Hide 2018 change notes?
  • On the AGC assembly-language page of this site, my intention was always to create a comprehensive manual for AGC assembly language.  While this was somewhat successful for the AGC's so-called "basic" instructions, it turned out to be sadly completely inadequate for the AGC interpreter language, whose descriptive section was basically a promisory note for future content that I ended up never creating.  In other words, if you wanted to read anything about the interpreter instructions, you couldn't read my lovely verbiage about it, but would pretty much have to fall back on the original Instrumentation Lab documents.  Unthinkable!  But wait ... suddenly Mark Schulman (thanks, Mark!) has stepped in to fill the void I left.  He has written just such a guide for the interpreter language as I envisaged, and has gifted it to us.  I have basically inserted it verbatim into the assembly-language page of the website.  If the AGC interpreter is your thing, read and enjoy!
  • Steven Hauer has sent along a number of nice pictures of what's basically his implementation of Mike Stewart's Block II AGC emulator.  You can now read Steven's description and see his pictures on the physical-implementation page.
Changed the website's logo to read AGC McAGC Face.  Wait ... you can probably tell by looking in the upper right-hand corner of this page that that was a lame joke.    No, the truth is that Eugene Dorr has designed a number of alternatives to our old logo, which had simply been one of the NASA Apollo patches.  Several of Gene's designs stood out as clear favorites, but in the end there were 3 that I couldn't choose between.  So in an amazingly decisive fashion, I now have the website cycle through those 3 favorites on successive days of the month.  You can read all about this brave decision-making process on the FAQ page, if you're interested.
Volume 1 of the 1966 ND-1021042 has been added to the volume 2 provided a couple of days ago.  I think this addition is extremely important to anybody interested in simulating the AGC at the microcode ("control sequences") level, because our 1972 version of volume 1 was missing the roughly 175 pages that discuss the theory of operation of the "control sequences" but those pages are present in this 1966 version.  Naturally, the content might have changed a little from 1966 to 1972, but I don't think you're going to find a better discussion of the topic anywhere in our document library, or elsewhere, at the present time.  These documents came from the Mortimer family collection (thanks, Ken!) and the scanning at The Internet Archive was financed by Mike Stewart and me (thanks, us!).
Added the earliest (i.e., "no rev") version of the AC/Delco document ND-1021042, "Apollo Lunar Excursion Module Primary Guidance, Navigation, and Control System Manual", volume 2, to the document library.  (Volume 1 is currently being scanned, but won't be available for a while.)  We already had a much later (6 years later!) version of this document as well, and the differences between the versions are significant.  What's important is that these are basically "theory of electrical operation" documents for the Block II AGC, and so lots of evolution in the electrical design can be seen.  What's even more fun is that this version of the document may correspond to a specific AGC which physically still exists and could possibly be made to function; but that's just speculation at the moment, and so we may or may not have more to say about it at a later time.
Added a collection of papers on guidance, control, and flight dynamics from a 1967 AIAA conference.  At least some of them are directly related to Apollo guidance.
  • When I originally created the document library, it was an earlier, more-innocent time, when men were men, women were women, and what today seem like relatively small downloads then seemed like freakingly huge ones.  Ah, 2003, will you ever come again?  At any rate, so-called comedy aside, back then I tended to put a little note next to each of the hyperlinks to show how many megabytes were in each document file.  Well, times have changed, at least as far as download sizes are concerned, and those quaint, old notes warning you about 4MB or 5MB downloads now just seem silly now that many of our downloads are hundreds of megabytes.  Besides, 90% of the newer additions to the library no longer had notations like that anyway.  So I've just bit the bullet and removed all of the old notations about download sizes and/or document page counts.  It's just the right thing to do!
  • 4 new documents have wended their way to us from UHCL and have gone into the document library as well.  (I probably won't be able to actually upload them until later today or tomorrow, though, so don't be disappointed if their links don't work correctly just yet.)
Added Grumman's Level III PGNCS drawings for LTA-8 to the document library.  These are basically the detailed wiring diagrams for the lunar module, showing how all the bits and pieces of the guidance system (including the AGC) were interconnected.  LTA-8, according to online sources, was the first production, man-rated lunar module, and was used for testing purposes rather than flight.  The drawings still internally identify it as a "LEM" rather than a "LM".  A later drawing covering LM-4 through LM-15 was already in our library.
A somewhat later version of the Astrionics System Handbook, Saturn Launch Vehicles document has been added to supplement the earlier version already in our document library.  The newer version relates essentially to Apollo 12, while the earlier relates essentially to Apollo 11.  Of particular interest, the LVDC software was apparently significantly changed or even replaced between those two missions — a fact which I either didn't know or else had totally forgotten — and the associated Chapter 11 of the document seems to have been completely rewritten as a result..
Thymo van Beers has pointed out that the documentation for the CPU-Engine API and Backtrace API on the developer page have rotted a bit over the years, so that the descriptions no longer coincided exactly with the code.  So I've made several corrections to the text.  Thanks, Thymo!
The AC Electronics Block I study guide, "G&N System Familiarization" has been added to the document library.  Unlike the companion document added a couple of days ago, this one is much more obviously an actual study guide.  Both documents (and more Block I documents to follow) were contributed by the Mortimer family (thanks, Ken!); Mike Stewart and I (thanks, Mike and me!) are financing the scanning of these docs at The Internet Archive, where you can see the full-resolution scans if you're so inclined. 
Added a nifty AC Electronics study guide for Block I Guidance&Navigation Hardware Functions to the document library.  Like many other AC Electronics docs, it's so chock-full of detailed technical info that it might better be viewed as reference material rather than the "40 hour" training course it purports to be.  (I think the primary justification for labeling it as a training course is that every second page is left blank for the student to make hand-written notes. )  This is the first of several significant documents for the Block I AGC that we're having scanned by the Internet Archive right now, so stay tuned for the next few weeks if you're interested in Block I.
  • Added a workaround to the Raspberry Pi build instructions for a bug found in certain versions of the Raspbian software repository.  (Specifically, for the 2018-04-18 version of Raspbian, in which Virtual AGC builds but does not run under the previous instructions.)
  • In the document library, the icon now relates to documents added from May 2018 onward (rather than January 2018 onward).
  • Seven new documents added to the document library, of which the most significant are volumes 3 ("Control Data") and 4 ("Error Analysis") of the AS-278 GSOP, plus document E-1699.  The latter is a description (in the form of a proposal) for the physical construction of the AGC.  The remaining docs, which I won't list specifically here but which have arbitrarily been stuck with the electrical schematics, may or may not be useful in understanding discrepancies between the electrical schematics we have vs earlier physical AGC/DSKY units, but are not of general interest.
Apparently, on the COLOSSUS page, what I've been calling COLOSSUS 2B, 2C, and 2D (for Apollo 12, 13, and 14) for the last 15 years should really have been 2C, 2D, and 2E all along.  I've corrected that now.  Yikes!  What caused the error to be noticed today is the addition of two new documents in the document library:

