Unfortunately, the aperture-card scanner broke down a couple of weeks ago, and I'm not privy at present to the proposed scheduling for getting it fixed. Actually, what with the intervening Holidays and various other coincidental conditions, I'm not even sure that the scheduling has been addressed yet at NARA. Well, it'll be fixed when it will be fixed, and for now we'll have what we'll have. In the interim, I'm hoping to go back and scan (with a different, slower scanner) the drawings which proved partially or completely illegible on the first attempt. That's about 400 scans. But again, we'll have to see.
- Added engineering-drawing titles and marked illegible scans in LEM aperture-card box 509.
- I've noticed somewhat belatedly that our Virtual AGC
home page, which brags quite a bit about — excuse me, I
mean humbly mentions, almost as an aside — the various
materials the project provides, failed to mention the
LEM engineering drawings. I've corrected that
oversight.
- The engineering-drawing titles for LEM aperture-card box 506 have been added. I've also started inventorying and marking scans which are too illegible for one reason or another (usually due to being too light to fully read), so that's been done here as well.
- Retroactively marked the illegible scans in LEM
aperture-card box 503, to which I had previously added
the titles a week ago, as well as finding/fixing an
incorrect drawing number or two that I missed on the
first pass through the box.
- A table of 50 or so LEM engineering drawings that was previously gratuitously stuck at the end of the page for miscellaneous G&N engineering drawings, for lack of a better place to put it, has now been removed to its own dedicated page for miscellaneous LEM engineering drawings. I suppose this reorganization doesn't need any serious justification ... nevertheless, it was done because I now recognize the need to eventually rescan a fairly significant number of LEM aperture cards whose initial scans are not legible enough. The new miscellaneous LEM page will be a good place for those rescans to live.
- Although there will be no "search engine" for the LEM engineering-drawing scans like the one for the G&N scans — simply because the search database would be too big to reasonably load into a browser with the current situation vis-à-vis network bandwidth, computer memory, and so on — I've belatedly realized that there's no reason I can't provide such an index as a non-browser file that you can explicitly download, load into a spreadsheet, etc. So I've added a master LEM engineering-drawing index file. I expect this file will eventually exceed 60MB in size — which should give you some idea why I don't think you'd want to load it into your browser — though right now it's in the neighborhood of just 2MB. Since the project of scanning the LEM drawings and indexing them is ongoing, the master-index file is naturally a work-in-progress as well!
- Added the titles for engineering drawings in LEM
aperture-card box
505.
- Added the scans of LEM engineering drawings from
aperture-card Box
508.
- Added the engineering-drawing titles in LEM Box 503.
This is the first LEM box whose title-addition has been
completed (though Hartmuth is working on Box 502 as
well), and as such is likely to have some teething
problems ... but whether or not that turns out to be the
case, it's still a lot better than having no
titles. A handful of drawing numbers and/or titles
are missing or partial for a variety of reasons, such as
the scan just being too light or the sheets containing
the titles being in aperture-card boxes that haven't yet
been scanned. So expect there will be still be
some improvements in that area in the coming months or
years as additional scans dribble in.
I've had second thoughts about my earlier comments, wherein I said that I wouldn't bother to index any of the LM drawings, and have decided to go ahead and provide a dedicated index page for each box of LM drawings. Nevertheless, for technical reasons it's still the case that I don't intend to add any of these LM drawings to the master engineering search engine or to provide assembly drilldowns. So the drawings will still be a trifle trickier to access than the G&N drawings in some cases. At any rate, the first couple of boxes are now available, namely Box 502 and Box 503. We won't be reaching the drawing-number range containing the top-level drawings for the LM until boxes 518 through 528, though, which hopefully will happen sometime in January 2020, depending on the breaks. Due to the fact that the metadata for the LM drawings is completely different in form from the metadata I was working with for the G&N system, the process of creating these indices is very much a work in progress that will undoubtedly experience a few initial hiccups.
Unfortunately, the drawing metadata (drawing number, revision code, etc.) on which the box-index pages are necessarily based turns out to be incorrect much more often than I've been accustomed to in the earlier (G&N system) scans. There are dozens of such errors in boxes 502 and 503 alone. The usual error is an incorrect drawing number. Thus it is often the case that due to being mislabeled, a drawing may not only be in the wrong position in the index table for any given box, but may even be in the wrong box entirely. I've made an attempt at correcting these, but given the vast number of scans involved, there's just no way I can do it whilst still performing scans of additional boxes. In other words, I had to give up pretty quickly. Perhaps they can be corrected in the future ... perhaps by someone much more interested in the LEM drawings than I personally am. (Hint!) But don't hold your breath waiting for me to do more than a handful of them myself.
