Hide 2019 change notes?
The electrical schematics for Block I AGC rope strand select module, namely drawing 1006099A, have been transcribed to CAD.  See also:  the renderings of the CAD as image files.  Like all of the analog modules transcribed so far that are based on reusable hierarchical circuit blocks, I haven't yet adjusted the reference designators in the child circuit blocks to correspond to those shown on the associated insulator drawings.  When I get around to that, there will be a script to do the job in an automated fashion.  For now, though, that means that those reference designators on the child sheets have been chosen arbitrarily by KiCad.  However, in the PNG renderings of the CAD files, they show up as identical to those shown on the original drawings, and you have to actually edit those components in KiCad to find out the actual reference designators used in the netlists.
CAD transcriptions of the electrical schematics of interface modules A20/A40 for the later-model Block I AGCs (1003700, 1003565) can be now be found in our CAD schematics repository.  There is also a folder of visual renderings of those CAD files as images.  Combined with the early-model transcriptions from the 6th, I think that all Block I AGC models now have transcriptions for modules A20/A40.
CAD transcriptions of the electrical schematics of interface modules A19/A39 for the later-model Block I AGCs (1003700, 1003565) can be now be found in our CAD schematics repository.  There is also a folder of visual renderings of those CAD files as images.  Combined with the early-model transcriptions from the 5th, I think that all Block I AGC models now have transcriptions for modules A19/A39.
CAD transcriptions of the electrical schematics of interface modules A20/A40 for the earliest-model Block I AGCs (1003186, 1003469) can be now be found in our CAD schematics repository.  There is also a folder of visual renderings of those CAD files as images.  Specifically, these are transcriptions of drawings 1006535B, 1006009G, and portions of 1006088A.  The circuitry for later Block I AGC models (1003700, 1003565) were from a different drawing which has not yet been transcribed.
CAD transcriptions of the electrical schematics of interface modules A19/A39 for the earliest-model Block I AGCs (1003186, 1003469) can be now be found in our CAD schematics repository.  There is also a folder of visual renderings of those CAD files as images.  Specifically, these are transcriptions of drawings 1006534C, 1006087B, and portions of 1006088A.  The circuitry for later Block I AGC models (1003700, 1003565) were from a different drawing which has not yet been transcribed.
The electrical schematics for Block I AGC module A38, namely drawing 1006551-, have been transcribed to CAD.  See also:  the renderings of the CAD as image files.  This happens to be the last of the Block I AGC logic modules (as opposed to analog and interface modules) — i.e., all of the logic modules have now been transcribed to CAD.  
  • In the very first Block I AGC schematic drawing I transcribed to CAD I had stupidly misread a connector-pin number, and since that very same block of circuitry appeared identically in the subsequent 17 Block I AGC schematics I've transcribed, I had ended up propagating the error into 18 CAD drawings.  Yay, me!  At any rate, that's now fixed, and shouldn't have had any effect on anybody anyway, since it was an "AGC 4" pin number rather than an "AGC 5" pin number.  Still ....
  • The electrical schematics for Block I AGC module A37, namely drawing 1006550F, have been transcribed to CAD.  See also:  the renderings of the CAD as image files. This was actually quite a monster of a task, because the "signal wiring diagram" associated with it (drawing 1006130-), which is needed for determining reference designators and input-pin assignments for the NOR gates, was essentially illegible regardless of how I attempted to post-process it.  Check it out if you think I'm exaggerating the horrific quality of this drawing!  Of course, I could have just ignored the wiring diagram completely and arbitrarily assigned these values without affecting the electrical functionality in any way, as I've already done for a couple of schematics in which the wiring diagrams were missing completely.  But for some reason I got the idea in my head that I could extract the NOR-gate reference designators and input-pin assignments from the wiring diagram in spite of the fact that the drawing itself was illegible.  And indeed, it turned to be almost possible to do that perfectly.  In the end, it turned out that only two gates which were wired in parallel couldn't be distinguished from each other, so that for them I had two reference designators and two gates and didn't know which went with which.  Hardly the worst problem one could have!  In other words, overall the reverse-engineering of the wiring diagram worked out quite well.  Pointless, I know, since it would seem so totally unnecessary to anyone not obsessed with authenticity, but weirdly satisfying in a digital-archaeology sense. 
The electrical schematics for Block I AGC modules A30-31, namely drawing 1006548-, have been transcribed to CAD.  See also:  the renderings of the CAD as image files.
The electrical schematics for Block I AGC module A29, namely drawing 1006559D, have been transcribed to CAD.  See also:  the renderings of the CAD as image files.
The electrical schematics for Block I AGC module A27, namely drawing 1006544B, have been transcribed to CAD.  See also:  the renderings of the CAD as image files.
The electrical schematics for Block I AGC module A25, namely drawing 1006554-, have been transcribed to CAD.  See also:  the renderings of the CAD as image files. Because no signal-wiring diagram was available for the transcription, the NOR-gate reference designators and input-pin assignments were unknown and had to be made arbitrarily.  But neither the electrical functionality nor the visual appearance of the schematic is affected by that problem, and it's only of interest to someone interested in duplicating the original physical layout of the electrical components of the module.
  • A couple of files whose names differed only in their case ("device.lib" and "Device.lib") had crept into the "schematics" branch of our git repository, where they would sabotage attempts to checkout the schematics in case-insensitive files-systems (like for Windows or Mac OS X); I never noticed it, since I use Linux, whose file-systems aren't crippled in that way.   But kidding (or is it?) aside, the reason I'm mentioning this relatively unimportant fix is that it involved elimination of a folder of KiCad symbol-library files, msSchematics/libs/, in which there's a remote chance someone could be interested in the future.  If so, just consult the original issue report to see how to find the folder in the repository history.
  • The electrical schematics for Block I AGC module A24, namely drawing 1006555A, have been transcribed to CAD.  See also:  the renderings of the CAD as image files.
The electrical schematics for Block I AGC module A23, namely drawing 1006545-, have been transcribed to CAD.  See also:  the renderings of the CAD as image files.  Because no signal-wiring diagram was available for the transcription, the NOR-gate reference designators and input-pin assignments were unknown and had to be made arbitrarily.  But neither the electrical functionality nor the visual appearance of the schematic is affected by that problem, and it's only of interest to someone interested in duplicating the original physical layout of the electrical components of the module.
The electrical schematics for Block I AGC module A22, namely drawing 1006553E, have been transcribed to CAD.  See also:  the renderings of the CAD as image files.
The electrical schematics for Block I AGC modules A1-A16, namely drawing 1006540A, have been transcribed to CAD, and cross-checked/corrected against the CAD schematics previously recovered from document ND-1021041 before the original drawing became available.  The usual PNG renderings of the CAD files for both versions are available.  The two implementations do differ slightly, with the difference being that one backplane signal in the ND-1021041 version has a higher drive capacity.  You can read the writeup about the discrepancies here, if you like.  This is actually a case where the availability of the official schematic doesn't necessarily obviate the need for the ND-1021041 schematic, because the latter contains a lot of information about backplane signals that the former does not.  In fact, between the two, it contains most of the information on that topic. 

Only the pages for AGC models 1003700-051 and 1003700-071 have been updated with this information, because we don't actually have the particular assembly drawings for the other Block I AGC models that would tell us that 1006540 is the proper schematic and 1006120 is the proper wiring diagram.

