Hide 2026 change notes?
2026-01-06
Daniel Dang has contributed two new Shuttle docs for our library, checklists for STS 41-C (in contrast to the checklists for STS 51-A we added a couple of days ago).  I've also corrected a typo in the title of one of the Skylab docs added at the end of last year.
2026-01-02
Oops!  I forgot to mention that the two Shuttle documents contributed yesterday were sent in by Andrew Wilcox.  Thanks Andrew, and please excuse my tardiness!
2026-01-01
Jencir Lee has suggested some changes to the styling of the Virtual AGC website intended "to make it visually appealing and readable on a mobile device".  That's actually an impossible task, I fear.  For one thing, a lot of the website is devoted to presenting hundreds of thousands (millions?) of scanned images of 1960's-era documents or computer printouts that are highly unsuitable for viewing on narrow cellphones.  But even the textual exposition I've supplied on the web pages is illustrated by lots of figures that need side-by-side comparisons too wide for cellphones or are simply inherently wide in themselves.  Nevertheless, after fussing and screaming for several days about it, I've come around to the idea that even if mobile-device viewing is only going to be enhanced marginally, the modified styling is nevertheless a little more attractive when viewed in a desktop browser.  Which immediately made it a little more interesting to me.  Of course, being me, I couldn't accept Jencir's new styling as-is, but the changes I've made are certainly based very closely on the suggestions.  Thanks, Jencir!

The changes are subtle, though, so I wouldn't be surprised if nobody had even noticed them without being warned in advance.  If perchance you have some problem with them, let me know.  The changes are easy enough to undo.  Then too, it turns out that the Virtual AGC website is really big — had you noticed? — so while I've skimmed through a lot of the pages to see how the new styling has affected them, I can't claim to have looked at every single page of the website, nor to have looked in tremendous detail at the ones I actually did check.  So if you notice any oddities introduced by the new styling, do let me know!

On the subject of mobile-device viewing of Virtual AGC, it's not something I had given much thought to before.  And that's in spite of the 4,631 spam emails I've gotten from purported web developers who want to make the Virtual AGC website suitable for mobile devices.  (No, those emails I immediately mark as spam, just as I have with the 19,722 spam emails from SEO experts who promise to maximize the profit from my Virtual AGC "business".  My "profit" from this "business" are already maximized, thank you, at $0 USD.  Oh, who am I kidding?  The "profits" are negative.) 

However, this styling issue has caused me to spend a little time looking at Virtual AGC on mobile devices.  My findings were that with or without the styling changes, the Virtual AGC website is surprisingly good on cellphones in landscape mode, or on tablets.  For cellphones in portrait mode, it's more of a mixed bag:  useless on lower-resolution phones (say, with a width of 720 pixels) but very marginally useful if you have eagle eyes on higher-resolution phones (say, with a width of 1080 pixels).  Or not too bad if your browser gives you a text-zoom control that you can crank up to (say) 150%.  My general advice for cellphone users?  Use landscape mode and stop worrying about it.

As far as substantive changes are concerned, there were only two:
  • The addition of an alternate process for providing me with ITAR documentation as the prerequisite to providing you with a copy of LVDC source code.  If you want LVDC source code but haven't yet followed through on the old ITAR process because it's too clunky or inconvenient ... well, you won't enjoy the alternate process any better, I'm afraid, but it has some advantages.
  • Two new documents were added to the Shuttle Library page.

A boo-boo in the title of one of the documents most-recently added to the main library was also fixed.

Hide 2025 change notes?
2025-12-29
Mike sent over the two volumes of the Skylab Operations Handbook for the Apollo Telescope Mount for our library, as obtained via FOIA by Frederick Drew with help from Hugh Evans.  Thanks to all of the chefs contributing to this particular dish, particularly since they're the only Christmas delicacy I have to offer you this year!
2025-12-01
Removed a project from the AGC "physical implementation" page, due to advice from it's developer that it's now no longer available.
2025-11-03
Added five more documents to the library today.  According to Mike's summary, "Here's a set of new scans for you. The AMS manuals in particular are pretty exciting, with volume 2 giving both step-by-step instructions for setting up simulations, as well as a complete listing of simulator outputs, which gives us a pretty decent insight into the level at which each subsystem is simulated."
  • Apollo Operations Handbook, Volume 2, CSM 108 and Subsequent
  • Apollo Operations Handbook, Volume 2, CSM 112-115 — this is a new/higher-quality scan of a revision already in the library
  • Mercury Capsule Flight Operations Manual Capsules 11 and 15 — I don't think we have much Mercury stuff in the library, due to lack of computer, but I had the opportunity to scan this.
  • Apollo Mission Simulator Instructor Handbook, Spacecraft 012, Volume I, Description and Utilization
  • Apollo Mission Simulator Instructor Handbook, Spacecraft 012, Volume II, Instructor Workbook

Regarding the Operations Handbooks, I'd note that they're for Apollo 12 and 16. 

And regarding the AMS manuals, I'd note that they're for Apollo 1.  Be aware that according to their internal "lists of effective pages", we have only partial scans of them ... although it's not immediately clear to me by skimming the PDFs that there are actually any missing pages in the PDFs, so perhaps those lists of effective pages are full of hooey.  I hope so, anyway!    Regardless, it is what it is, and we'll take whatever we can get.

2025-10-14
  • Added some clarifications due to Dan Weaver (thanks, Dan!) to the XPL page.  As it happens, that page had already been largely superseded by the XPL-I page, which apparently didn't require clarification, but better safe than sorry!
  • Rory Ward (thanks, Rory!) has contributed the dissertation for his master's degree to the document library.  Its subject is the gradual introduction of software-engineering principles to the AGC software-development process, an introduction which he attributes largely to Margaret Hamilton.  If you're interested in software engineering — or for that matter, history of technology —, as opposed merely to the technical details of the AGC software or hardware, it makes for interesting reading.
2025-10-09
Added 10 documents to the library, as usual due to the efforts of Mike Stewart.  It's quite a miscellany.  Here's his synopsis:
  • Project Gemini Flight Crew Countdown
  • V-20035, Launch Vehicle Overall Test (Plugs Out), Released for AS-502
  • AAP Electrical Power System BCR Briefing
  • Worst-Case Analysis of the Switch Selector MOD II
  • LSI Log, July 1969 — this is an internal newsletter for LSI, which discusses their contributions to the program, notably including the DSKY electroluminescent screen
  • Apollo Block II ECS Components — this is the CSM equivalent to the LM ECS booklets by Hamilton Standard we already have in the library
  • Skylab S-191 Site Map Data Package, Flight Support Edition
  • Illustrated Parts Breakdown, Model A7LB Apollo, Skylab & ASTP Space Suits
  • A folder of PGNCS-related materials from the MIT Community Convocation, February 1969
  • AS-501 LIEF Operations Plan

I've also received some additional engineering drawings since my last update — two months ago! — but with luck they'll be part of an ongoing stream of new engineering drawings into the future, and I want to get some operational details worked out before posting any of them, so as to be able to present them in a consistent way that's also hopefully consistent with our existing cache of engineering drawings.  So we'll see.

2025-08-11
I've added 20 documents to the library today, which Mike got from correspondent Max-Q (thanks!), who in turn got them from the "Neil A. Armstrong Papers" collection in the Purdue University Archives.   With one exception, all of these documents are previously-missing memos (COLOSSUS, LUMINARY, or SUNDANCE) or problem/anomaly reports.  Recall that SUNDANCE was a predecessor program to LUMINARY, flown only in the Apollo 9 LM.  If you follow the link given above, it looks like there were more than 20 documents added, but that's because some of the memos are duplicated twice or even thrice due to overlapping memo-numbering schemes.  Apparently we had no SUNDANCE memos (or PCRs or Software Anomaly reports) prior to this, so I've added a new SUNDANCE Memos section in the library.  (Actually, "DANCE Memos" since the original developers for some reason didn't feel like adding the SUN prefix in SUNDANCE.  Go figure!)