Possibly even worse, the aperture-card punch-data doesn't list any of the drawing titles at all, not even the abbreviated titles as the G&N punch-card metadata did. So at present, all (or almost all) drawing titles are simply listed as blank. Over the course of time, perhaps, those drawing titles can be manually added to the index pages. (Again, hint! Hint!!) As a rule of thumb, I'd say that any entries having a non-blank title in the index have also been double-checked or correct insofar as their other metadata.
That doesn't mean the work on these G&N drawings has finished. Many of the indices for the boxes still need to have their drawing titles corrected to agree with the drawings' title blocks (as opposed to the aperture cards' punched metadata), and many assemblies represented by the drawings still need to have their bill-of-material information digitized to allow accurate assembly drilldowns; plus, those electrical drawings being transcribed to CAD still need transcription. Nevertheless, the initial work of physically scanning the drawings has finished, and the remaining work on them can proceed without regard to physical access to the archives.
It also doesn't mean that scanning is complete, either. While scanning of guidance & navigation drawings has finished, many additional (non-G&N) unscanned boxes of aperture cards remain. The next step is to scan Grumman's LM engineering drawings, boxes 241-333 and 502-688. A quick calculation shows that there are 280 LM boxes (over 500K scans) vs the 47 G&N boxes (90K scans) ... so it may take quite a while. There are additionally many hundreds of North American CSM boxes, but I'm not currently planning to scan any of those personally; I have reason to believe they may eventually become available via other mechanisms without any intervention be me (thank goodness!), but "eventually" is a rather open-ended concept in this case.
Incidentally, box 477 contained a group of drawings (over 500 of them) not conforming to the pattern of the other G&N drawings. The group included such things as IRNs (Interface Revision Notices) and TDRRs (Technical Data Releases or Revisions). Right now, it's hard for me to deal with these anomalous drawings in the same kind of context (i.e., master engineering search engine or aperture-card box index pages) as the other drawings. As a result, instead of including them on the box 477 page, I've segregated them onto a separate "Additional Engineering Drawing" portal, from which you can still view the scan without any expectation of them being pre-digested by me. Several other groups of anomalous drawings (from boxes 431 and 472, and elsewhere) have been included on that portal as well. I expect that the Grumman LM drawings whose scanning will commence soon will be handled in that same way, simply because it would be incredibly time-consuming for me to treat them comparably to the G&N drawings. In other words, I'm willing to scan non-G&N drawings, but not to fuss with them endlessly. That will be left as an exercise for the reader.
My short-term goal is to finish scanning all of the Apollo G&N boxes (i.e., through box 477) by November 21, which is the last day the U.S. government (and hence the National Archives) is funded. In other words, if the government shuts down on the 21st, then scanning will be impossible for the duration of the shutdown. Personally, I think a shutdown is highly likely. News reports, on the other hand, are so far discounting that possibility. Well, we'll see; I'd be happy to be wrong. At any rate, after box 477 is scanned, then scanning of the (hopefully!) complete set of Grumman Lunar Module aperture cards will commence. I expect that process to take the next couple of years.
- Completed adding Apollo G&N engineering drawings from aperture-card box 456 and added about the initial 60% of box 457. A handful of additional assemblies were also added to the assembly drilldowns.
- Modified the instructions for building Virtual AGC on
the Raspberry Pi for the latest version of the operating
system (Raspbian Buster).
- Completed scans of Apollo G&N engineering drawings from aperture-card Box 448.
- Added complete scans from Box 449.
- Added scans of the initial part of Box 450.
- Regenerated engineering-drawing
search engine and G&N
assembly drilldowns.
On a more-positive note:
- Several new MSC internal notes (64-FM-55, 65-FM-57, and 64-FM -74) were added to the Gemini section of the document library. They relate to algorithms (with flowcharts) for computation of trajectories. Though these were written for Gemini, they apparently remained the gold standard for Apollo, and are referenced in some of the Apollo docs recently added to the library.