By the way, this is the last of the schematics that I "recovered" from ND-1021041 prior to the availability of the true original Block I drawings, so I am now officially caught up and can begin transcribing schematics for Block I AGC/DSKY modules that haven't been dealt with yet.  My final judgement on the schematics recovered from ND-1021041 is that ND-1021041 has a lot of errors in it, particularly in so far as connector pins are concerned, so it's good thing we now have the original drawings.  But in spite of that, ND-1021041 is almost always correct about everything else, and is a fantastic resource when working with this material.  Furthermore, most of the connector-pin errors seemed to have been the result of accidentally occasionally using pin numbers from an earlier version of the device, which is probably not a problem that would occur with the analogous Block II document ND-1021042.  Only a couple of things were uncovered that I interpreted as actual electrical errors in ND-1021041, though I had only recovered 7 modules, and 7 modules do not an AGC make.  So all in all, good job AC Electronics!
As foreshadowed in the last note, I have completed my automated comparison (using a newly-written Python script) between the CAD files for Block I AGC module A33-A34 that I transcribed from figures in AC Electronics document ND-1021041 (which I call 1006547r), vs the CAD files I transcribed from the official MIT/IL drawing 1006547G.  After fixing up errors in both CAD files that I found in this process, shockingly few discrepancies remained.  In point of fact, the only unresolvable discrepancy is that there is one NOR gate being used as an inverter between two pins on the backplane connector for which the backplane signal names for the input and output differ in the two different implementations of the CAD files ... so the process of recovering the schematic from ND-1021041 worked quite well for this module.  A full writeup about the discrepancy has been made.  I don't claim the automated comparison is perfect, of course, but I'm happy that it found stuff for me to fix.    At any rate, I'd now consider both these versions of the A33-A34 schematic to be checked and reasonably reliable, and will move on the next module rather than tarrying further with this module.
The schematic for the Block I AGC scalar module (namely drawing 1006547G) has been manually transcribed to KiCAD placed into our git schematics repository, along with the usual PNG rendering thereof.  This is the first actual Block I schematic drawing transcribed, since the previous Block I CAD files (including the scaler module) had instead been "recovered" from AC Electronics document ND-1021041.  Instead of proofing the CAD transcription, I think I'll do an automated comparison of its netlist vs the netlist of the "recovered" schematic (which I had called 1006547r).  That may take some doing, since the reference designators and pin numbers for the NOR gates won't match between the two, but I think it will be quite instructive since it will both be checking the transcription and the accuracy of ND-1021041 at the same time.
Completed writing the explanation about how Block I signal wiring diagrams work on the electro-mechanical page ... which I think finally brings the electro-mechanical page to completion, if not necessarily perfection.

Hide 2018 change notes?
Well, it took a while, but the electro-mechanical page has been basically restructured from the ground up and rewritten to both be a tad simpler and at the same time to provide far more actual electro-mechanical information than before.  Instead of providing the electrical drawings for a half-dozen Block II AGC/DSKY models as before, it provides electro-mechanical drawing trees (i.e., electrical and mechanical drawings) for 30 or so Block I and Block II AGC and DSKY models.  And could be made to provide quite a few more, if there turns out to be any reason to do so.  Admittedly, the drawing coverage is not perfect, since not only was NARA's coverage of the drawings a bit spotty, but also I had limited time to scan them ... and wasn't helped by the fact that the government (and consequently NARA) was shut down for the last week.  Okay, nothing's perfect! 

Incomplete or not, the restructuring provides a much more useful and interesting view of the AGC/DSKY electrical and mechanical design than we had before.  The electro-mechanical page is now a portal providing two main ways of browsing the set of available drawings:
  • A flat view of the drawing set, ordered by drawing number and revision.
  • A hierarchical view of the drawing set, ordered by G&N (Guidance & Navigation) system type ... or if you prefer to think of it that way, by Apollo mission number, or by AGC or DSKY part number.  In this hierarchical view, you navigate through the drawings on an assembly-by-assembly basis for whatever G&N system, mission number, or AGC/DSKY part number you feel like.

All other supplemental information provided by the electro-mechanical page is now subordinated to this basic drawing-browsing activity.

Some information that I deemed uninteresting and distracting was (gasp!) even removed from the page entirely, and not provided separately.  I don't know that I've ever done anything like that before.  It was only the table of serial numbers for AGCs and DSKYs that was removed, though, and I felt the information was buggy and too difficult to correct, so I don't actually think losing it is much of a loss at all.  If anyone disagrees and thinks it was valuable in some way, drop me a line.

Now that the drawings are arranged in this fashion, I'll have to somewhat modify my prior claims that we now have all of the DSKY and AGC schematics.  There are so many engineering drawings needed for any given model of AGC or DSKY that there's no single AGC or DSKY model for which we have anything like a full set of drawings.  Naturally, I'd like to have a complete set, not just for some AGC/DSKY model, but for all of them.

On the other hand, all of the models are generally so similar — after all, all of the AGCs in either of the two "blocks" can run the same software as any of the others, mostly, so how different could they really be? — that there's a lot of mixing and matching among different unit types that you can do.  In that sense, we have most of the drawings in so many different versions, you can almost always find something that will work for you if you don't have the specific drawing you want, either electrically or mechanically.  In that sense, you could say we not only have have all of the drawings, but have them many times over.

What?  You think that sounds specious?  It's a glass-half-full glass-half-empty thing here, people, work with me to overlook the problems! 

At any rate, over the course of 2019 I'll be working to fill in the gaps in the AGC/DSKY drawing-set as much as possible.  There's also the possibility of extending it to other G&N components such as the CDU, since NARA has drawings for basically all of the G&N components.  And I'll also return to transcribing the Block I schematics into CAD, which is what I was doing before I started spending every day over at NARA.  It will be a lot easier now that I actually have real Block I drawings instead of having to "recover" schematics from the bits and pieces in AC Electronics document ND-1021041.  It will be interesting to compare the real schematics (once they're in CAD) to the "recovered" ones I made before we discovered that the real drawings still exist.

Finally, as usual, I'll note that since the changes to the electro-mechanical page are so sweeping, it's unavoidable that there are bugs in it, particularly in the new drawing trees.  Hopefully we'll be able to clean those up in a timely fashion.