I very much appreciate filling in this conspicuous gaps in our document coverage.  It would be great if we could eventually fill in all of the gaps.
2025-07-25
Added a couple of documents to the library, through a complicated chain of custody , apparently from Dave Mohr, to Jackson Tyler, to Mike Stewart, to me.  I offer kudos to all involved, myself excluded since I'm afraid of spraining my shoulder if I pat myself on the back too hard.  I suppose that the journey of these documents was no more complicated than that of most of the Apollo documents we've already received ... the only difference being that I was told more about it than usual, rather than having the documents drop upon me from the sky like manna from heaven.   (And just about as rarely!  But who am I to complain?)

Mike summarizes:  Both documents relate to the Saturn V electrical support equipment: a Bellcomm memo discussing its interlock system, and a partial set of schematics for the ESE.
2025-07-19
Building Virtual AGC on Windows presently requires the use of a programming environment called MSYS2.  A user has pointed out that the Virtual AGC build process was failing with newer versions of MSYS2 than the one I have been using.  (Thanks to Evilcaysen23 — apparently, not so "evil" after all — for this info and for testing out my proposed fixes.)  At any rate, changes to the Virtual AGC source code tree have been posted, as have updates to the build instructions for Windows, so hopefully builds in Windows can now proceed again until another crop of versioning incompatibilities ripens.   None of this affects builds on Linux, Mac OS, etc.
2025-06-26
For some years now, the Virtual AGC GitHub repository has been configured — thanks, Jim Lawson for setting it up all those years ago! — with the convenient feature that it automatically performed a test rebuild from source, on a Linux platform, of any change to the source code in the repository, thus allowing us to easily reject any commits that would have broken the Virtual AGC build system.  But it turns out that the company providing this nice service, Travis CI, has recently discontinued its free tier for open source projects, and hence lately these automatic builds were no longer being performed.  I was entirely unaware of this.  I've gone back through my communications and find no obvious notification from Travis CI of this discontinuation, though that doesn't necessarily mean I didn't receive any.  (For example, there are several messages informing me of Travis CI's new "usage-based plan" that they tell me could perform wonders for my workflow.  Perhaps these were subtle hints that my free plan had been discontinued?  Well, who know?  And what's the point of grousing about it?)

But what it does mean is that (still more unfortunately) in the last week or two I've been accepted a couple of source-code commits that break the ability to build Virtual AGC from source, under the misplaced confidence that the automatic-build by Travis CI would have detected the particular kinds of problems these pull requests exhibit, and which my visual inspection did not detect.  Yikes!  I've just now fixed those problems, and Virtual AGC does now build from source, but if you've tried to download and build Virtual AGC in the last week or so, you've probably failed.  My apologies!

Finally, to anybody thinking of submitting changes to Virtual AGC — even if you think they're only harmless changes such as program comments — please do run a test build before doing so.  While the Travis CI service is indeed very useful, and to many people undoubtedly very much worth the cost, it doesn't make much sense for projects that give away their code for free, and I'm not going to break open my piggy back to pay for it.  (In case you're wondering, the lowest fixed-price tier is currently $78 per month.  The "usage-based" plan with a $15/month floor would probably  be a lot cheaper, but there's no obvious guarantee of that since the price is not fixed ... and even at the price floor it would still be $180/year more than Virtual AGC's income, which is $0 now and in perpetuity.)
2025-06-24
Added seven more documents today.  Six of these are various missing volumes of the Space Shuttle Systems Handbook, three for Rev E and three for Rev E DCN-6.  All are now in our Shuttle library.  The seventh document is the Mission Operations Directorate (MOD) Drafting Standards.  Mike has categorized the latter as a Shuttle document too, but I've placed it instead in the main document library because it appears to me to be a general-purpose document rather than a Shuttle-specific one.  Still, Mike usually has a more-accurate take on these things than I do, so I may find myself moving it later.  Apparently, Mike found it jammed between pages of the Space Shuttle Systems Handbook, which does speak for the appropriateness of his interpretation, even though I have ignored it for now.
2025-06-09
Seven additional documents relating to different revisions of the Space Shuttle Systems Handbook have been added to the Shuttle Library.  These have all filtered through Mike's hands before showing up on my desk, though most of the documents in today's batch were actually provided by Dak4482.  (To whom, many thanks!)  Here's Mike's synopsis:
Rev D DCN-2 is our first that has AP-101B pages instead of AP-101S, and Rev F is now our "newest" revision.
  • Space Shuttle Systems Handbook, Rev D, DCN-2, Volume 1
  • Space Shuttle Systems Handbook, Rev D, DCN-2, Volume 2
  • Space Shuttle Systems Handbook, Rev F, DCN-3, Volume 1
  • Space Shuttle Systems Handbook, Rev F, DCN-3, Volume 2
  • Space Shuttle Systems Handbook, Rev F, DCN-3, Volume 3
  • Space Shuttle Systems Handbook, Rev F, DCN-4, all volumes, change pages only
  • Space Shuttle Systems Handbook, Rev F, DCN-5, all volumes, change pages only
Recall that "DCN" is a "document change notice".  Regarding "AP-101B" versus "AP-101S", recall that the general purpose computer (GPC) used as a flight computer in the Space Shuttle was IBM FSD model AP-101B for earlier Shuttle flights, but model AP-101S for later Shuttle flights.  At present, we have essentially no surviving documentation for the AP-101B.  In this batch of documents, though, we do have a little bit.  (For anybody interested in exploring the issue themselves, I'd offer the marginally-helpful hint to start with drawing numbers 8.12 and 8.13 for the AP-101S, but 8.3 and 8.4 for the AP-101B.  Those may be hard to find with a text search, but searching for the words "GENERAL" and/or "CPU" may help.)
2025-05-20
Added a new document to the main library and two documents — well, two volumes comprising a single larger document — to the Shuttle library.  Here's Mike's synopsis, with some editorializing by me:
  • Volumes I and II of the Space Shuttle Systems Handbook, Rev D, DCN-4, change pages only. This predates it being split into three volumes, so it should be all of the changed pages for DCN-4. ["DCN" stands for Document Change Notice.  Although, alas, since we don't have DCN-3, we cannot actually reconstruct the entirety of DCN-4 from these changes alone.  Someday, perhaps!  DCN-6, on the other hand, is already in the library.]
  • The LM-1 Data Book, which is a little reference booklet that contains useful information about Apollo 5 plans, telemetry, onboard sequences, software, and procedures.  [Don't be fooled assuming these are yet more reference cards.  This "little booklet" is >100 regular (letter or A4 size) pages long.]
2025-05-14
Mike has sent over three documents for the library.
2025-05-08
Embarrassingly, I've found (and of course fixed) a bug in the "Playing With Luminary" section of the main page (an extra ENTR in step 3) that renders the instructions unusable.  I hate to think how many years that error has been there.  I only discovered it myself because Gavin Eadie has notified me that there are updates to his ApoDisKey program (i.e., his DSKY simulator for Mac OS) related to improvements for the display of digits, and I happened to try and use Playing With Luminary to check out the improvements.  I guess it just goes to show that life is not merely an unbroken climb to greater heights.  As if we didn't already know it!  Or, as Chuckles the Clown reminds us, it's "a little song, a little dance, a little seltzer down the pants."
2025-05-04
Mike Stewart has sent over a small batch of MIT/IL documents for posting to the library.  Here's his summary of them:
  • E-1973, Statistical Estimation in Inertial Navigation Systems
  • E-1942, Command Angle Torquing of Gyros in the Apollo Guidance and Navigation System
  • R-532, Volume I of II, Reentry Guidance for Apollo

Chapter 6 of the final document, he points out, "contains an actual code listing for the Block I reentry guidance as it appeared sometime between Corona and Solarium".  Specifically, that's an (almost?) complete listing of the particular modules RE-ENTRY_PROGRAM.agc and AVERAGE_G_INTEGRATOR.agc, along with a small excerpt from POWERED_FLIGHT_SUBROUTINES.agc comprising around 1500 lines of code altogether.  That it's a missing link between Corona and Solarium is merely an inference, however, since there's no mention of either program in the document.  On other hand, the notion is supported by the date of the document and by inspection of the code, or at least by the superficial inspection I've been able to make so far.  And of course, Mike is seldom wrong.  Personally, I've had to cut short my own inspection of it, because comparing the various programs is rather addictive, and I want to move on to other things this morning.    As you may recall, though, while we have an Apollo-era print of the Solarium 55 source code, we have a "mere" reconstruction the Corona 261 source code ... a reconstruction known to be 100% correct in the octal sense, but which may err in some respects in terms of things like program comments or symbolic names.  So it's possible that "missing link" software could help eliminate some of those errors (if there are any) in the reconstructed Corona 261 source code.  I'll keep my fingers crossed.  If there are any developments on that effort, you can read about the progress here, though obviously once that work is complete, the changes are extremely likely to appear in the reconstructed Corona 261 source code within the repository.