- Scans for NARA-SW aperture-card Boxes 431 (partial), 432, 433, 436, and 437 have been added to the collection of engineering drawings. Box 431 is particularly notable because it contains a number of Rework Instruction Bulletins (RIB), of which very few have been available previously. Box 431 also physically contains a few dozen Interface Control Drawings from North American Aviation, but because these follow a different numbering convention than all of the MIT/AC/Ratheon/etc. aperture cards scanned so far, I have not yet worked out how they should be processed or presented, so I've not yet made them available online ... which is the reason that Box 431 is listed as being only "partial". Besides that, because of the bulk of scans that have been added (~9000 microfilm slides), I've not had the opportunity to fix up the titles of most of the drawings. For now, most of the titles just show up in the index in the 21-character abbreviated forms punched into the aperture cards. I'll fix them up some time, but it's an ongoing process and I won't promise any specific time-table.
Note that while the newly-added engineering drawings have
been used to update the
drawing-index page and the
various assembly drilldowns for different G&N System
configurations, the latter have only been partially
updated because their bills-of-material have not yet been
transcribed ... i.e., newly added assemblies are
not yet drilled down. The additions to the
drilldowns have the most impact on Block I G&N
Systems, but all Block II and LM G&N Systems have been
affected to one degree or another as well.
- NARA-SW aperture-card Box 434 has now
been scanned. This box contains just a handful of
items (though with lots of revisions and pages each), so
I'll list them all here. They're all Apollo
guidance & navigation system checkout procedures for
various spacecraft:
- Document ND1002323 (revisions J and later), for the
LM, running AURORA software.
- Document ND1002324 (all revisions), for the Block I
CM (specifically, CM-014), running SUNSPOT
software. According to this document (p.
15), CM-014 was used only for testing and was
eventually scrapped in 1977. Since the CM was
never used for anything other than testing, it's
entirely possible that its AGC still had SUNSPOT ropes
in it when the CM scrapped, and thus it seems possible
that that Block I AGC (or its rope-modules separately)
are still floating around somewhere. In other
words, SUNSPOT may be recoverable by dumping the
contents of those rope modules, if they (and/or their
AGC) are ever found. Unfortunately, I neither
know where the AGC nor its rope modules are, nor do I
know of anyone who has successfully dumped the
contents of Block I rope modules. I wish I did.
- Document ND1002325 (revisions W and earlier), for the Block II CM, running SUNDIAL C or D software.
- Similarly, the first half of NARA-SW
aperture-card Box
433 has also been scanned. It contains many
more documents than Box 434, so I won't list them all
here. They are principally process specifications
and testing procedures. The most-notable document,
I think, is ND1002319, "ACE-S/C Computer Subprogram
Specifications for Apollo CM and LM G&N Testing",
but only through revision L. (Revisions through U
will be in the second half of the box, not yet
available.)
- There has been a document talking about something called "SIMFAM" in our document library for a quite a while. This is a memory adapter for the AGC, for ground testing, based on something called "braid memory" rather than core memory. Unfortunately, I was unable to find out much about braid memory myself, but Nikki Stevens (thanks, Nikki!) has now sent me some info about it, and I've naturally incorporated an explanation into my descriptions. (Alas! The info comes from a 1966 IEEE paper, which I fear is still under copyright even though not so marked, so I don't post the entire paper.)
- Various new documents have been added to the document
library, most of them newly scanned (so their
full-resolution scans are in our Internet Archive site
in addition to the low-resolution links below), although
the first one on the list below actually came from NTRS:
- 68-FM-256, "Project
Apollo: Verification of Sundisk Orbital Navigation
Program". This actually contains a lot of
software-related technical detail about SUNDISK 282,
the Apollo 7 flight program. (Thanks, Nik Beug!)
- 68-FM61-230, changes to 68-FM-23, "Logic and Equations for the Real-Time Computation of the Lunar Module Descent Planning Table" (which was already in the library).
- 68-FM-67, "Logic and Equations for the Real-Time Computation of the LM Launch Targeting and Display".
- E-2456, "Apollo Guidance and Navigation Flow Charts":
- Rev. 1, Program COLOSSUS 2D, COMANCHE 72 (full document).
- Rev. -, Program COLOSSUS 2C, COMANCHE 67 (just the flowcharts changed from COMANCHE 72).
These were the first and second revisions of LUMINARY targeted for the Apollo 14 mission, and their memory modules were manufactured but not flown. (Instead, LUMINARY 178, the final released version, which Mike managed to finish reconstructing a few days ago, was actually flown.) So in just a few days, we've gone from having essentially nothing for the Apollo 14 Lunar Module, software-wise, to having pretty much everything you'd ever need to know!