As mentioned on the note for the 15th, there's now a section on the document-library page for documents (as opposed to engineering drawings) that I scanned from the microform "aperture cards" at NARA Southwest.  This section is now completely up-to-date with respect to all such scans.  (In fact, this entire website is now up-to-date with respect to all the scanning done at NARA.)  These documents are distinguished by the fact that time and money pressure caused me to scan them in a really sleazy fashion, using a portable flatbed scanner, rather than the fancy NARA equipment, so the document scans are incredibly poor quality.  The results are very uneven, with many pages having been digitized quite well, but with the majority having some blurry parts, and a few pages even being illegible.  My excuse is that the scans are better than nothing, and you wouldn't have them at all if I hadn't done it that way.  So there!  Even so, I think I'll try to improve on my method the next time I go out for a round of scanning at NARA ... which may be a very long time, since the government is now in a shutdown mode that will likely keep NARA closed until 2019, when my vacation time will be back at zero.
  • The MIT/IL engineering-drawing index page has been updated to include all of the engineering drawings I scanned this week at NARA.  There are over 4400 scans in all now.
  • Various documents related to midcourse-correction processor for NASA's RTCC (Real Time Computer Complex) have been added to the Apollo 11, 13, 14, 15, and 16 items in the document library's "miscellaneous mission documents" section.  The full-quality scans are over at our Internet Archive site as well, though I'm going to stop providing explicit double-links (local low-quality plus Internet Archive high-quality).  If you wonder whether a higher-quality version is available for some document or the other, just head over there and look.  But as far as these particular documents are concerned, I'm told they're particularly valuable (for something relating to the RTCC rather than the AGC ) because they organize together in one place information that previously difficult to access because it was spread out over a number of hard-to-get memos.  Check them out.  From my perspective, the document on abort-plans for Apollo 11 seems particularly interesting.
The MIT/IL engineering-drawing index page has been completely replaced by a single unified index, arranged by drawing number.  (Previously, it was a set of "batches", each one of which was by drawing number.)  It doesn't really affect how you use it too much, but it just seems less amateurish.
I've not really been updating the website lately, even with the huge number of drawings I've been scanning at NARA SW every day, because I've simply been too busy and tired out by the process. Nevertheless, I did take the time today to update the page about NARA (or as it's charmingly titled, "Documentation Quest! Stalking the Wild AGC"):
  • The section about my previous finding aids for NARA has been updated with the possibly-important info that in 2010, NARA put all the documents I carefully indexed in 2004 into new boxes, with different numbers written on them.  Yay!
  • In 2004, I had scanned all of the title pages of documents in boxes I thought might be of future interest, but that there was no time back then to deal with.  For some insane reason I left these scans as TIFFs which, at least in my browser, you can't directly view.  Similarly, a finding aid from NARA itself was left in a Microsoft Word format that's not useful in a web browser.  At any rate, I've now converted these to PNGs and PDF, respectively, making them far more convenient for web purposes.
  • I've added a new section with finding aids and hopefully-helpful info about my present efforts at NARA to extract drawings from "aperture cards".

I've also updated our document library page with a couple of document I scanned from NARA's aperture cards.  There's actually an entirely new section on our document library page with just these two document, also I expect it to grow somewhat over the remainder of the year.

Finally, the indices for all drawings scanned this week (batches 3 through 7) have been added to our MIT/IL Engineering Drawing Index page.

The vast number of MIT/IL AGC/DSKY engineering drawings received over the past weeks — not just those drawings I've been scanning at NARA SW, but various others that associates have handed me — has both overwhelmed the main content on the electro-mechanical page (namely, drawing trees for the electrical design of specific AGC/DSKY models) and swamped my ability to deal with the new drawings in any timely fashion.  One thing I've done to deal with that is to split out all of the drawing-index Appendices formerly on the electro-mechanical page, onto a new MIT/IL AGC/DSKY engineering-drawing page, whose sole purpose is to index those drawings.  I've also pepped up my ability automate the indexing process somewhat, so hopefully in the coming week(s) I'll be able to stay abreast of the new incoming drawings on a day-to-day basis.  We'll see.  At least for now, I think I'm caught up, and the index page is complete with respect to all available drawings in our collection.
  • The revision code for the Block I AGC program Corona, flown on AS-202, previously unknown, is now known.  It was rev 261.  The Corona entry on the Colossus page has been updated accordingly.
  • We now have the AC Electronics manual for Apollo 11.  (Thanks, James Berry!)  Previously, we had only the Apollo 15 and 16 versions, so it's great to add Apollo 11 into that mix with its 50th anniversary looming.  The archival-quality page scans are on our Internet Archive site, while the lower-quality PDF with searchable text is here locally in our document library.  The book — which, never having seen one in person I was surprised to find really is a "book" rather than a jumble of papers loosely bound together, printed specifically as what's typically called a "trade paper edition" book — was purchased in a used-book store many years ago for $5, after apparently having been sold by the MSC employee who originally owned it.  Which just goes to show that used-book stores are great places.  But I already knew that.
I've been increasingly concerned for a number of reasons about the way the electro-mechanical page has been handling links into document ND-1021042, as well as links to CAD files and the PNG renderings thereof.  Consequently, I've completely restructured that portion of it.  It should now be easier to maintain in the future and (marginally) less confusing and easier to use right now.  On the bad side, all of the old hyperlinks on this change-log page to the PNG files rendered from CAD will no longer work, and I see no particular reason to fix them.  Seems like a small price to pay on a go-forward basis.  Still ... there may be some broken links to PNGs floating around elsewhere that I'll have to find and fix at some point.
Apparently I managed to treat the Universe right in my last post ... took me long enough to figure out how to do that!  I wish I had known the trick decades ago.

Kidding aside, though, the Instrumentation Lab Block I electrical drawings I alluded to yesterday have magically appeared overnight, and I've incorporated them into our electro-mechanical page.  I'm missing a couple of DSKY drawings, so perhaps I messed up when I made my shopping list and will have to try again.  At any rate, what has been added is a complete set of the official electrical schematics for the Block I AGC p/n 1003700, and mostly-complete sets (missing the keyboard module) for Block I nav & main DSKYs 1003706 & 1003707.  You have to take that with a slight grain of salt, since most of the drawings are actually 1 or 2 revisions off from what we were looking for; but I'm not sure how much confidence we can have that the revisions we were looking for were necessarily the right ones anyway, so that doesn't sound like a great problem.  Particularly not when the alternative situation (yesterday!) was that we had none of the Block I official drawings at all.  In fact, whether or not we have the precise revisions we were targeting, we have lots and lots of revisions we weren't targeting.  A typical example might be that we were targeting rev G of a drawing but only got revs -, A, ..., F.  Lest you doubt my word, there are over 200 such drawing scans.

At any rate, significant changes have been made to the electro-mechanical page to accommodate all of this new material:
Added the recovered CAD drawing for 1006556 (Block I AGC module A21, "logic flow S").  Contrary to my usual habit, I've only made the CAD files and haven't bothered with the PNG files, for a reason which will become apparent in a moment.  By the way, this particular drawing turned out to be a monstrous effort.  It was split out into 23 separate figures in ND-1021041, but lots and lots of that was little duplicated blocks of circuitry (presumably for clarity), replete with errors in terms of connector pin numbering ... all of which had to be resolved.  What fun!

Besides not making the PNG files for this drawing, I'm also going to pause most of the effort of recovering the rest of the Block I schematics from AC Electronics document ND-1021041 for the moment.  Why?  Well, because of some crazy news I got today.  As you know, we don't have the official drawings for the Block I schematics, and that's why I've been resorting to "recovering" them from the blocks of circuitry in ND-1021041's figures.  That's obviously not 100% satisfactory (though it's infinitely better than having no schematics at all ), because of the errors and omissions inherent in AC Electronics's redrafting of the drawings, the lack of versioning of the drawings obtained in this way, and the fact that the "recovered" drawings simply look nothing like the originals.  But in theory, the recovery process should still produce a very close approximation of the original design, if AC Electronics didn't screw up too badly.

Whatever.  The crazy news from today is that it looks like there's a high probability of getting the official drawings themselves in the near future, for both the AGC and the main/nav DSKYs ... all except drawing 1006545 (AGC module A23).  So I'll still recover that one from ND-1021041.