2025-04-30
Regarding the updates to the yaTelemetry program mentioned a few weeks ago, they've been extended so that yaTelemetry now supports every available AGC program that emits telemetry, not just the later ones that were flown on manned missions.  Getting that support in place proved to be quite daunting, since by my count a total of 4 (or 5, depending on how you look at it) different communication protocols were used over the years to emit that down-telemetry, and I ended up having to reverse-engineer and implement all of them ... not to mention, of course, that even where the same protocol was used, different AGC software versions still output different items on the downlists.  Well, I won't belabor that any further, other than to say that it was a lot of work!   As it happens, only a few of the available AGC software versions don't emit telemetry, of which the primary example is RETREAD.  Practically everything else (SUNRISE, CORONA, SOLARIUM, SUNDIAL, AURORA, SUNSPOT, SUNDANCE, and so on) do emit telemetry, and now you can look at it to your heart's content ... which admittedly, may be not too much.  But I like it.
2025-04-12
Added a crucial warning in the write-up of the AGC program DAP Aurora 12 on our Luminary page, providing a trick that's necessary for running that program in the AGC emulator.  As usual, thanks to Mike Stewart for the info!  He provided the info 6 years ago, but it went right over my head at the time.  I only discovered it today because I was checking out the telemetry DAP Aurora 12 emits ... and there wasn't any, because the darned thing had frozen up.  Which is what the 6-years-belated trick documented today works around.  Head slap!
2025-04-09
A little over two months ago, Gavin Eadie (thanks, Gavin!) came to me with an observation that one of the data values displayed by the yaTelemetry program, DSPTAB, was misspelled as DSPTB.  Recall that in the suite of Apollo simulation software provided by Virtual AGC, yaAGC is the emulator for the Apollo Guidance Computer's CPU, while yaTelemetry is a program which can optionally be run to display the telemetry that yaAGC emits while running ... which of course, is the same telemetry data that the original AGC also would have emitted, and which would have been viewed in mission control on the ground.  In our subsequent discussion of this tiny issue, it developed that it was really a subjective matter as to whether what Gavin had observed was a bug, or whether it was simply a design choice on my part.  However, Gavin's observation was the thread that unrolled the entire garment, the straw that broke the camel's back, the tiny mustard seed falling upon a barren place, because it quickly became apparent that there were much bigger problems in yaTelemetry than just this little thing.  Two big problems, in fact:
  1. In the telemetry being displayed, yaTelemetry understood and accounted for the difference between Command Module telemetry and Lunar Module telemetry, but it ... well, I ... had completely overlooked the fact that there was a difference in the telemetry from one AGC software version to the next!  For example, Apollo 15 telemetry differs from Apollo 14 telemetry.  Slightly, admittedly, but significantly all the same.  And that differs from Apollo 13, which differs (even more slightly) form Apollo 12, which differs from Apollo 11, and so on.  Apollo 9 Lunar Module telemetry is almost entirely different from everything else!  And Zerlina?  Forget about it!  As an engineering version of the software whose telemetry was presumably never debugged, Zerlina has portions of the telemetry that break every rule.  Indeed, in my simple-minded implementation of yaTelemetry, practically the only telemetry it possibly got right were the Apollo 8/9 Command Module and the Apollo 13 Lunar Module.
  2. Even assuming that yaTelemetry had gotten it right, though, the telemetry values it displayed were essentially useless.  Why?  Well, suppose you see something like this:  "... NEGTORKU=+0   POSTORKV=+0   RLS+2=0   DAPBOOLS=21316  ...".  Do you even know what NEGTORKU is?  What's the significance of it being +0.  Or RLS+2?  Or DAPBOOLS?  Because I sure don't!  The only way to find that stuff out is to open up our document library and look at Section 2 ("Data Links") of the Guidance System Operations Plan document.  And you know what?  We don't have a copy of that for Apollo 11.  Or Apollo 10.  Or Apollo 12.  We only have a handful of GSOP Sections 2, including the Apollo 8/9 Command Module and the Apollo 13 Lunar Module, which is probably why yaTelemetry got those particular ones correct in the first place.

So  the last couple of months have been a real grind in fixing up yaTelemetry!  Gavin and I have worked closely together to bring this about.  If you were to update your local copy of Virtual AGC today, you'd find that yaTelemetry now displays the correct telemetry for all AGC software versions it supports, namely SUNDANCE, all versions of LUMINARY, all versions of COLOSSUS/COMANCHE/ARTEMIS, SKYLARK, and ZERLINA.  You'd also find that it now has hopefully-easy-to-use documentation that covers what each telemetered item for each AGC software version is.  Each of these two improvements was individually quite hard to implement.  For example, I'd invite you to consider that yaTelemetry is offering to provide documentation for many AGC software versions for which the official documentation is absent entirely.  I won't claim that the new yaTelemetry is perfect, but I'm quite pleased with the improvements.

Check out the write-up here.

Of course, I'm sure with this extensive a change that bugs will turn up that need to be addressed.  On the other hand, given that approximately a dozen years passed between the time yaTelemetry was first released and the first complaint about it, perhaps there won't be any reported bugs for another dozen years.  Also among the to-do's, which I've not yet begun, there will be a separate web-page write-up describing the implementation of these features in yaTelemetry.  Though not of interest to most (any?) of you, that'll be handy so as not to get caught flat-footed the next time (fingers crossed!) that we acquire source code for a missing AGC software version.  Also, there's the entirely separate issue of Block I style telemetry, which yaTelemetry doesn't support at all, but which it would be nice to support someday so that we could use it with missions like Apollo 4, 5, and 6; or even Apollo 1, if we ever get the AGC software for it.  But someday is not today.

2025-04-05
12 new documents posted to the library, mostly but not entirely related to the Saturn's Instrumentation Unit (IU).  Here's Mike's summary of them:
  • Saturn IB/V Instrument Unit Technical Manual, Environmental Control System Description
  • Launch Information, Instrument Unit S-IU-201
  • S-IU-502 Status at Completion of Modifications and Systems Checkout Retest
  • IU-501 Photographs Locations 1-24
  • IU-503 Photographs Locations 1-24
  • IU-504 Photographs Locations 1-24
  • IU-507 Photographs Locations 1-24
  • TCP-IV-26163 GSCU Preventive Maintenance
  • TCP-V-36048 Upper Protective Ring, Guide Pin Bracket, and IU Protective Cover Installation and Removal
  • TCP-IV-24077 IU Preparation for Erection
  • TCP-V-20030 Spacecraft/Launch Vehicle Mate & Demate
  • The Delco booklet for Apollo 14
2025-03-04
Nine volumes of Saturn V countdown procedures were added to the library, pertaining to Apollo 12 through 15 launches.
2025-02-28
Added the ALSEP (Apollo Lunar Surface Experiments Package) console handbook for Apollo 12-17 to the library.
2025-02-23
A couple of days ago, I mentioned that in Windows, our Verilog-based simulation framework of the AGC electronics wasn't capable of displaying the decoded AGC instructions nor the addresses at which those instructions resided.  Which admittedly, is an "enhanced" feature of our Verilog simulation framework that is a nice afterthought but not strictly necessary for profitably using the framework.  Still, it was annoying to me.  Fortunately, one of the developers of the GTKWave signal-trace viewer we use to display the results of the electrical simulations suggested a workaround, so the simulations now seem to be fully working in Windows in today's version of the "schematics" branch of the software repository, and hence fully working on the big-three operating systems.  (Thanks, Tony Bybell, though I'm sure you'll never see this!)