It probably goes without saying, but beyond just their intrinsic interest on their own, having the complete set (163 & 173 & 178) further increases our confidence in the reconstruction of each of them individually. That's because the reconstruction of 163 is based on 173, while the reconstruction of 173 is based on 178. We have confidence in the reconstruction of 178 because its checksums are correct ... but there's a small though non-zero chance that an incorrect memory bank could still have a correct checksum. However, it's still unlikelier that you could modify an incorrect memory bank (from 178) having a correct checksum and somehow obtain another bank (from 173) that also had a correct checksum, and then modify that bank again to get still a third bank (from 163) having a correct checksum. Admittedly, that argument doesn't apply to all of the memory banks in the program, since not all of them needed to be reconstructed for each of these software revisions, but it applies to enough of them to give us a good feeling that the reconstruction process does exactly what we hope it's doing.
- Mike Stewart has managed a true tour de force,
by reconstructing and contributing the reconstructed LUMINARY 178
source code. LUMINARY 178, you may recall is the
LM's AGC program for the Apollo 14 mission. It has
been a sore spot for me for a while, in that we've had
the LUMINARY code for all other flown missions —
i.e, Apollo 10-13 and 15-17 — for a long time ... but
not Apollo 14. It has been the only one
missing. This is quibbling a little bit, I admit,
since it ignores Apollo 5 and Apollo 9. But
technically those missions didn't use LUMINARY; Apollo 5
used SUNBURST (which we have!) and Apollo 9 used
SUNDANCE (which we don't!). So I guess the missing
SUNDANCE will now become the sore spot. But I
digress. Finally filling in the gap for Apollo 14
is great no matter how you look at it, but what makes it
a tour de force, is the vast gap that
this fills in terms of software changes. The
Apollo 13 and 15 LM software were LUMINARY 131 and
210, respectively ... that's 79 revisions in between,
with Apollo 14 being smack dab in the middle.
Amazing! So the reconstruction requires figuring
out the changes for something like 30-50
revisions. Getting to the end of that process is
like finding the missing link. It makes the slogan
you see in the website logo ("Apollo Digital
Archaeology") seem quite appropriate. Not only is
the code in
the software repository now, but support for it
has been added to the VirtualAGC GUI.
- On a lesser note, I've finally finished proofing the LVDC source code's program
comments. Experience suggests there are still
quite a few errors I missed. Nevertheless, given
that the code has been proofed, and assembles to exactly
the expected core-rope image, I'm finally willing to put
my stamp of approval on it and say that it's
"ready". If only ITAR concerns allowed me to
freely provide it to you .... Sigh!
Well, a lawyer's working on it, and will perhaps
discover that the ITAR fears are overblown. Or
not. At any rate, you can still apply to me on an
individual basis to get the code if you're a "U.S.
person" under the law. Next step:
simulation.
icon on the document-library page),
but the one that particularly stands out for me is
Raytheon's 1969 "Final
Report: Apollo Guidance Computer Program Block I (100) and
Block II". Don't be confused by the title referring to
the "program", since the report is not about
software. The report is a nice way of getting a
pretty-detailed understanding of all the different hardware
Raytheon produced for the program, including all the AGCs,
DSKYs, and associated ground-support equipment, which is
pretty hard to get piecemeal from other documentation.
I was particularly enamored of an exploded diagram for the
Block II DSKY that I don't recall having seen before,
to the extent that I even pulled it out of the report and
added it to the DSKY page.
I'm sure there's nothing in the diagram that you can't get
already from the many DSKY engineering
drawings we have, but it may be useful for those of
you who have been working on constructing your own DSKYs.When I say it's incomplete, I don't mean that there are pages missing from the program listing, or anything of that nature. The Flight Program listing we have is completely self-contained, and can be assembled without error ... or at least could be assembled without error if a handful of undebugged problems in this engineering (as opposed to released) version of the code were fixed.
No, what I mean is that the Flight Program was not the only program that needed to be loaded into LVDC core memory to get a complete working system. At the present time, I believe that the missing program would have been the Preflight Program. The Flight Program and Preflight Program would have interacted via certain addresses hard-coded into those programs. Unfortunately, right now, when the Flight Program calls routines that are supposed to reside at those addresses, there's simply nothing there, and chaos would ensue.
For example, I think that one thing the Preflight Program probably had was the self-test routine. Very handy! And very unhandy not to have it. By the same token, a self-test routine is hardly essential to the operation of the system, and it might be possible to make the Flight Program happy simply by sticking some kind of relatively-simple replacement for it at its specified hard-coded address. And all of the other problematic addresses I've seen similarly relate to code that might be painlessly worked around. But I don't have a complete survey of all the offending missing code, and can't really make too positive a claim at this point. Time will tell how serious a problem this turns out to be.