Anyway, I don't want to say much more than that right now, since the Universe doesn't like that kind of thing and would probably try to queer the deal if I did.   The transcriptions done so far won't be a total waste, of course, since if we do manage to get and transcribe the official drawings, when we can use the recovered drawings to do automated cross-checks of the netlists and what-not.  Even so, the time spent on it is time I'm not going to be getting back, unless karma is a real thing.
  • Steven Hauer was kind enough to send in updated descriptions and additional photos of his project to implement a physical AGC and DSKY using Mike Stewart's groundwork in capturing Block II schematics from the drawings Eldon Hall contributed plus document ND-1021042.  Naturally, I've updated our physical-implementations page accordingly.  Looks as though it's running pretty well now, though it's still a work in progress!
  • All of the Block I schematics transcribed from ND-1021041 so far have been tweaked, particularly insofar as their power-supply filtering circuits were concerned.  (Somehow I had failed to put in the values of the filtering capacitors.  Yikes!)
  • Drawing 1006543 has been recovered from ND-1021041.  It is the Block I "logic flow C" module A17, and is a pot pourri of various stuff, with the largest contribution being parity logic.  Links for the various CAD and PNG files are here.  There were lots of pin-numbering errors in ND-1021041, so I had to arbitrarily reassign various signals to otherwise-unused pins.  That's a normal experience with these drawings, but there were quite a few more errors than usual, given the relative simplicity of this module's schematics.  I hope the number of wiring errors doesn't turn out to be comparable!
  • Drawing 1006542 has been recovered as well.  It is the Block I "logic flow B" module, A18.  Here are the CAD and PNG links.  Frankly, in spite of having spent the day with it, I'm not entirely clear exactly what the stuff in it is for yet, so I can't give you a concise buzzword for the module's functionality.
Added the recovered Block I CAD drawing from ND-1021041 for 1006540 (AGC modules A1-A16, "logic flow bit").  There's one module for each of the 16 bits (including parity) in the memory/register words, each using the same physical module, but different signals are input and output to each of them from the backplane.  Plus, a number of internal signals are presented to the backplane and can be wired up differently there, creating circuits that are superficially somewhat different from what you'd naively expect from the drawing.  So while the drawing itself is deceptively simple, it's actually quite a mess of different types of signals and a not-necessarily-obvious circuit topology.  Plus, ND-1021041 had a number of inconsistencies in it.  In other words, the usual warnings about how it's likely there are a lot of errors that will have to be worked out of the drawing later, yada, yada, yada.  And the usual statement that so far I'm pleased with it.  I don't know why I even bother with these disclaimers any more, since they're always the same!  (KiCad schematics, and PNG renderings of the main sheet and a sheet with tables of backplane signal names.)
There had been 3 Block I AGC circuits in ND-1021041's Figures for which, at first, I hadn't been able to determine the modules to which they belonged.  I think I've now moved them into the proper modules in the AGC 1003700 section of the electro-mechanical page.
On the electro-mechanical page, rearranged the Block I AGC hyperlinks into document ND-1021041 so that they're a bit more useful.
I've had second thoughts about the scheme I mentioned yesterday of simply using KiCad default page templates for the Block I drawings' title blocks.  I've modified the default somewhat by including a Virtual AGC logo and project name in the title block, along with some other changes to slightly reduce the ugliness of the things.  Consequently, the yesterday's transcription of Block I drawing 1006547 has been tweaked a tad.

Mainly, though , I recovered CAD drawings from document ND-1021041 for Block I AGC schematic drawing 1006552, "Logic Flow N", module A28, which corresponds roughly to a portion of Block II timer module A2.  (KiCad schematics and PNG renderings of top-level sheet plus sheets corresponding to ND-1021041 Figures 4-53, 4-57, 4-59, 4-62, 4-143, and 4-181.)  It went much better than yesterday's drawing, with no obvious errors in document ND-1021041. 

There is a problem with the Block I transcriptions that I forgot to mention yesterday, though, in that ND-1021041 doesn't always list backplane signal names in its schematics when the connectivity is obvious from the drawing, so if you have just the transcribed schematics, you can't deduce all of the backplane connections from it.  I'm currently assigning those otherwise-unnamed connector pins with names like PM_N, where M is the module number and N is the pin number.  I supplement that scheme by maintaining a connectivity database as I go along that tells which of the PM_N pins are connected to which other PM_N pins.    For example, pins P33_65 and P33_77 in module A33 are connected to pin P34_53 via the backplane.

Eventually I'll eliminate the PM_N names entirely, by assigning unique but logically-reasonable or arbitrary names to those as-yet-unnamed backplane nets.  That's simply not too convenient at this stage.  For now, for drawings I've already transcribed, the files pinsBlockI.txt and connectionsBlockI.txt in our github repository can be used to get lists of block I backplane connector pin names and of backplane nets that aren't yet obvious from the pin names.  Fortunately, there aren't too many of them, percentage-wise.

Finally, as an afterthought , I've added the CAD transcription for Block I AGC drawing 1006549, "Logic Flow J", module A26.  (KiCad schematics and PNG renderings for the top-level sheet and for sheets corresponding to ND-1021041 Figures 4-61 and 4-181.)
I've "recovered" or "regenerated" my first first draft of a Block I AGC schematic drawing, namely drawing 1006547, "Logic Flow G", modules A33 and A34, which corresponds roughly to the Block II scaler module A1.  By "recovery", I'm referring to the fact that we don't have a copy of any of the revisions of the official drawing 1006547, but we do have AC Electronics document ND-1021041.  ND-1021041 seemingly contains the entire Block I AGC schematics, but redrawn and grouped logically across a large set of Figures.  For example, all of the schematics for drawing 1006747 seem to be in Figures 4-59, 4-153, 4-165, and 4-181.

There are pluses and minuses to this recovery process.  For one thing, ND-1021041 is far more legible than any of our scans of the official AGC schematic drawings.  On the other hand, though these schematics are functionally identical (hopefully!) they are by no means visually identical to the originals, so it still leaves us without a clue as to how the originals actually looked.  Nor does ND-1021041 have any of the original notes from the drawings, nor the parts lists that usually appeared as tables in the originals.  So I've eliminated certain visual conceits in my transcription, such as no longer adding Instrumentation Labs borders or title blocks to them.

And frankly, if my experience so far is in any way representative, ND-1021041 introduced a lot of drafting errors that were not present in the original drawings.  Consequently, these "first drafts" are more "drafty" than we're used to , and it will take longer to wring out the errors from them.  Though once I've recovered enough of the logic modules to perform Verilog simulations of the logic — i.e., to run Block I software on the simulated electronics — we can obviously start to feel good about the process; but that's somewhere in the distant future right now.  Fortunately, a lot of drawing 1006547 should be simulable in a stand-alone fashion, though I haven't done it just yet.

With that said, I'm pretty pleased with this very first drawing.  As usual, we have the KiCad schematics, along with PNG renderings of them: top-level sheet, and sheets roughly corresponding to ND-1021041 Figures 4-59, 4-153, 4-165, and 4-181.
Added transcription of drawing 2005012B (fixed memory module B1-6 for all AGC models).  The KiCad schematics are here, and we also have PNG renderings from the CAD for the drawing (sheet 1 and sheet 2).  I don't mind telling you that transcription of this one was a real pain.  On the other hand, it's nice to have a drawing that's actually legible, so that you can get a sense of what the module is actually doing, rather than just wondering if you're going blind.    This is a significant milestone, though, because

We now have complete transcriptions to CAD of all of the original Apollo Program electrical schematics for AGC p/n 2003200, as well as renderings of them in PNG form.  The digital portions of the circuitry have been converted to Verilog for simulation purposes, and the simulated electronics can run the AGC suite of validation software without error.