Although I failed to mention it a couple of days ago, I should have specified that only digital simulations of the Block II AGC electronics work.  Simulation of Block I AGC electronics is very far from working, not for any fundamental reason, but just because of the very large number of pesky little differences in detail from Block II that I have neither the time or inclination to deal with.  Indeed, it's very possible that I'll never get around to it.  But nobody has ever communicated to me that they're using the Block II simulations anyway, or indeed even the transcribed AGC schematics.  In other words, the electronics simulation (and transcription of electrical schematics) has all of the hallmarks of being just a vanity project for me, in which case the lack of simulation for Block I AGC electronics is hardly likely to be much loss to anybody.  Too bad, though, since it's pretty nifty!  A great idea of Mike's that I've piggy-backed off of, but would never have thought of myself.  Fortunately, I have plenty of vanity to spare, so I can waste some on a vanity project without having a shortage afterward.
2025-02-22
Clarified the SPOOF_SC option for the simulateAGC script on the Verilog page.
2025-02-21
Although it has taken a seemingly-infinite amount of time (and beyond!), digital simulations of the AGC electronics via conversion into Verilog that were broken by changes in the KiCad EDA file format are once again working, though now with various improvements:
  • Automatic decoding of AGC instructions and addresses (sort of) directly within the electrical waveform viewer.  Though I'd note that on Windows this particular enhancement doesn't work for me, and a fix for that is out of my hands.
  • Automated simulation of a full AGC not just in Linux but also (new!) in Mac OS and Windows, via a new shell/batch script called simulateAGC.
  • Automated simulation of individual AGC logic modules (or circuits based on them), via a shell/batch script called simulateModuleII.

I've also verified both this feature and the ability to update it in the Virtual AGC VM.  In other words, the VM can be updated via its desktop icon to add Verilog simulation capability.  The download page and Verilog page have been updated with all relevant info, and the former contents of the Verilog page — i.e., the page covering electronic simulations based on the now-obsoleted KiCad EDA file format — is permanently preserved as a separate page with updates to reflect the new reality.

Alas, it still doesn't handle simulation of Block I electronics.

2025-02-14
Today we have the so-called Apollo 13 Delco book to add to our now extensive collection of Delco books for other missions in the library.  Note that pages HW-43 and HW-44 are duplicated, whereas pages HW-45 and HW-46 are missing; that's a problem in the book itself, not a mistake in the scanning process.  It appears to me that those missing pages correspond to pages HW-43/44 in the Apollo 15 Delco book, so they're not gone entirely.  I hope.
2025-02-12
Just over a month ago, I pointed out that while bringing the Virtual AGC VM up-to-date I had encountered the problem that the KiCad EDA system into which AGC/DSKY schematics are transcribed had evolved to the point that Verilog-based electrical simulations of the AGC no longer worked with current versions of KiCad, while the older version of KiCad could no longer be installed in the VM.  Oh, no!  Fortunately, this change didn't affect the simple act of viewing or working with the electrical schematics in any meaningful way, but it basically broke the ability to perform the digital simulations of the AGC electronics.  This is issue #1239 in the problem-reporting system, for anybody who cares to follow it.

I've spent most of the intervening time working on getting those digital simulations of the AGC electronics working again, so that I can finally tuck the VM cozily into bed and wish it a good night.  At the same time, I've essentially fully replaced the commentary on performing the simulations, since the old commentary was not only out-of-date, but also very poorly written and confusing.  Of course, being me, and being pretty complex anyway, it's still poorly written and confusing.  But seemingly a lot less so.

Alas, the software updates have proven quite challenging, so that while I can perform small simulations such as for a single AGC logic module (like module A1, the SCALER), full-AGC simulations still elude me.  Indeed, the software updates have proven so challenging that I need to let the entire problem stew for a little while and move on to other things, which means that I have no good sense of when those updates may eventually be complete. 

As a stopgap measure, I've added instructions for the temporary workaround of using the obsoleted KiCad v.5 electrical schematics to form the digital simulations.  It's very unsatisfactory, but it's better than leaving it in a completely non-functional state.
2025-02-11
On the Luminary page, I note that the entry for the ZERLINA 56 engineering version of the AGC software refers to a 1971 digital simulation of a lunar landing using ZERLINA, but doesn't actually provide any link to that simulation.  Ouch!  I've fixed that.

In other news, regarding my continued fussing over dangers to the National Archives, I was sent this link to an article in Rolling Stone. Unfortunately, it seems to be subscriber-only, so I haven't read it myself, although the title probably conveys most of what you'd need to know.
2025-02-09
More documents from Mike for the library today; here are his comments:
  • A really good PGNCS training book from North American Rockwell, in two parts.
    • Part I covers the Inertial and Optics subsystems
    • Part II is all about the Computer Subsystem (i.e., the AGC)
  • The Charles Stark Draper Laboratory, a marketing brochure. Of all of the brochures I've scanned, this one has by far the most marketing mumbo-jumbo. It also has a bunch of nice color pictures.

Separately, I note from news reports that the Archivist of the United States — i.e., the head of the U.S. National Archives (NARA) — has been summarily dismissed by the President. No reason was offered for this action.  As to whether this relates at all to my several comments a couple of weeks ago about the future of NARA, all I can say is that it doesn't fill one with confidence.