As usual, I've written all this up in more detail on the LVDC page itself.
- Added a copy of the Apollo 11 Operations Checklist to the document library. This was already available at the Apollo Flight Journal, so please feel free to examine there instead.
- Scanning of the final half of aperture-card Box
435 from NARA SW has now been completed.
This batch contains "post-installation checkout
procedures for the the G&N system. The rate of
scanning aperture-care boxes has slowed down somewhat
recently due to circumstances, but is due to pick up
again to a much higher rate in the near future.
- More updates to descriptions of LVDC assembly language, AS206RAM program structure, and so on.
- It turns out that my instructions for downloading
a Virtual AGC "installer" for Windows may have
been a tad thin in terms of explaining how to actually
run the program once it has been downloaded. So
I've pepped up that explanation to make it a lot more
explicit.
- Manoel has submitted a couple more 3D models, 2004739A-000 and -021, DSKY front cover. This is significant because it turns out that model 2004929 (also DSKY front cover) added a couple of weeks ago was not the one called out for DSKY model 2003994-121 at all, and that 2004739 is what should be used. This was not just an oversight, though! The problem is that drawing 2004739 simply isn't dimensioned very thoroughly, whereas 2004929 is dimensioned quite thoroughly, so the hope was that 2004929 would be a good substitute. Alas, it was not! Some of the dimensions (specifically the width and height of openings for the indicator lamps) from drawing 2004929 are not compatible with the other constituent assemblies in DSKY 2003994-121. Thus while the new models for 2004739 are intended to be exact representations of the original drawing, there's not enough detail on the original drawing to insure that; so the new models contain both elements from 2004929, as well as measurements which were fortunately able to be gotten from a physical 2004739 module. Nevertheless, the potential for error remains and thus the models may need to be further adjusted over time.
- 10 new document scans from NARA SW have been
added. Many of them relate to RTCC software
flowcharts for various Apollo 14 G&N computations,
and to GSOP changes from Apollo 13 to 14. Rather
than enumerate those documents here, I'd suggest looking
for the icon on the
document-library page.
- Corrected my confused description of LVDC instructions HOP*, TRA*, TMI*, TNZ*: I've belatedly realized that there should be no such instructions in the LVDC source code, and that the asterisks are added in the assembly listing to highlight that certain workarounds have been transparently performed.
- Manoel has added a few more 3D
models for DSKY parts. It should be noted
that the first two of those models listed below are
created from the external dimensional properties
of "Specification Control Drawings" (SCD). That's
significant because the these assemblies were
manufactured independently, and while they are really
themselves assemblies, the internal characteristics of
the assemblies are (well, were) known only to
the manufacturers of the assemblies. In other
words, there are no available drawings describing their
internal structures. Consequently, you can't
simply 3D print them and expect that they'll do anything
for you, particularly since they contain circuitry not
represented by the 3D models. They'll need to be
reverse engineered in order to reproduce their
electrical and behavioral characteristics. The
third model is also problematic, because we don't have
the latest revision of its original drawing.
That's significant, because most DSKY's specify use of
configuration -001 of the part, while the most-recent
drawing we have covers only up to configuration
-000. Consequently, the 3D model also conforms
only to configuration -000 rather than to the necessary
-001, and therefore also likely requires modification.
- 1006315A, electroluminescent digital indicator
- 1006387D, alarm indicator
- 2004699A, indicator frame cover
- Manoel has added a few more 3D models for DSKY parts. I forgot to mention yesterday that these are parts for DSKY model 2003994-121 (the final CM DSKY model), though the parts Manoel has submitted so far seem applicable to all Block II DSKY models I've checked so far. (Admittedly not every single one!) I probably should have mentioned too that the models being added so far are intended to precisely capture the original Apollo engineering drawings, and hence do not include any optimizations for (for example) 3D printing; alternate 3D models with such optimizations may be added in the future. Also, for those who haven't stayed atop the behind-the-scenes discussions, it's perhaps useful information that the models are in STEP format, which can be imported into most 3D modeling programs, but specifically into the open-source FreeCAD modeler. I probably should summarize what those parts are, too, rather than forcing you to figure it out for yourself. Here's the complete list so far:
- 2004900A, rear cover
- 2004919E, adapter plate
- 2004920-, digital indicator connector plate
- 2004921A, alarm indicator connector plate
- 2004929A, front cover
- 2004968E, front housing
- Mike has confidently reconstructed yet another AGC software version, this time Artemis 71. As you may recall, Artemis 72 is the software actually flown in the Apollo 15 through 17 Command Modules. But Artemis 71 was originally intended to do so. Artemis 72 flew instead, because of a bug fix. As with all these software reconstructions that have been appearing lately, we have no actual assembly listing of Artemis 71 to work from. Nevertheless, the clues present in the Artemis 72 assembly listing, in concert with the Artemis 71 memory-bank checksums (which we have from engineering drawing 2021154), allow us not only to infer the required changes, but to verify them afterward. Great work, Mike! The VirtualAGC GUI program now supports Artemis 71 as well, so you can run Artemis 71 or browse its source code in VirtualAGC if you like.