Sweet!  Admittedly, this CAD transcription might benefit from a good proof-reading of the PNG renderings vs the original scans.  (Volunteers?)  And simulation of some of the the analog circuitry (such as the power supply and oscillators) with some variant of Spice might be nice.  In fact, there's no end of extra work that could be done on it.  The complete story, as usual, is on our electro-mechanical page.  But I think it's pretty swell anyway.

That's not the end of the CAD-transcription story, of course, in that there are two other versions of the Block II AGC with schematic drawings remaining to be transcribed or regenerated, plus the Block I AGC, plus intermediate revisions of the schematic drawings, plus mechanical drawings.  May take a while.

In an unrelated development, the comments about the AGC's integrated-circuit usage on the electro-mechanical page have been tweaked to account for the Block I AGC's NOR-gates, as well as sense-amplifier integrated circuits.
Added transcription of drawing 2005106- (erasable memory module B12 for AGC 2003200).  The KiCad schematics are here, and the PNG rendering is here.
Added transcription of drawing 2005100D (rope driver modules B16-B17 for AGC 2003200).  The KiCad schematics are here; as is usual for these last few modules, there are separate PNG renderings for visual correspondence to the original (sheets 1 and 2) and for electrical correspondence (top-level sheet and circuit blocks A, B, C).  This is kind of a milestone, in that all of the AGC (2003200) modules have been transcribed to CAD other than B1-B6 and B12, which are the modules that really consist only of ferrite cores.  I'm not sure it makes much sense to transcribe those anyway, though in a slavish, compulsive fashion I'll undoubtedly do so, so I'll just hold off for a while on declaring a true milestone. 
Added transcription of drawing 2005924- (strand select module B15, for AGC 2003200).  The KiCad schematics are here; there are separate PNG renderings for visual fidelity (single sheet) vs electrical properties (top-level sheet and circuit blocks A, B, C).
  • Added transcriptions of drawing 2005919A (sense amplifier module B14, for AGC 2003200).  This module seems to be structurally identical to yesterday's drawing 2005920B (module B13), but with the backplane connector pins carrying different signals, so I'm not sure why it's a separate drawing.  For AGC 2003100, it was actually one single drawing (and module p/n).  Possibly there's some difference I've overlooked.  Moreover, this called my attention to several errors I had made in the transcription of 2005920B, so I'm a bit uneasy that a few more bugs are lurking in both ....  At any rate, the KiCad schematics are here.  Likewise, there are separate PNG renderings for visual fidelity (sheets 1 and 2) vs electrical properties (top-level sheet and its sub-circuit).
  • Hoping to combat the complexity of this website (at least a little!) added a brief cheat-sheet of hyperlinks to the top of the main page. I know, I know!  I invariably combat complexity by adding more complexity.
  • Added some fun anecdotal info to the description of the TRIVIUM program now residing on our Colossus page.
  • Fixed a wiring bug reported by a correspondent, in the CAD transcription and PNGs of drawing 2005916A.
  • Added transcription of drawing 2005005D (current switch module B11, for AGC p/n 2003100 and 2003200) into CAD.  The KiCad schematics are here, and PNG renderings (sheets 1 & 2) are also available.
  • Added transcription(s) of drawing 2005920B (sense amplifier module B13, for AGC 2003200).  The KiCad schematics are here.  Like yesterday's drawing 2005104B, it's not possible to make a CAD transcription of 2005920B that's both electrically correct and visually accurate with respect to the original.  Therefore, separate transcriptions have been made for visual fidelity (PNGs for sheets 1 and 2) vs electrical properties (PNGs for top-level sheet and its sub-circuit).
Added the transcription of drawing 2005104B (erasable driver module B9&B10, for AGC p/n 2003200) into CAD.  The KiCad schematic files are here.  It proved impossible to make a single transcription that was simultaneously a good visual representation and an electrically valid representation of the original drawing.  Therefore, two separate transcriptions were made, one intended to be visually accurate, and the other intended to be electrically valid and accurate.  The KiCad projects for both (original.pro and module.pro, respectively) are at the link just given.  PNG files for both the original visual (sheet 1 and 2) and the electrical (top level, circuit blocks A and B) are also available.
Drawing 2005922- (alarm module B8, for AGC p/n 2003200 — or at least, a very close revision to the desired 2005922A) added.  KiCad schematic files and PNGs (sheets 1, 2, and 3) all available.
Drawing 2005003E (oscillator module B7, for AGC p/n 2003200) has been transcribed to CAD.  The KiCad drawings are available, as well as PNG printouts of its sheets 1, 2, and 3.
Drawing 2005916A (power-supply modules A30-A31, for AGC p/n 2003200) has been transcribed to CAD.  The KiCad drawings are available, as well as PNG printouts of its sheet 1 and sheet 2.  With this drawing now available, all of the A-modules for AGC 2003200 have now been transcribed to CAD. Next, the B-module drawings!
Similarly to yesterday's update, I added links into document ND-1021041 for the module electrical schematics for the Block I main-panel DSKY and navigation-panel DSKY.  All of these lists of link are only positioned temporarily, until I can move them into the document-index Appendix of the electro-mechanical page.  Luckily, this gave me the opportunity to fix a problem with the descriptions of the Block I DSKYs on the electro-mechanical page, in that the drawing lists for each of them indicated that there were 18 circuit modules (D1-D18), whereas the photographs only showed about half that many modules, with no obvious spaces where many more of them could be hidden from view.  Well, it's now clear that 9 of the modules listed were only for the main DSKY (D4-6, 11-14, 16, 17), and other 9 were only for the NAV DSKY (D1-3, 7-10, 15, 17).  I've fixed my drawing lists accordingly.  Problem solved!
In the Block I AGC (model #1003700) section of the electro-mechanical page, I've added links into document ND-1021041 for each of the module electrical schematics.  There are probably errors to fix, and the info will probably be reorganized later on, but for right now at least, it's a big help in trying to understand any given Block I AGC module is for.  It will certainly be a big help later on when trying to create CAD schematics for the various drawings comprising AGC 1003700.  I've not yet done the corresponding indexing of the Block I DSKY schematics.
  • I've put in a considerable effort creating a software tool that can statically compare Mike Stewart's preexisting KiCad/Verilog implementation of the AGC electronics with the identical-in-spirit but very-different-in-detail KiCad/Verilog implementation I've been creating.  The two implementations were effectively identical in behavior in terms of running the AGC validation-suite software before I started statically comparing the models, and I'm pleased to say that even though the static comparison found a half-dozen or so wiring errors in each of the two implementations, their behavior is still effectively identical now that those errors are fixed.  Admittedly, not all of the fixes to Mike's simulation have been pushed upstream yet, but hopefully we'll be able to manage that at some point.   I'm not pretending that either implementation is perfect yet, and I haven't completed my checkout of them, but I think this is a significant milestone in the journey towards that goal.
  • Due to the schematic wiring-error fixes just mentioned, as well as to recent improvements in KiCad's ability to render our schematics, all of the PNG images for the schematics I've been creating have now been re-rendered on the website (though they're uploading as I write this, and it may be a while before they manage to finish doing so).  They look a lot prettier, particularly when viewed on smaller screens or printed on smaller paper.  Even the E-sized drawings are legible when printed on U.S. letter-sized paper, assuming you're wearing powerful enough reading glasses, though for my old eyes, tabloid-sized paper (11"×17") is considerably more comfortable to read. 
  • Some descriptive material on the electro-mechanical page and hardware-simulation page has been updated.  They're both very much still works-in-progress, particularly the latter page.
  • One of the documents from Russ Larson's papers, namely the YUL documentation mentioned last time, actually has a very short Block I AGC sample program called TRIVIUM (by "IMA NIT-PICKER") attached to the end of it.  Considering that this is only the 2nd Block I AGC program we've ever seen, after Solarium, that's reasonably exciting.  At any rate, TRIVIUM has therefore been transcribed to source code, and added to our repertoire of AGC programs.  Because its purpose was to demonstrate the usage of YUL, TRIVIUM contained some deliberate errors that actually made its assembly by YUL (or yaYUL) fail, so I've also created a version called "TRIVIUM-repaired" that has those errors fixed, and added that program on github as well.