2025-02-05
Another load of documents for the library today, this time all pertaining to the CSM.  Here is Mike's summary:
  • FO-K-3114-SC009- Spacecraft Prelaunch Test Procedure, Command Module Cleaning. This contains some of my favorite steps I've seen in an official Apollo procedure:
1.2	CLEANING OF C/M
1.2.1 VACUUM C/M.
1.2.2 REMOVE VACUUMING EQUIPMENT.
  • Apollo CSM "J" Series Mission Experiments
  • A lone foldout showing the Block I CSM panel layouts
  • Apollo 15 Headquarters Flight Readiness Review, Part I, Mission Summary Command and Service Module
  • Apollo Block II Wire and Wire Bundle Current Rating
  • A small pile of North American Aviation "Certification Test Requirements" sheets
  • CSM/LM Spacecraft Operational Data Book, Volume I, CSM Data Book, Part I, Constraints and Performance, partial copy. Even though we have a "full" copy of this in the library already, this one is still interesting in that it has some pages from later amendments than our existing scan.
  • APC-118 - Apollo Training - Apollo Spacecraft & Systems Familiarization,  February  24, 1967
  • APC-106 & APC-124 - Apollo Training - Apollo Spacecraft & Systems Familiarization,  April 1, 1966
  • Apollo Training - Telecommunication System Block II, 8 April 1968
  • Apollo Training - Electrical Power Subsystem Block II CSM, 1 August 1967
  • Apollo Training - Electrical Power Subsystem, Feb 22, 1967
  • Apollo Training - Apollo Operations Handbook - CSM Block II, Preliminary - Subsection 2.6 Electrical Power System, 28 September 1967
  • Apollo Training - Apollo Operations Handbook - CSM Block II, Preliminary - Subsection 2.6 Electrical Power System, 26 December 1967
  • Apollo Training - Apollo Operations Handbook - CSM Block II, Preliminary - Subsection 2.9 Sequential Systems, 29 February 1968
  • Apollo Training - Apollo Operations Handbook - CSM Block II, Preliminary - Subsection 2.9 Sequential Systems, Supplement to  29 February 1968
  • Apollo Training - Block II CSM Propulsion Subsystem, 19 April 1968. This is a particularly handy study guide because it outlines in great detail the propulsion-related differences between CSM-101, CSM-103, CSM-104, and CSM-106+. It also contains four particularly nice foldouts: original main display console layout engineering drawings from North American. These felt significant enough to also present as standalone documents:
    • V36-976018, Design Layout - Main Display Console, Command Module 101
    • V36-976020, Design Layout - Main Display Console, Command Module 103
    • V36-976021, Design Layout - Main Display Console, Command Module 104
    • V36-976024, Design Layout - Main Display Console, Command Module 106
2025-02-04
Mike has sent in a load of Shuttle documents for the library today:
  • Integrated System Schematic, Electrical Power Distribution and Control (EPD&C) Orbiter Vehicles — 099, 103, & 104, revision E0 A06 change pages only
  • The Programming Language HAL - A Specification, draft version. We currently have the released version in the library.
  • Final Report, Standard Interface Definition for Avionics Data Bus Systems
  • Program Acquisition Plans, Space Shuttle Program Phase B Systems Study, Final Report, Part III-5: Test
  • Advanced Software Techniques for Data Management Systems.  All 3 volumes were already in the library, but here are scans from different physical copies of a couple of them:
    • Volume I: Study of Software Aspects of the Phase B Space Shuttle Avionics System
    • Volume II: Space Shuttle Flight Executive System: Functional Design
  • Task 28-S, Volume IV, Shuttle Avionics Computer System Studies
2025-02-03
On the download page, added the MD5 checksum, along with instructions for how to use it, to the download for the Virtual AGC VM.
2025-01-31
Today's theme is Saturn! Still with a sprinkling of Charlie Bell's papers, but also from a variety of other sources.
  • Saturn V LVGSE Integrated Systems Orientation, Volume I
  • Saturn V Operating System Redesign (note that this is referring to the RCA-110 on the ground, not the LVDC)
  • Firing Equipment Cables and Cable Acessories for Ground Support Equipment, Saturn Vehicles (truly everything you could want to know about wiring harnesses)
  • A chart containing dates of significant Saturn milestones
  • Saturn V Flight Evaluation Trend Report AS-501 through 508
  • Story of the Uprated Saturn I (Saturn I-B)
  • Saturn/Apollo Launch Operations Test Procedure - Telemetry Checkout Equipment Test and Calibration
  • Console, Common Bulkhead Vacuum Monitoring Maintenance and Calibration Procedure
  • A packet about Saturn ground computer systems
  • Saturn/Apollo Frequency Plan - Instrumentation & Communications Interfaces
  • Study Guide, OC 503 GAC, LC-39 SLA Emergency Egress System
  • Fault Isolation Guide, Saturn S-IVB Stage
  • Saturn V System Definition, Volumes I and II
2025-01-30
And here's Instrument Unit, part 2! All from Charlie Bell's papers.
  • Technical Manual, S-IVB Forward/Instrument Unit Umbilical Assembly, Saturn V, May 1969 change pages only
  • Technical Manual, Saturn IB/V Instrument Unit Command Decoder. This is the full manual, but it is a scan of a mimeograph of a taped-together copy of the document, so quality leaves a bit to be desired.
  • Technical Manual, Command Decoder, August 1969 change pages only
  • Technical Manual, Flight Control Computer (500 Series Vehicles), August 1968 change pages only
  • Technical Manual, Measuring and Telemetry System Description, April 1969 change pages only
  • Saturn IB/V Instrument Unit System Description and Component Data, June 1967 change pages only
  • Saturn IB/V Instrument Unit System Description and Component Data, December 1967 change pages only
  • Measuring and Telemetry Information Summary for CDDT and LCD
  • A set of excerpts from various IU manuals, which Charlie kept in an unlabeled black binder. Some are mostly complete, while some only have a couple of pages.
    • Saturn IB Instrumentation Systems Description, excerpts
    • Maintenance and Instruction Manual, Digital Data Acquisition Subsystem / Computer Interface Unit Model 501, excerpts
    • Maintenance and Instruction Manual, Remote Digital Multiplexer Assy Model 410, excerpts
    • Maintenance and Instruction Manual for Model B1 Telemetry Oscillator Assembly, excerpts
    • Maintenance and Instruction Manual for Telemetry Calibrator Power and Control Assembly, excerpts
    • Maintenance and Instruction Manual for Model II Telemetry Calibrator, excerpts
    • Maintenance and Instruction Manual for Model II Radio Frequency Assembly, excerpts
  • IU Telemetry Meas. No. Listing, IU 204L thru EO 71
  • IU Telemetry Meas. No. Listing, IU 204 thru EO 71, Edition 4
2025-01-29
Today's update is accompanied by a story, which I'll relate verbatim as Mike gave it to me:
"Today's theme is the Instrument Unit, part 1. The majority of this stuff came from a big pile of Charlie Bell's working papers that I got my hands on last year. Charlie was an IBM engineer who worked on the command and telemetry systems for the Instrument Unit — and especially the associated ground support equipment — during the Apollo program, and then went on to work at KSC. While there he became dismayed at how much historical stuff was being scrapped and endeavored to buy as much as he could — which turned out to be a truly incredible amount."
Of course, the nature of Charlie's cache insures that a lot of it doesn't really concern us here, as well as not necessarily being of the best quality visually.  But we're hardly in a position to complain, and can only be grateful that it exists at all.

Why am I telling you all of this?  Charlie's story will strike a chord in anybody engaged in preserving historical space-program material.  I refer to the extreme effort (not to mentioned expense) required, the hit-and-miss nature of the material you can get, and the fact that no matter how well you succeed — and make no mistake, I'm very pleased with how well the Virtual AGC Project has eventually succeeded —, it's still a drop in the bucket compared to the material that used to exist.  But mostly, that dismay that Charlie felt in seeing this important material willfully being thrown away in great quantities is always present in us as well.  Sigh!  Well done, Charlie.

With all that said, pointlessly unless we can arrange a DeLorean to take us back in time with a list of contacts and vast quantities of ~1970 dollars to somehow fix it, here's Mike summary of today's contribution to the library:
  • Rework and Install Flight Control Computer S/N 112V, 50Z35300-017 (assessment and final copies), rework instructions for the SA-514 FCC
  • A set of Manufacturing Engineering List Change Memorandums
    • Electrical No. 1 for the SA-10 IU
    • Electrical No. 2 for the SA-10 IU
    • Electrical No. 2 for the SA-500FS IU
  • A set of Computer Interface Unit (CIU) schematics, waveforms, and notes
  • A complete set of pinouts for all external and internal CIU connectors
  • A set of drawings/schematics for the CIU test box
  • A memo concerning the shipment of S-IU-204 to KSC
  • A set of LVDA interface drawings
  • The Telemetry Calibration Program TT01 Sequence — whatever that is!
  • A set of PCM/DDAS receiver diagrams
  • Calibration Error Elimination Test, AS-206
  • Design and Performance for Unit Logic Device Types 322, 323, 324, Discrete Input Buffer (DIB) — this could be helpful when studying the ULDs in the LVDC and LVDA
  • Schematics and descriptions of the clock circuits in the Mod 270 Multiplexer
  • A set of org charts for the KSC branch of IBM FSD.  [Note, unsurprisingly, that a few of the names on this org chart show up in discussions both of the Apollo LVDC computer and of the Gemini OBC computer.]
2025-01-28
A couple of things today:
  • Recently, a chap named Gavin Eadie felt like playing around with the Swift programming language in Mac OS, and decided to do so by creating a new simulated-DSKY program (ApoDisKey) that would more-closely reflect the visual appearance of an actual DSKY than my own simulated-DSKY program (yaDSKY2) that's provided with Virtual AGC.  Gavin's alternative to yaDSKY2 has now had its first release.  If you're running any recent version of Mac OS, it's dead simple to install — certainly as compared to the steps needed to install the rest of Virtual AGC! —, and you might like to check it out.  The VirtualAGC GUI has had support for ApoDisKey for some time, even though there had been no release yet and I hadn't written up any explanation for it.  But now I have written up an extensive explanation on our download page.  The bad news for the rest of us is that while Swift purports to support both Linux and Windows (in addition to Mac OS, iOS, and so on), as I understand it the features needed by ApoDisKey are very closely tied to Apple's system libraries, so there's no chance whatever of porting ApoDisKey outside of the Appleverse.
  • Mike has sent along our daily fix — again, be warned that you'll soon have to go cold turkey! — of nine documents for the library.  Today, again, there's no theme to them:
  • Sundisk Memo 1-68: Incorrect Extrapolation of W Matrix
  • A marketing brochure for the LM Alignment Optical Telescope
  • From Simple Quadrant to Space Sextant, an article detailing the evolution of the sextant, culminating in the Apollo PGNCS optics
  • Repository Index of Saturn and Apollo Engineering Reports and Procedures, which seems to be the MSFC equivalent of the AETI
  • Apollo Support Equipment Maintenance - Apollo Television Bench Maintenance Equipment Model C14-175
  • March 1966 change pages for the same
  • A marketing brochure for ACE-S/C, with lots of good-quality colorful pictures
  • KSC Procedure, Electrical Ground Support Equipment Fabrication
  • Apollo Support Equipment Maintenance Handbook, Carry-On PCM System Model C14-210(-0003)