- The
Apollo G&N system assembly drilldowns now
include links to the appropriate 3D models of the
associated parts wherever possible (similar to the way
they have already been including links to CAD
transcriptions of associated electrical schematics).
- Reworked a lot of the discussion of LVDC assembly-language coding, on the basis of my improved understanding of it, and particularly an explanation of the LVDC preprocessor.
- We've had our first submission of 3D models to our mechanical-drawing repository, for some DSKY parts. They look pretty swell to me. Thanks, Manoel da Silva Casquilho!
- Unfortunately, Manoel had to deal with some pretty
poorly-written instructions in so far as the
requirements on the 3D models, as well as practically
non-existent instructions on how to actually submit them
to the repository, so I've rewritten quite a lot of the
section on our electro-mechanical page describing
that stuff. Hopefully it's better, but knowing
myself I can't claim to be 100% confident that it is.
- A handful of documents added to the library a few
weeks ago have now been removed. Well, perhaps a
handful and a half. For the most part, I've done
this by expunging the files themselves, but leaving the
hyperlinks on the document library
page and striking them out (
thusly) so that it's easy to see what has been removed. These documents originally came from NTRS, but were removed from NTRS when it was decided by NASA that they hadn't been approved for release; so now they've been removed from Virtual AGC too. Sweet! I don't actually know if it was necessary to remove them, but it has been done as a precaution. Of the 1000+ documents we provide, who knows how many have thus been (or will be) taken retroactively out of the public domain, with no practical way for us to even know about it or react to it? (Hint: We don't.) Can you spell "time bomb waiting to go off"? (Hint: You don't have to. I just spelled it out for you.) Or perhaps, "closing the stable door after the horse has bolted"? (Hint: Ditto.) For what it's worth, I think the documents are available on The Wayback Machine's cache of NTRS, if you can figure out how to find them, and with luck perhaps they'll return here at some point.
- Speaking of secret knowledge, I've finished my first
pass at transcribing the LVDC AS-206RAM assembly listing
to source code, but am afraid now to post it publicly
because of ITAR and the danger that North Koreans may
start pelting us with Saturn V or Saturn IB rockets if
they get hold of this 50-year-old software
listing. (The projected cost of a Saturn V
in 2019 dollars is around $726M, but that of a Saturn
IB such as would have been used for the AS-206RAM
mission is probably only around $220M. A bargain,
to a thrifty hawk! To be fair, when I wrote those
sentences, they were intended to be biting sarcasm, but
given that LGM-118
Minuteman ICBMs would cost perhaps $110M in 2019
dollars it doesn't even seem that far-fetched that some
nut-job would spend $200M for a Saturn IB as an ICBM,
does it?) Fortunately, anyone (who can prove
they're an American) can naturally apply directly to me
to get a copy of the transcribed software.
However, you might want to wait until it's decently
proofed first and the assembler itself is ready.
- Mike has added yet another AGC software reconstruction, this time of the Comanche 51 source code. Comanche 51 was the program that was first targeted for the Apollo 11 Command Module, though it was Comanche 55 that eventually flew in the mission. Reconstruction of all these intermediate AGC software versions may strike you as merely an intellectual game, which I suppose it is in some ways, but it has serious benefits as well. For example, I'll remind you that a few days ago we got the Luminary 69/2 reconstruction, and this was actually mission software (for the Apollo 10 LM) that we hadn't had originally. In the case of Comanche, the Holy Grail would be reconstruction of Comanche 45/2, which is the missing mission software for the Apollo 10 CM. Having Comanche 51 rather than just Comanche 55 gets us that much closer to the goal. Even so, getting from Comanche 51 to 45/2 is quite hard, since we don't have the level of supporting documentation for Colossus that we do for Luminary. A reconstruction of 45/2 would be ever so much easier if Margaret Hamilton just gave us her copy of Comanche 44 ... though that, sadly, seems less likely with every passing year. But we'll see what we'll see!