  • We've gotten in a heap of SCDs, or "specification control drawings", for the various electronic and mechanical components used in the AGC and DSKY designs.  For our purpose, these basically serve the purpose of manufacturers' datasheets for the components, and we have them for all but a handful of the parts used in the electrical/mechanical design.
  • The Verilog-based simulation of the AGC electrical design that I've been mentioning in the last few updates has reached the point of being able to run (and pass) the AGC's suite of Validation software that we use to help insure the accuracy of yaAGC.  That's not to say that it's perfect, since there are still known discrepancies between the simulation's behavior at a very-detailed level and Mike Stewart's earlier, independently-created simulation.  I'm tracking down those errors and fixing them over time.  Also, the even fancier Borealis software test suite hasn't yet been tried, since there are various technical problems with doing so that will need to be overcome first.
  • Another AGC schematic has been transcribed, this time for AGC module A52, drawing 2003305B, the "restart monitor", and thus added to the Electro-Mechanical page.
  • Pepped up the acknowledgements section quite a bit, on the basis of new documents I've gotten, to show more AGC developers and better-defined responsibilities with respect to the sections of the code they were responsible for.  It still very incomplete and unsatisfactory in spite of that.
  • I'm pleased to note that in the software repository we now have at least a primitive version of a KiCad-to-Verilog translator script (in Python) that works for several of our transcriptions of AGC modules. Indeed, hardware simulation of AGC module A1 (drawing 2005259A) actually works and behaves identically with what ND-1021042 says it should.  So as far as I can tell right now, that means that the CAD for module A1 is 100% correct.  But I want to write that up in detail at some point, with pictures, and haven't done so yet.  Plus, it still leaves us a pretty long way from running a full simulation of the complete AGC logic.  You can't sneeze at progress, though!
  • Added a heap of documents Don Eyles sent in, mostly memos.  I believe there were 89 in all, so on the document-library page I got rid of all the pre-existing icons to help them stand out.  The vast bulk of them are in the LUMINARY Memos section, with the remainder, I believe, being in the SCB Meeting Notes section and the Miscellaneous Mission Documents section.  There's some pretty interesting stuff in there.
  • The scans of volume 2 of document ND-1021041 (AC Electronics Block I manual) have undergone the cleanups mentioned a few days back, so that document is in its final form now.
  • The CAD transcriptions for AGC modules A19-A24 are now available on the electro-mechanical page (meaning that A1-A29 are now all available), for AGC p/n 2003200.  They've also undergone cross-checking and comparison against Mike Stewart's pin database for the AGC backplane (into which the modules plug), which is in turn based partially on Mike's earlier, independent transcription into CAD and subsequent hardware simulation, so I think we can start to have a little confidence in these new CAD transcriptions.  (The reason for these new transcriptions is that Mike's earlier ones weren't intended to duplicate the visual appearance of the original schematics, nor to reflect versioning differences, but merely to relect the final version of the hardware as accurately as possible.)  Roadmap-wise, this should be the minimal set of drawings needed for hardware simulation of the AGC logic (as opposed to its analog characteristics), so that is something I'm going to start thinking about seriously now, as well as transcription of all of the drawing versions that haven't been transcribed yet, extending to the later model 2003993, and the earlier model 2003100.
  • The electro-mechanical page has been very slightly reworked, reorganized, and cut down, so as to make it friendlier to newcomers.  Not much, I admit, but every bit helps.  A little.  Maybe.
Added CAD transcription for drawing 2005268A (electrical schematics for AGC module A18) to the electro-mechanical page: CAD files, PNGs generated from CAD (sheets 1 and 2), vs the original scans (sheets 1 and 2).
Added CAD transcription for drawing 2005267A (electrical schematics of AGC module A17) to the electro-mechanical page: CAD files, PNGs generated from CAD (sheets 1 and 2), vs the original scans (sheets 1 and 2).
  • Added a handful of new docs to the document library, mostly for the Apollo-Soyuz Test Project (ASTP), of which the gems seem to be the SKYLARK 48 erasable loads and the users' guide.  Now if only we had a copy of the SKYLARK program listing, then we'd really have something!
  • Both volumes of AC Electronics manual ND-1021041 for Block I are now available, including essentially-complete Block I AGC/DSKY electrical schematics.  Reduced-size scans (vol 1 and vol 2) are available, as well as the full-resolution scans (vol 1 and vol 2).  I am told, though, that additional work is may be done on both volumes at archive.org, so this document may change somewhat over the course of the next week or two.  At any rate, thanks, Ken Mortimer!
  • Cleaned up the master list of links to AGC/DSKY electro-mechanical drawings.  Specifically, I simplified how the links to figures in ND-1021042 are presented, and completed adding all of the links into ND-1021042 (in both versions of the document that we have).  I've not yet started adding Block I links from figures in ND-1021041 into the table.
  • And here's a cool article about the AGC and people working on preservation of them.  Quite a fun read, not just with AGCs, but with references to people (and sometimes pictures of them) familiar to people who frequent this website.  Assuming there are any, of course.
Added CAD transcription of the electrical schematics for the AGC interface modules A27/A38/A29, namely drawing 2005912B.  This is for AGC p/n 2003200, but is likely essentially the same as for the flight AGC 2003993.  CAD files here, plus PNGs (main page, circuits A, D, P, R, XT, Y), vs the original scans (sheets 1 and 2).  Note that what I call the "main page" of the CAD corresponds to sheet 2 of the original drawing, while sheet 1 original drawing is split into 6 separate CAD drawings of sub-circuits.
Added CAD transcription of the electrical schematics for the AGC interface modules A25 & A26, namely drawing 2005021C (but for AGC p/n 2003100 and 2003200, rather than the flight AGC 2003993): CAD files here, plus PNGs (main page, circuits XT, P, D, C, R), vs the original scan.  This is an interesting design relative to the drawings I've been adding so far, in the sense that those prior drawings all provided a "flat" design, whereas today's is purely hierarchical.  In other words, even though the prior drawings may have consisted of two or three sheets sometimes, that was really only due to the fact that the design was simply too big to fit on a single page, so the designers split it up into more.  If you had a big enough piece of paper, you could have stuck the stuff on all those sheets onto the one large page with no other change.  With the interface module, however, the design uses 5 smaller subcircuits, represented by separate CAD files that appear over and over again in the main circuit.  For example, the "P" subcircuit appears more than 10 times, while the "C" subcircuit is used over 30 times.  Unfortunately, that added complexity causes the CAD design to look not quite as similar to the original drawing, but it still is a pretty fair visual approximation. Fun stuff.
Added a CAD transcription of the electrical schematics for AGC module A16, namely drawing 2005266-:  CAD files here plus PNGs of sheets 1 and 2, vs the original scans of 1 and 2.  (I suppose I should have been providing similar links to these notes for all of the CAD drawings I've been adding over the last few weeks, but it didn't occur to me.  I'll try to remember to add them for future drawings, but for those already added to the electro-mechanical page, I'm afraid you'll just have to rummage around to find them if you're interested.)
  • Added an electrical CAD transcription for yet another revision of AGC module A14, this time for drawing 2005264- (to complete the set started with drawings 2005264A and 2005264B yesterday).  This revision has no particular significance that I know of, but I was playing around with some bug/feature fixes recently made to KiCad, and it was simply a convenient drawing to work with.
  • Added the CAD transcription of the electrical schematics for the flight version of AGC module A15 (drawing 2005265A).
Added the CAD transcription of module A14, in the revisions appropriate for both AGCs 2003993 and and 2003200.  They differ, as far as I can tell, only in the captioning of a single connector pin.  However, the 2003200 revision of the drawing (namely, drawing 2005264A) is quite blurry in the scan, and could stand being checked vs drawing 2005264- (whose scan is quite sharp).    I didn't do that, because I didn't notice at first that we even had a copy of 2005264-, but I did compare it to the also-sharp scan of 2005064F.
Added the CAD transcriptions for the AGC electrical schematics for the flight version of modules A8, 9, 10, 11, 12, and 13. 