Finally, a few days ago I geeked out here about my theory — it is mine, and belongs to me! — that DOGE might end up wanting to eliminate the National Archives.  My understanding is that in the brief interval since I posted that theory, DOGE's mandate has morphed from wholesale elimination of perceived government waste to instead increasing government efficiency by digitizing its operations.  I don't see that as being a threat to NARA.  So ... whew!

2025-01-27
11 new documents today, though with no particular theme.  By the way, in case you've been thinking that this recent document smörgåsbord can go on forever, alas no!  Mike is nearing the end of the document backlog, and will soon be caught up.  The salad days, so to speak, will soon be over.  Of course, that doesn't mean that every surviving document in the world will have been posted.  There's plenty out there, hidden in dark closets, and Mike seems to be some kind of magnet for them.  So buck up your attitude, mister!  Or missus.  Or other.  The best days may yet be ahead!  Just not imminently.  As for today's stash, however, here's Mike's summing up:
  • A document labeled "Apollo 6 Quick Reference" on a sticker, but with no actual title printed within. [There's actually a lot inside of it that's not directly related to Apollo 6, including detailed technical data on Apollo 4 and 5, as well as answers to apparently-random questions by the Press.]
  • Apollo 5 Mission Public Information
  • Apollo 5 Public Affairs Plan
  • Apollo 5 Mission Requirements
  • RTCC Differential Correction Process
  • Project Gemini Familiarization Manual, Volume II, Rendezvous and Docking Configurations (original release, over a year older than the version currently in the library)
  • MSFN Network Operations Procedures for UHF Command System
  • LC-37 OTV Camera Locations
  • Introduction to Guidance/Navigation by AC Spark Plug (this has some pretty fun illustrations)
  • SA-204/LM-1 Data Evaluation Guide (rev 2 changes only)
  • Skylab Familiarization

The "Introduction to Guidance/Navigation" book has the additional fun feature that it's not really a book at all, but instead is intended to be used with something called an "ACceler-aide teaching machine".  Rather than a book, think of it like a very low-tech game cartridge that just happens to look like a book.  Thus it doesn't have "pages", but instead has "frames", and is full of instructions like TURN SELECTOR TO POSITION 3; its author, we're told, didn't write the book, but instead "programmed" it; text and quizzes and answer keys are interwoven in a manner that the machine (I would suppose) untangles for the user.  Searches have turned up no information whatsoever about the ACceler-aide, but from the name, one can only assume that it was something developed by AC Spark Plug itself.  Its name alone impresses:  Presumably it's an "aide" developed by "AC" that "accelerates" your learning!  That'll probably haunt my dreams tonight.  Searches do turn up various books or papers from the 1960's about teaching machines in general, though they're behind paywalls that I have no inclination to spent my money to breach, so I don't know what those books and paper say.  At any rate, the "teaching machine" is a concept that doesn't seem to have caught on like wildfire back in those days.  People who held the purse-strings seem to have stayed away from it in droves.  Of course, we have teaching machines today, though in the form of tablets and educational software in general — or even this very website —, so the wheel ends up turning full circle.  Fortunately, the book can be used without the machine, and indeed gives some instructions for doing so.

Someone should develop an ACceler-aide simulator so that we can read the book in its full, original glory!

2025-01-26
17 new documents today, all Skylab themed.  Most relate to experiments and investigations performed aboard Skylab, and hence not very closely related to our normal "astrogational" themes, but that's life in the space-program digital-archaeology biz! 

I've noticed, by the way, that many Skylab-related documents haven't really been well-categorized in our document library.  As the library has increased in size, finding the Skylab documents in it has become more of a chore.  Part of the problem is that many of our Skylab documents don't fall into clear-cut useful categories that our Apollo documents do, so the documents don't appear in any of the topic-specific subsections of the library and simply end up in the huge "Everything" section at the end ... where they're swamped by the much larger number of Apollo documents.  While I don't have a good solution for this irritation at the moment, I've worked around it a little bit by creating a new "Everything Skylab" subsection in which all or most Skylab documents should appear.  Certainly not ideal, but better than nothing, I hope!
2025-01-24
  • Today we have twelve more short documents, all related to Apollo 17, found stuffed into (I guess) the Apollo 17 LM Console Handbook we added to the library back in August.  Especially interesting to me are screenshots of mission-control consoles.  Would that I had had those, back in those ancient days when my intention was that the telemetry monitor program (yaTelemetry) used in AGC simulations would display the telemetry in the same format as it was seen in mission control!  But alas, it was not to be.  Instead, yaTelemetry nowadays just uses a free-form display of the downlinked data, and I've abandoned my dreams of olde.
  • Added a challenge to the main page that might be an interesting class project for some computer-programming enthusiast who's still in school.
2025-01-23
Twelve more documents today, with the theme of the day being "procedures".  Mike's descriptions:
  1. Spacecraft Operations for Space Vehicle Launch Countdown/Countdown Demonstration for SC-017 (Apollo 4). Particularly notable for Virtual AGC, this procedure contains all of the expected bugger words for the bank sum check test (on pdf page 340, and again on pdf page 372). As expected, these match Solarium 55. If only we could find this document for AS-202 or Apollo 1!
  2. Apollo 10 Postretrieval Procedures, as-run. This document contains all of the procedures run after recovering the Apollo 10 capsule, and is heavily annotated by the recovery crew.
  3. Launch Vehicle Operations for Support of Space Vehicle Countdown Demonstration Test and Launch Countdown, Volume III of III (Apollo 14) -- all about scrubs and scrub turnarounds.
  4. Launch Vehicle Operations for Support of Space Vehicle Countdown Demonstration Test and Launch Countdown, Volume II (ASTP), rev 027 change pages only
  5. Apollo 16 Flight Plan, Final. This is an older revision than the one already in the library. But oddly it contains the instructions for the Change C pen-and-ink changes, which could be helpful if the handwriting in the existing scan is ever hard to read.
  6. Apollo 13 Lunar Surface Procedures, Final, Rev A, change pages only
  7. Apollo 17 LM Timeline, Change C
  8. Apollo 17 LM Timeline, Change D, change pages only
  9. Apollo 17 LM Timeline, Change E, change pages only
  10. Apollo 17 Flight Plan, Final, Change B, changes only
  11. Apollo 17 Flight Plan, Final, section 5 only. While not the full document, this excerpt is interesting because it has handwritten changes/corrections that appear to have been made during the flight.

The twelfth document is from NTRS rather than from Mike, and is not a procedure.  I found Mike's first document above exciting enough to try to find similar documents already online.  There weren't any that I could find, but there was a KSC bibliography listing lots of others, and that bibliography is the twelfth document I'm adding today.  The memory-bank checksums (or "bugger words") Mike mentions are of overwhelming interest in demonstrating the validity of reconstructions of AGC software when the original program listings are absent, or of the accuracy of dumps of AGC physical core-rope memory modules.  So any time we can get a list of bugger words we didn't already know, for some AGC software version or the other, it's a big deal.

  1. A bibliography of documents in the Kennedy Space Center library that its librarians felt (in 1969) might particularly be of general interest.