These are, of course, the super-awesome Apollo 7 CM and Apollo 12 CM documents corresponding to the super-awesome Apollo 12 LM document added yesterday.  Not only is this super-awesome (had I mentioned that already?), but this is actually the first significant documentation we've ever gotten about the Apollo 7 software.  All three of these documents were written by AC Electronics residents at the Instrumentation Lab.

Four new documents were added to the document library, most of which are of lesser significance (from my limited perspective), so I won't bother itemizing them; just check out the icons in the library if you're interested. 

However, one document, titled "Guidance, Navigation, and Control Lunar Module Functional Description and Operation Using Flight Program LUMINARY (Rev. 116)" (600 pages), for the Apollo 12 LM, seems quite significant.  According to its preface, "The purpose of this document is twofold.  The first is to provide a functional description (operationally oriented) of the LM GNCS hardware and software and the interfaces with other spacecraft systems.  The level of detail is that required to identify and define telemetry outputs. Also included are function flow diagrams of the LUMINARY programs and routines together with lists of verbs, nouns, option codes, and checklist codes for this flow. The second purpose is to provide the operational procedures for this hardware and software including nominal airborne condensed checklists, malfunction procedures, and program notes."
I got a complaint that the VirtualAGC GUI program wouldn't fit on a 800×480 7" Raspberry Pi touchscreen.  No kidding!  Well, that's part of a larger problem with it, it appears, in that while the program was attempting to interrogate the screen size and to adjust it user-interface format appropriately, that feature doesn't seem to have been working.  So I've addressed both of those problems in the latest source-code updates in the GitHub repository.  Instead of trying to make adjustments according to the screen size, the VirtualAGC GUI program now depends on command-line options:
  • --radio-buttons — For the largest display screens (with, say, 1024 pixel rows).  Mission selection is the "traditional" way, via radio buttons in the user interface.
  • --dropdown — (The default.)  For smaller display screens (with, say, 720 pixel rows).  Mission selection is in the newer way, via a drop-down list.
  • --squish — For the smallest display screens (with, say, 480 pixel rows).