If I haven't so commented before, I should mention that for these electrical schematics I've been prioritizing transcription speed — i.e., I'm trying to get a minimally complete set of schematics transcribed and online as soon as possible — relative to accuracy.  So while I think the transcriptions are pretty accurate, and they do all pass KiCad's ERC (automated error check), there are undoubtedly errors in them that will only be caught in proofing directly against the scanned drawings.  And I haven't done a lot of proofing on them.  So, anyone who is interested in participating in such a proof-reading process, feel free to step forward.  Fortunately, unlike the schematic entry process itself, it doesn't involve a lot (or any) knowledge of electronics or electronics design tools to do so, and is simply a matter of comparing two drawings side-by-side.  For example, here are the original scanned drawing and the CAD-generated drawing for module A13 (click to enlarge):

Click to enlarge  Click to enlarge

A good example of the need for proofing is the drawings for modules A8, A9, A10, and A11.  These drawings are so similar to each other that only A8 was actually transcribed, while the drawings for A9-A11 were merely adapted from the drawings for A8.  This sped things up a lot, sure, and it eliminated a lot of potential errors ... but it also masked various other types of potential errors by making it very hard for me to see them.  Proofing will be so important!

As far as the "minimally complete" set of drawings is concerned, I'm referring to AGC p/n 2003200-011 and DSKY p/n 2003950-011, since this is the combination of units for which we can most-plausibly say that we have the exact revisions of all the drawings we need.  Earlier and later AGC/DSKY part numbers will follow, and (I think) will all arguably be close enough to being complete drawing sets as desired for any practical purpose, but not in the mindlessly-obvious sense that 2003200/2003950 is complete.  The reason my earlier comments (below) refer to all of the CAD drawings being added as the "flight version" even though they're for AGC 2003200 is that many of the drawing revisions for AGC 2003200 really are identical to the drawing revisions for AGC p/n 2003993 (the flown AGC p/n), and the ones added so far are among those.  But eventually there will be some drawings added that are close to the flown revision without being 100% identical to them.
Added the CAD transcriptions for the AGC electrical schematics for the flight version of the A7 module.
Added the CAD transcriptions for the AGC electrical schematics for the flight version of the A6 module.
Added the CAD transcriptions for the AGC electrical schematics for the flight version of the A5 module.
Began the process of adding links to the AGC Handbook index to the relevant figures in the various AC Electronics manuals (ND-1021041, ND-1021042) for AGC and DSKY schematics.  In other words, the index will eventually have links to all available schematic drawings from not only the AGC Handbook itself, but for Eldon Hall's set of drawings (as mentioned yesterday), and for AC's redrafted versions of those (or redrafted versions of drawings we don't actually have any other access to).  The latter process is just started, and will take a while, since it turns out to be a lot more time-consuming than I imagined.
  • Added the CAD transcriptions for the AGC electrical schematics for the flight version of the A4 logic module.
  • Updated the AGC Handbook index to include the drawings supplied by Eldon Hall, so that it's more of a master index now.  I hadn't compared Eldon's drawings vs the AGC Handbook side-by-side before, and was surprised to see that in Eldon's set there were only 2 drawings (plus one rev of a drawing) that weren't also in the AGC Handbook.  Of course, there's a very definite difference in legibility in places, so having both sets of drawings is still a pretty nice feature.
CAD transcription of the AGC electrical schematics for the flight version of the A2 logic module was added.  The version mentioned yesterday was an early prototype version of it.
Several CAD transcriptions of AGC electrical schematics were added to the electro-mechanical page, versions of the A1, A2, and A3 circuit modules.  Certain portions of the electro-mechanical page were reworked in accordance to what I've learned by working of the circuit transcriptions.
We now have Volume 1 (of 2) of AC Electronics document ND-1021041.  This document contains, among other things, electrical schematics (as redrafted by AC Electronics to fit into the book) of the Block I AGC.  Volume 2 is coming in the near future.  From the table of contents, it seems that Volume 2 will have most of the rest of the Block I AGC schematics, along with those of the Block I DSKY.  Since up to this point we have had no authentic Block I electrical schematics of any kind, and have been reliant on John Pultorak's reimagining of them, this is a great advance!  Thanks to Ken Mortimer and the Mortimer family for providing this to us.
Sharp-eyed Mike has pointed out a potential (but only potential) versioning conundrum for the model 2003994 DSKY's D7 and D8 modules.  I've changed the comments for them on the electro-mechanical page to reflect those concerns, but don't think any more-substantive change is warranted just yet.
  • Realized how a visual-mismatch between the original scanned AGC/DSKY electrical schematics and the CAD transcriptions of them could be corrected, and did so on all of the drawings that have already been transcribed.
  • Added an Appendix to the electro-mechanical page to cover various issues we've discovered in using KiCad with the AGC/DSKY schematics.  Also, reorganized the electro-mechanical page to be very slightly less confusing.
  • Mike has sent an update to the full (though still very incomplete) MIT part-number list.  Concurrently, I've decided to change the presentation of that list to a table directly on the electro-mechanical page itself rather than as a link to a separate Excel spreadsheet as it was before.  In fact, the master part-number list is now maintained in our github repo, for maintenance purposes, and therefore can theoretically be corrected or extended by someone other than Mike.
  • Hartmuth has sent along a ton more Apollo and Gemini files that he had scavenged from NTRS over the years and that we hadn't already noticed ourselves.  About 130 of them by my count.  So they've been added to the document library.  This caused me to notice a few links to existing docs that were messed up, and so I've fixed those; on the other hand, having added so many new docs at once, I've undoubtedly messed up quite a few of their links, and will have to find and fix those in the near future.
  • It turns out that in all of the drawings so-far converted from the AGC Handbook to CAD (namely, drawings 2005902B, 2005903A, 2005952-, and 2005973r), I had misinterpreted what were supposed to be connector pins as global nets.  Those have all now been fixed.  These schematics now all pass KiCad's ERC (Electrical Rule Checker), with the happy side effect that a few connections which didn't quite "connect" before, due to wire endpoints being physically very close visually but not actually touching, have been fixed as well.  None of this makes a significant visual difference in the images created from the CAD files — mainly, little rectangular boxes with numbers in them have been replaced by little ovals with the same numbers in them — but it's a world of difference electrically and in terms of confidence in the transcription.