It just goes to show that any documentation, no matter how peripheral it may seem to the AGC or other spaceborne computers we're concerned with here, may still hold the critical datum we need in unraveling our little mysteries.  So — dare I say it? — if you hear of efforts to cut expenses by eliminating NARA or other archival sources of information about the space program, resist them with all your might rather than shrugging your shoulders indifferently and relishing the few pennies you'll save on tax day if our government records are shredded or hidden in a dark closet by private individuals rather than preserved for us all.  I haven't heard of any such effort in progress, but it doesn't exactly stretch the imagination or credulity, does it?

(Actually, to be accurate, NARA's 2025 budget request is about $481M.  There are about 150M taxpayers in the U.S.  So NARA costs you around $3/year.  I suppose that whether that's "a few pennies" or not is a subjective matter.)

2025-01-22
Nine more documents for the library today, this time all chocked with LEMony goodness.  Here's Mike's summary:
  • Early Manufacturing Plan for the LM
  • A LM Instrumentation study guide (one of the few subsystem study guides we were missing)
  • A couple of LTA-8-related documents:
    • List of OCP start dates, indicating planned start dates for various tests
    • A floor plan of JSC Building 32, where LTA-8 thermal-vacuum testing took place
  • A Grumman specification for RF connectors
  • Sheet 3 of LM drawing LDW340-54050
  • A packet of instrumentation drawings and data for LM-10, which I think largely consists of Systems Handbook excerpts
  • A user's manual for the Lunar Module Simulator
  • A Lunar Module Simulator "Console Directory" which appears to list available telemetry measurements
2025-01-21
Yesterday's departure from it aside, Mike has returned to his recent trend of themed releases as he continues to work through his document backlog with 6 new documents for the Apollo/Gemini library and 1 for the Shuttle library.  Well ... one of those documents contains copyright notices, so while I'm "including" it in the the library, I'm nevertheless withholding it from view until 2061, thus leaving you in suspense for the next 36 years as to which telecommunication devices Collins Radio was manufacturing in 1966!  Don't blame me, blame Disney.  Today's theme:  telecom, mid-1960's-style!
  • A CSM telecommunication systems study guide
  • Two early documents from Radiation Inc. concerning preliminary designs for the Apollo PCM telemetry box
  • A brochure from Collins Radio detailing most components of the Apollo and Gemini telecommunications systems
  • TRW press information for the Space Shuttle communications subsystem
  • A flight control "orientation and indoctrination" book for the Apollo Command Network
  • An S-IC Design Data book section about telecommunications — this contains module-level schematics of the Saturn PCM telemetry box and Mod 270 multiplexer
2025-01-20
9 new documents for the library today — well, new and old —, a mixed bag this time.  Here are Mike's comments:
  • Two Skylab-3 checklists
  • Delco booklets for Apollo 15 and 17
  • Section 4.2 through the end of the OWS Design Data Document for Skylab (sadly the guy I got this from has no idea where everything before section 4.2 went, but he's pretty sure he never had them).
  • Apollo 10 Commentary, which is largely transcripts from the mission
  • Mission J1 G&N Error Analysis
  • Case History of the Apollo Guidance Computer - we already have a scan of this, but it's one of those that was ravaged by OCR text replacement
  • The final report on the assembly and test of five IRIGs with size R-4 ball bearings
2025-01-19
18 additional documents for the library today, all Apollo Soyuz Test Project (ASTP) related.  Here's Mike's categorization:
  • The CSM-111 + Docking Module Systems Handbook
  • A set of pages defining AGC erasable memory program ASTP-76
  • A bunch of checklists and revisions thereof
2025-01-18
And eight documents again today!  Here's Mike's summary of them, as very lightly edited:
  • A Yul System Program Sheet, onto which AGC developers would write out code changes before they were punched onto cards
  • A small set of reference cards meant for use with Sundial D
  • A later Apollo JDC Index than the one we currently have in the library
  • A collection of Systems Support Training reference cards from Raytheon (from the same group as this earlier document we had), including:
    • A booklet showing all of the AGC control pulses
    • A booklet showing standard circuits of the AGC Buffer Box and Program Analyzer Console
    • Two versions of a reference card showing how AGC banks are mapped into rope strand select signals
    • A pair of cards showing the punch tape format for the KSTART and Computer Test Set
SUNDIAL, you may recall, was Block II AGC software used in Command Module system tests.  We unfortunately do not have a copy of SUNDIAL D, but we do have a copy of the next-later release, SUNDIAL E.  Among the interesting information included in the SUNDIAL D "reference cards" mentioned above is SUNDIAL D's downlink list.

I've been forced to be somewhat creative in inventing titles and dates for these documents, since only one of them is dated and most of them have no titles.  And in one case, I've claimed that the "author" of the document was really just the guy who likely assembled the bits and pieces of it into one place.  Well, too bad!   It is what it is.  Or course, if anybody has greater insight than I do — which perhaps would not be that difficult —, send me whatever corrections seem appropriate.

2025-01-17
Mike has sent eight new documents for inclusion in the library, consisting of 3 Instrumentation Lab documents and 5 sets of reference cards. 
2025-01-13
  • I realize belatedly that I've been handling fixes to Virtual AGC stupidly.  There's a problem-reporting system associated with our GitHub repository, but if someone has directly reported a problem to me I've just tried to handle it directly with them, and if that's successful there's never any problem report generated.  Why that's dumb is that since there's no paper trail on it, there's no good way for anyone to know what problems have been fixed in what revisions of Virtual AGC, or even if they've been fixed at all, and hence no way for them to know if it's worth updating their Virtual AGC installation.  Even I don't know, half of the time.  D'oh!  Please create problem reports, even if you're going to communicate with me directly.  If you don't, then I'll have to do it for you, and I'm really lazy so I don't want to!  For myself, I'll try to make a better effort on this, until it loses its urgency and I forget all about it.
  • I realized this while dealing with problems reported directly to me that the LM_Simulator component of Virtual AGC doesn't work in the latest version of Tcl/Tk, and that Tcl/Tk doesn't work at all in any recent version of Mac OS.  While researching the fixes that had to be made, I realized I had no way to backtrack through earlier versions of Tcl/Tk to see if my fixes would break LM_Simulator in them or not.  It's not the same thing as the problem-reporting issue in Virtual AGC, of course, but it pointed a big "j'excuse!" finger directly at me anyway.  Speaking of which, issues #1234 and #1235 (the Tcl/Tk/Mac OS problems just mentioned) have been dealt with, and you should check them out if you've experienced either problem.  Not only that, but it turns out that up to now the installation instructions for Windows haven't mentioned that Tcl/Tk needs to be installed (issue #1237).  So that's fixed too.
  • Some corrections were made (issue #1238) in the drawing-tree drilldown for AGC model 1003565 and to the guidance-system drilldowns containing it (principally, mission AS-202).
  • Okay, enough of the meae culpae!  Mike Stewart has sent over a few new documents for the library, all of them Pratt&Whitney reports on Apollo CSM fuel cells.

Aside:  I don't know if that's correct Latin or not, since I've forgotten all the Latin I learned 50 years ago, but it's more fun than "mea culpas" as most google hits recommend.  See here.  I think "mea culpas" actually makes the most sense, though, on the notion that "mea culpa", in spite of its appearance and history, to English speakers is nowadays a single English word rather than two Latin words.    As for the French, I have even less excuse for "j'excuse!" since I don't recollect ever learning any French at all.  But I digress.

Don't worry, these change-logs probably won't be packed with issues corrected in the software the way today's post is.  After all, if you're interested you can look at the issue-tracking system yourself.  I'm just excited about the notion right now, so I can't help it.
2025-01-12
The tic-tac-toe game mentioned yesterday has now been integrated into the VirtualAGC GUI program, and is one of the choices of available mission.  A write-up has also been included in the "Quick Start" section in our website's introductory page where various things that can be done without a learning curve are covered.
2025-01-11
I got a terrific note just now from folks who have created their own apps for the AGC+DSKY.  If my heart hadn't hardened so much over the course of time, I'm sure it would bring a tear to my eye since it's one of the things I always hoped people might do with Virtual AGC.  It has taken a while, but now they have!  I'll just directly quote a portion of the email, lightly edited, rather than summarizing it:
... our little project is wrapping up successfully.  It has been an absolute joy to program on this computer.  We'll be presenting a talk about bare-metal programming of the AGC at next weekend's Vintage Computer Festival here in Switzerland.  I'll send you the video once they post it.