- The
G&N assembly drill-downs are once again
up-to-date with respect to all of the
engineering-drawing scans (and CAD transcriptions)
collected so far.
- Mike has added reconstructions of the Luminary 97 and 98 source code, following the same procedure as for the Luminary 130 and 69 rev 2 reconstructions over the last couple of days. There's slightly less confidence in the Luminary 98 reconstruction than in the 97 reconstruction, since back in 1969 Luminary 98 was just development software en route from 97 to 99, so its ropes were never manufactured nor its memory-bank checksums recorded. However, if Mike's Luminary 98 reconstruction were in error, his 97 reconstruction would probably be in error as well ... which is unlikely since all of its memory-bank checksums are correct! In other words, while we're less confident of the Luminary 98 reconstruction than in the 97 reconstruction, we still have a pretty high degree of confidence in it.
- On our Luminary page, I long ago hyperlinked the raw
scans of AGC assembly listings stored at our Internet
Archive site. But in some sort of strange mental
conniption, I belatedly find that I never did that on our Colossus page! I
guess it's because so much data was pouring in from Don
Eyles at the time that I was thinking only about the
Lunar Module and not about the Command Module at
all. Well, I have finally taken care of it now!
- Mike has added a reconstruction
of the Luminary 130 source code, following the
same process as for yesterday's reconstruction of
Luminary 69 rev 2. Admittedly not quite as
exciting as yesterday's reconstruction if you're only
interested in software actually flown. On the
other hand, it is becoming increasingly obvious that the
more software versions we collect the easier it is to
fill in the gaps between them, so it's nothing to be
pooh-poohed by any means! (Excuse me, I mean
P00H-P00H'ed.) Plus, various Apollo 13 documents
referenced Luminary 130 anyway, and were never revised
for 131, as far as we know.
- The VirtualAGC GUI program has been updated for both
Luminary 69 rev 2 and for Luminary 130.
- I've adjusted the size of the youtube video thumbnails I've embedded in the tables on the Luminary and Colossus pages, since I notice they were so big that when the windows were made smaller the text overflowed to the right and needed scrollbars to see. I can't get rid of this effect entirely, but making the thumbnails smaller mitigated it somewhat.
- On the FAQ page,
I've added links to Ken Shirriff's writeup of his
article about bitcoin mining on the AGC, as well as to
David Given's writeup of his port of his Cowgol
programming language to the AGC, as well as the
subsequent creation of a lunar lander game (Cowlark)
written in Cowgol. In other words, Cowlark is a
lunar lander game which can be run on the AGC. Fun
stuff, though I'm not sure programming in Cowgol
actually gives you "the AGC programmer experience".
That's were some of the engineering drawings I (my sole contribution to this discussion!) scanned a couple of days ago come in. These drawings, 2021151 through 2021154, astoundingly list all of the memory-bank checksums for lots of AGC programs ... including lots of revisions of programs that we don't have. This information, which may seem rather pointless on the face of it, actually opens up the door for reconstructing a lot of software revisions we don't have. Why? Well, we do have source code for an increasingly-large number of Luminary and Colossus software revisions, and we often have LUMINARY Memos or COLOSSUS Memos that tell us in a descriptive way which changes were made between successive revisions of the software. This is especially true for Luminary. Thus from the descriptions of the changes, we can attempt to back-port those changes (as observed in later revisions of the software) into earlier versions of the software and then check if those changes produced the proper memory-bank checksums! We've done this in the past in the handful of cases where we knew the checksums of unavailable software revisions, but we never had such checksums for a large number of missions to work with before.
In the case of Luminary 69 Rev 2, Mike Stewart has stepped in and reconstructed it overnight, using exactly the method described above. Thanks, Mike, once again! So while yesterday we had Apollo 10 LM software that was "close enough", today we are pretty sure we have the exact software used in the mission.
- Added G&N engineering drawing scans from NARA SW
aperture-card boxes 467 (final 2/3)
and 435 (first
half). Box 435 contains a lot of G&N
system post-installation checkout procedures from North
American Aviation. It has been scanned out of
order because some of the procedures relate to using
SUNDIAL. Another notable procedure therein uses
SOLARIUM for checking out the Block I systems for Apollo
4 and 6. All index pages and the
engineering-drawing search engine have been updated, but
the assembly drilldowns have not yet.
