of the space
program up to 1998.
- Carrying the Fire: An
Astronaut's Journeys, by Michael Collins. New York:
Copper Square Press, 1974. Very funny.
- Deke! U.S. Manned Space:
From Mercury to the Shuttle, by Donald K. "Deke" Slayton with
Michael Cassutt. New York: Forge, 1994.
- The Last Man on the Moon,
Cernan and Don Davis. New York: St. Martin's
- A Man on the Moon, by
Andrew Chaikin. New York: Penguin Putnam, 1994. Upon
which From the Earth to the Moon
(see below) is partially based.
- Moon Lander: How We
Developed the Apollo Lunar Module, by Thomas J. Kelly.
Washington: Smithsonian Institution Press, 2001.
- Flight: My Life in
Mission Control, by Chris Kraft and James Schefter.
Penguin Putnam, 2001.
- Failure is Not an Option,
Kranz. Berkley Books, 2000.
- Apollo 13, Universal
- From the Earth to the Moon,
- Spacecraft Films
a series of DVD-sets containing the films, television transmissions,
still photos, and numerous other materials for various
missions---Apollo 8, 11, 15, 16, and 17 as of this writing.
I've seen the Apollo 11 and Apollo 15 sets, and would recommend them
for enthusiasts (but not for the friends and families of
enthusiasts). The Gemini films, on the other hand, seem
extremely compelling. One reader, Eugene Dorr, writes with rave
reviews about a video called "Mission to the Moon", which is a 2-DVD
set of documentaries; the star of the show (he tells us) is a half-hour
film called "Computer for Apollo", which includes a demonstration of
the AGC, as well as "a totally engrossing demonstration of how the AGC
was manufactured." I guess I should go an buy it myself, right
- In the Shadow of the Moon
is a terrific documentary by David Sington on the various lunar
missions, consisting principally of interview material with a large
number of Apollo astronauts. It doesn't really have anything to
do with the AGC, but I'd recommend it highly anyway.
- The AGC
episodes of the Science Channel series "Moon
Machines". This has lately also become available on DVD.
Is the moon landing a hoax?
Yes, though I've removed all references
the hoax from the Luminary and
Colossus source code.
But I must congratulate those 1960s tricksters on their attention to
detail, such as seeding copies of software listings for various
versions of the AGC software in people's homes, museums, and what-not,
so as to send me on expensive merry chases to find them and make them
publicly available 40 years later. And to do it in such a way
that with my dull, cowlike mentality I can't perceive the fakery in
it. Usually it takes a beautiful woman or somebody waving a
fistful of dollars at me to deceive me so badly. I mean, the
gosh-darn software actually works when you run it! You really
have to admire the level of commitment those evil geniuses had back
then. I doubt that today we even retain the skills to fake
anything so thoroughly. That's why former President Bush's
(faking) a return to the moon or visit to Mars is doomed to
But seriously, I've found the blog of some thinker who has used the
existence of our Virtual AGC project itself as evidence that the moon landing was
faked. His reasoning goes as follows: a) Virtual AGC
simulates some Apollo hardware; b) therefore, it is possible to simulate Apollo
missions; and c)
therefore Apollo missions were
fake 40 years ago.
Well, you hardly need Virtual AGC as a step in that reasoning, since
lots of people already know that the astronauts trained extensively in
simulated spacecraft. The simulators being used in the 1960s and
70s were far better and more accurate than our 21st-century
How can the Virtual AGC project be contacted?
Last modified by Ronald Burkey on 2010-08-11.