The tic-tac-toe game is fully functional and available here.  The + and - buttons switch between one or two player mode.  The reset button starts a new game. ...  There's also a random die (D6) application in the same directory that serves as a good demo of minimal DSKY I/O, alarm suppression, and random number generation.
I'm sure I'll be writing a lot more about this later, but I thought I'd post about it now just in case anybody is in a position to attend the festival and this might prompt them to do so.
2025-01-10
  • I've noticed that the description on our developer page about how to use the our library functions agc_xxxx() to create your own AGC emulator in place of yaAGC inaccurately describes how the critical function agc_engine() is supposed to be used.  If you actually used my instructions — and somebody was! —, it would have worked but the timing wouldn't have synchronized with real time very well.  That's fixed now.  You may wonder why you'd want to do such a thing anyway!  It's the kind of thing you'd want to do if, for example, you were making a model control panel which embedded an AGC emulation within it rather than as a separate program.
  • Mike has sent over 3 new documents for the library.
  • The page concerning Verilog-based digital simulation of the AGC electronics is undergoing substantial rework due to the issues I mentioned a couple of days ago.  I mention it not to call those changes to your attention — they're not ready yet! — but rather to point out that the page isn't currently fully reliable.  Alas, my workflow doesn't allow me to easily post the changes I mentioned above without posting the incomplete Verilog-page changes as well. 
2025-01-08
Two more documents for the library today from Mike, both interesting, and one them very exciting:
  • "Apollo Soyuz Test Project (ASTP) Manual".  This is one of the series of books in our library, published by Delco Electronics, seemingly one for each mission, that provide elaborate technical summaries of the flight software and hardware subsystems of the CM/LM guidance systems.
  • The LVDC Equation Defining Document (EDD) for AS-501 (i.e., Apollo 4).  What's so exciting about this is that it's the very first Saturn V EDD we've gotten, in contrast to the Saturn IB EDD already in our library.  Apollo 4 was the very first Saturn V mission, so I suppose we can expect that the EDD had a few teething difficulties.  For example, the memo that formally approved this EDD warns us not to take the EDD too literally, because "since [publication], 45 engineering change requests and 49 engineering change proposals have been processed in regard to the 501 flight program".  Still, I'm not going to turn up my nose at it!

There have also been various corrections to the main website page and the download page, thanks to Gavin Eadie.

2025-01-07 The new year is starting out with a flourish if not necessarily a bang.
  • Mike has sent over a few new docs for the main document library and the shuttle library.  Check them out!
  • Having had the chance to look at it in some detail after mostly ignoring it for a long time, I have come to realize that Virtual AGC's installation instructions and graphical-interface applications (such as the simulated DSKY and the telemetry monitor) had rotted somewhat over time.  While still mostly functional, they had nevertheless degraded from "acceptable" to "positively crummy".  This was partially due to neglect on my part.  But it was also partially due to the relentless march of time, over the course of which operating systems had evolved, and software libraries which I had depended upon had been obsoleted and replaced by other versions of those libraries that didn't work quite the same way.  Then too, there was the availability of 4K displays for desktop systems, with the consequence that software not prepared for 4K had acquired very, very tiny user interfaces.  The upshot of all this is that I have spent a fair amount of time revising all of the graphical user interface (GUI) code for Virtual AGC programs, so that these programs now look fine on all of the Linux/Mac/Windows systems to which I have access, with either "normal" or 4K displays.  To support the possibility of high-DPI displays, these programs now all rely upon a new environment variable (AGC_SCALE) which can be assigned a number such as 1.5 or 2.0, the default being 1.0, by which the sizes of all of the Virtual AGC user interfaces are new automatically scaled.  The same scale is applied to all Virtual AGC programs, but doesn't affect any non-Virtual-AGC programs.
  • Another thing is the transcriptions we've provided of AGC/DSKY electrical-schematic drawings into computer-aided design (CAD) files for use in the open-source KiCad EDA system.  When those transcriptions were done back in 2018 or 2019, KiCad v.5 was still a new thing, whereas nowadays KiCad v.8 is current and v.9 is in development ... but the format for the schematic files was 100% changed at v.6.  While the new versions of KiCad can still read my old v.5 transcriptions and convert them to the new format, as always with these things the conversion isn't guaranteed to be 100% perfect.  Mostly; but not quite.  So I've put in quite a bit of work — recall, or be informed, that there are about 140 transcribed drawings, most of them with multiple sheets — doing the manual adjustments to make sure those conversions are indeed exactly right after all!
  • And then there's our Verilog-based digital simulation of the AGC electronics, based on the CAD transcriptions I just mentioned.  Well, it turns out that the Python scripts used to process the schematics in order to produce the needed Verilog source-code files don't understand the new format of KiCad's schematic files!  So Verilog simulations will be on hold for a while until I fix up those Python scripts.  Hopefully that'll be in the not-too-distant future, but I haven't started on it yet.
  • And speaking of Python scripts, most of our Python scripts are written for Python 3, but a few older scripts based on Python 2 have persisted, since it has always been possible to install both Python 3 and Python 2 on your computer and have them coexist in harmony.  Or rather, it had been possible to do that until recently.  Some newer operating systems like Ubuntu 24 not only don't install Python 2 in their default configuration, but don't allow you to install Python 2 at all, not even as an option.  Or at least not without circumventing the steps they've taken to stop you from doing it, and thus taking the chance of breaking your system in the process.  Apparently, that lack of Python 2 bothers nobody but oddballs like me.  The bottom line is that all Python 2 scripts in Virtual AGC have to be converted to Python 3.  I've done some of them so far.  Others will take longer.
  • And yet one more thing!  Eight or nine years ago, tired of supporting all of these various computer platforms (Windows, Mac OS, FreeBSD, Solaris, ...) which I never use personally if I can help it, I got the bright idea of dropping direct support for them, but instead providing Virtual AGC as a virtual machine (VM) that could be downloaded and run in hypervisors such as VirtualBox on any of these platforms.  And the VM worked great, I think.  Unfortunately, after some point I stupidly forgot to continue providing updated versions of Virtual AGC for that VM.  Yikes!  So the VM had become very out-of-date.  Not only that, but I've also found that since it was now based on such an old operating system (32-bit Ubuntu 14.04), I no longer could update Virtual AGC for the VM even if I got my motivational ducks in a row.  Virtual AGC simply requires a more-modern environment than 10-year-old 32-bit Ubuntu in the old VM to build and run.  Solution?  A new VM!  I've replaced that old VM with a completely new feature-packed VM that not only has more capabilities, but also by design can be very-easily updated without my having had to prepare such updates for them in advance!  In other words, users of the new VM will be protected from my future indolence after this burst of energy on my part has dissipated.  The key is that the new VM doubles as a very stable build machine for Virtual AGC, a capability which the old VM did not have, due to having been pared down to its bare essentials.  All of this stuff is thoroughly written up on a completely-revised and simplified download page, which has thrown out almost all of the old, useless stuff that's no longer supported, while hopefully better illustrating the use of the new. 
  • An added bonus is that the download page now includes something lacking up to now, namely build-instructions for Virtual AGC on Mac OS Sequoia that will (probably) work with any other recent versions of Mac OS too.

Another way of looking at most of the mumbo-jumbo above is that I want the new VM to be as perfect as humanly possible, and to provide as much of the Virtual AGC functionality that I enjoy on my own computer as it possibly can, without any of the hassle on users' parts that I have to endure for myself.  And to do that, I had to make sure that everything in Virtual AGC that was no longer up to my standards (as minimal as you may think them) was perfected at the same time.  The extent to which I've succeeded is always debatable, I suppose, but I'm very pleased with the result.

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