  • All of the available drawings from the AGC Handbook for the DSKY module D7 power-supply circuit have also now been transcribed to KiCad, and thus have "pretty" drawings associated with them on the electro-mechanical page.  They actually turn out to all be identical, except that they have different choices of some resistor and capacitor values.
    • Drawing 2005921- (for DSKY p/n 2003950).
    • Drawing 2005904C (for the earlier DSKY p/n 2003985).
    • Drawing 2005904B (a still earlier revision).
    • And finally, a reconstructed drawing 2005937 (for the later DSKY p/n 2003994), using drawing 2005921- and the circuitry found in AC Electronics document ND-1021042 as a guide.  The need for a reconstruction is, of course, that we don't have an actual copy of drawing 2005937 in either the AGC Handbook or elsewhere.
Added transcribed CAD files (and pretty-printed image) for the electrical schematics of the DSKY keyboard module  (drawing 2005903A) to the electro-mechanical page.
  • Made some relatively minor, almost cosmetic changes to a couple of the CAD schematics added yesterday.  But there were pretty important changes to the reconstructed schematic 2005973, since Mike Stewart pointed out that circuit simulations proved that document ND-1021042 was wrong and drawing 2005952 was correct with respect to certain circuit characteristics, and thus I was wrong to trust ND-1021042.
  • Mike had also put together a nice spreadsheet of many (though not all) part numbers for a large number of resistors, capacitors, and so on used in the electrical schematics.  That spreadsheet has been added to the electro-mechanical page.
  • Converted Hartmuth's index into the AGC Handbook pages into an Appendix for our electro-mechanical page, so that it provides actual links to the individual high-quality scans at our Internet Archive site.  Of course, Hartmuth's original index (for the lower-size PDF form of the handbook) is still available.
  • Experimentally (so far), a handful of the electrical-schematic drawings have been transcribed to CAD files using the open-source KiCad system.  These appear in the "schematics" branch of the GitHub repo, and have been added to the electro-mechanical page of the website as well.  The drawings transcribed so far are of all the available versions of the DSKY indicator-driver circuit: 2 versions from the AGC Handbook, plus 1 "reconstructed" but otherwise-missing version that was recreated by combining information from the AGC Handbook and AC Electronics document ND-1021042.  The transcribed drawings are obviously a lot nicer than the 50-year-old xeroxes of the originals, but also potentially contain so-far undetected errors not present in the originals.  You pays your money and you takes your chances!
Hartmuth has also passed along 20 or so documents he had gleaned over the course of time from NTRS, but which we had missed out on somehow, and I've added these to the document library page.  You can just look for the ones marked on that page, since I've also gotten rid of the icon on all docs added prior to this month, so Hartmuth's documents are the only ones currently marked.
Hartmuth Gutsche has gone through the tedium of indexing the entire AGC Handbook, to make it easier to find stuff in it or to see at a glance what's actually in it, and this index has been added to the electro-mechanical page.  Thanks, Hartmuth!  I was going to do it myself, Real Soon Now, but it turned out to much realer much sooner than I anticipated.
The basis for our new electro-mechanical page, first mentioned a couple of days back, is a notebook called the AGC Handbook, given to us by Don Eyles.  This is not so much a "document" as it is (or was) an evolving collection of electrical and mechanical drawings for the Block II AGC and DSKY.  I'm not sure just how many drawings are in the book, but it has around 550 pages, and the drawings average around two pages each.  So ... a lot of drawings.  At any rate, Mike Stewart has finished scanning it, and we now have the complete thing online.  In a slight variation from our usual practice, the document-library page of the website has been bypassed, so a reduced-size (170MB) PDF appears on the electro-mechanical page instead.  As usual, though, the full-quality scans do appear on our Internet Archive page.

It is known that there was a Block I AGC Handbook as well, and presumably later versions of the Block II AGC Handbook covering later versions of the AGC/DSKY, but we don't have any such handbooks.  We never heard of them before Don Eyles broached the subject a couple of weeks ago, and so never even knew to look for them.  If you know of any AGC Handbooks anywhere, please let us know, so that we can try to fill in the remaining gaps in our collection of electrical schematics!
Added to the document library page a couple of portions of documents sent over by Don Eyles and scanned by Mike Stewart.  These are drafts of Section 3 of volumes 1 and 2 of the AS-278 GSOP, namely the "Block II GNC System Description" and "LEM PGNC System Description", respectively.
Added some nice images and numerous drawing numbers (but sadly, no actual drawings) to the Block I tables on the electro-mechanical page.
Various additions and corrections to the electro-mechanical page, but mainly there were three DSKY drawings which we've managed to locate, so the Block II DSKY electrical schematics are much more correct than yesterday.
The minimal treatment given previously to AGC electrical schematics has been replaced by a much expanded treatment on a page dedicated to AGC/DSKY schematics and mechanical drawings.  A lot of AGC schematics we never had before have been added to it.  This is just the first draft, though, so there's a lot more work to do on this new page, and on filling in more of the previously missing data.
  • As students of AGC assembly language know, the AGC language is actually an intermixture of pure machine code (called "basic" instructions) and higher-level instructions ("interpretive" instructions) that are executed on a built-in interpreter which is itself is written in basic instructions.  In an AGC program such as LUMINARY or COLOSSUS, a sequence of interpretive instructions is marked by the fact that it begins with the basic instruction TC INTPRET (to start a block of interpretive code) or TC DANZIG (to return to interpretive code from a basic-instruction subroutine called by interpretive code);  other basic instructions precede the TC INTPRET/DANZIG, while interpretive instructions follow it.  All very well and good ... but while INTPRET is clear, whyDANZIG?  Danzig is obviously (or was obviously) the name of a city in Poland, but is that significant somehow?  Since this is the kind of thing I worry about, I've wondered about it since the beginning of this project, about 15 years ago.  But on that issue, today is the day to stop wondering! I now know why, and you can know why too, if you follow this link to the explanation I've added to the assembly-language page.
  • Enthusiasts may also recall that Hugh Blair-Smith has graced us with his preliminary notes on what an improved AGC architecture, which he terms "Block III", might look like.  Well his thinking on the subject, upon which he has been working with Bruno Muller, have advanced a lot in the couple of years since we last heard anything about it.  Naturally, I've posted the current thinking on this subject on our Block III page.
Added a favicon for the web-pages.
  • 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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