For use with --squish only, there's also a --maximize command-line option that maximizes the program at startup.

There are no installers for this new program version as of yet, but I'll get around to it sometime if I hear no complaints in the meantime.

Two significant documents were added to the document library:
  • Excerpts from "Apollo 11 LM Timeline Book" (1969), including handwritten notes made, I'm told, by Buzz Aldrin.  It is a notable addition to the collection, because we previously had no final version of the descent procedures specific to Apollo 11, and the procedures in this document differ from those cobbled together from the closest alternatives (Apollo 12 procedures or preliminary Apollo 11 procedures).  This information is necessary, for example, in making simulated Apollo 11 landings in NASSP that are faithful to the 1969 original landing.
  • Level III PGNCS drawings from Grumman.  These are basically souped-up versions for LM-4 through LM-15 of the LM ICD documents we already had, with more-detailed interconnection drawings and pinout information.  They're also significant in a different way, in that they are scans of "aperture cards" from the National Archives in Ft. Worth — a resource I had noted many years ago but had completely ignored, but which is now revealed as a potential treasure chest ... if only we could just figure out what that treasure chest contained so that we could ask for it! 
A new document was added to the document library, "Luminary 1B DAP Preflight Performance Evaluation" (thanks to Hartmuth Gutsche for spotting this doc for us).  It's an evaluation of the results of digital simulation of the digital autopilot of Luminary 116 (Apollo 12).  As it happens, we already had a digital simulation of Luminary 116 in our collection as well, but it was from a somewhat later time and isn't the simulation from which the report was written, presumably.
Two new LVDC-related documents were added to the document library, one sponsored and scanned by Mike Stewart (thanks Mike!), and one cleverly found in the NTRS stash by Nik Beug (thanks Nik!).  These are presently at the top of the LVDC section of the document-library page, and I invite you to read the descriptions there.  However, the more-significant of the two is a study (in 3 volumes), the "Flight Program Language Requirement" document, of the feasibility of replacing the LVDC assembly-language version of the LVDC software with versions in 4 different programming languages.  As a part of this effort, large chunks (but not 100%) of the pre-existing LVDC software were actually ported to those 4 alternate languages, as well as being flowcharted and described in detail.  Thus, though this document does not provide any LVDC code at all, it nevertheless provides much more internal detail about the LVDC software, in almost-usable form, than any other documentation presently available.  Unfortunately, it is not complete enough in itself to allow reconstructing the entire LVDC program.
There are a couple of new LVDC-related documents which Mike Stewart has managed to track down and have scanned on his own dime (thanks, Mike!):
  • "Interface Control Document: Definition of Saturn SA-513/SKYLAB 1 and SA-515/SKYLAB Backup Flight Sequence Program".  Notable for including a pinout of the LVDC and LVDA discrete inputs, discrete outputs, and interrupts, as well as a detailed mission-specific timeline of the theoretical behavior of those signals.
  • "Saturn V Flight Program Development".  Describes the development process for the LVDC software (in a software quality assurance sense), as well as giving a very high-level architectural overview of the software.  Needless to say, most of the specified documentation developed during this process is missing from our collection.  Among the more-interesting soundbytes:  The LVDC software-development process for each launch vehicle, took 61 weeks.
Replaced the photo of the Block I nav-bay DSKY on the Block I page with a much better one.
  • Added 13 COLOSSUS Memos to the document library.  We already had 12 such memos, but they were mixed in with the LUMINARY Memos, so to make them easier to find I created an entirely new section on the document library page exclusively for holding COLOSSUS memos.  Unfortunately, we know that the numbering for COLOSSUS memos goes up to at least 327, so fact that we now have 25 of them still leaves quite a few missing!  The new ones cover COLOSSUS revisions 197 through 221, with a few little gaps.
  • Similarly, I found a couple of SKYLARK Memos memos lurking amongst the LUMINARY Memos, and referenced them in the SKYLARK Memos section of the document-library page.
  • In dealing with the stuff above, I also happened to notice that various mission flight-plan documents which we'd previously been missing — Apollo 7, 10, 13, 14, Skylab, and ASTP —had become available on elsewhere on the web, so I've raided those documents from their original homes and added them to the document library as well.  In other words, nothing new in any larger sense, but now integrated into our document library.  A few other documents were mined and added in the same way ... just look for the icon within the document-library page.  One of the "new" documents, the Apollo Operations Handbook, Block II Spacecraft, isn't really new, but the copy we already had seems to have disappeared without a trace somehow.
  • Found a nice picture of the LVDC, which I've dutifully added to the LVDC page.

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