- Added three new documents to the library (thanks, Graham!) concerning AS-503A (an unflown alternative mission) and Skylab.
- Replaced the LVDC software sample images with higher-quality ones of the same pages.
- Don Eyles has sent along some scans of two data-card
booklets: an earlier one for the Retread
50, Aurora, and Sundial B & C software, and a
later one for just the Aurora 88
and Sundial C software. Since Aurora and
Sundial were used for checkout of the LM and CM guidance
systems, respectively, I infer from that Retread must
also have been used for system checkouts at some point,
but was then obsoleted. As usual, the full-quality
scans are at our Internet Archive site. (Thanks,
Don!)
- Yesterday's edition of The Orbital Mechanics podcast is an interview with me, talking about the Virtual AGC project. It sounded good in my head when I said it, so *cough* *cough* it must be good on the podcast too!
- A few more miscellaneous documents have been added to
the library (thanks, Graham!). Just look for
the icon.
- It turns out that my comments yesterday about SUNDIAL D vs SUNDIAL E in the 2TV-1 mission were misguided. What I should have been saying was that the fixed-memory modules (which are what holds the SUNDIAL program) were different than what what the engineering documentation led us to believe: specifically, if you're interested, MIT's AGC contains software assembly 2021104-051 rather than the 2021104-041 we expected. However, Mike has managed to find documentation that both of those assemblies held SUNDIAL E software anyway, so it hardly matters which one was installed in the computer. Thus I can happily contradict what I said in yesterday's entry: We truly do have the software for the 2TV-1 mission! I've altered the description on the COLOSSUS page to reflect that fact.
- The VirtualAGC GUI program has now been updated (at GitHub) to have the 2TV-1 mission as one of the options.
- Added a series of documents (thanks, Graham Donald!)
to the library, concerning potential applications of the
LM. Also, quite by chance, I found a grayscale scan of document
R-700 online that's fantastic, compared to the
B&W scans we already had, because you can actually see
the photographs; naturally I snatched it and stuck it in
the document library too.
- Much like with the RETREAD 50 AGC software we added a few weeks ago, the AGC Restoration team has now dumped the rope memory from the MIT Museum's AGC and has given us the AGC program SUNDIAL E. This is our first look at SUNDIAL. SUNDIAL E is close to, but presumably not exactly the same as, the SUNDIAL D software used for the 2TV-1 mission, so that's how I've categorized it on our COLOSSUS page. In a larger sense, I think that SUNDIAL was generally used for system checkout of Command Modules, much as AURORA was for Lunar Modules. We don't have the source code yet, since the restoration team has been so busy, but presumably Mike will churn it out for us in the reasonably-near future by comparing to similar program versions and judicious disassembly. The binary is apparently ready-to-run in yaAGC, though I have not made the necessary changes yet to do so within the VirtualAGC GUI environment.
- At the same time, 3 out of the 6 rope modules for the
program SUNDANCE 302 were dumped, and have been added to
the
GitHub repository. I've not written up
anything about it on the LUMINARY page yet, though,
because I haven't figured out yet how to go about
describing half of a program. The idea, of
course, is to try and find the other half of it later.
- In thrashing out whether SUNDIAL E was or was not used
in 2TV-1, it became apparent that some of the
compatibility tables in documents ND-1021042 and
ND-1021043 could be used to fill in a couple of
missing-link engineering drawings related to
configurations of SUNDIAL and AURORA, so I've now done
that and regenerated the assembly drilldowns of the
engineering drawings accordingly.
- Added another couple of documents to the library, this time peripherally related to Apollo 13. Incidentally, I was remiss yesterday in not thanking Graham Donald for sending these docs over to me.
- Yesterday's edition of The London
Podcast by presenter Adrian Lacey, among other
things features me talking about the Virtual AGC
Project.
icon.As I explain in more detail on the LVDC page, we are not certain yet about the ITAR status of this assembly listing: Maybe ITAR restricts who the program can be given to ... and maybe it doesn't. I kind of think it doesn't. I hope we'll eventually find out for sure that it doesn't, and I'll then be able to post the scans online. Unfortunately, until/unless the legal issue is resolved, it's a close enough call that I'll have to assume by default that ITAR does restrict access. So if you want the scanned program listing, you'll not only have to
I've also done a preliminary pass on looking through the listing and have written up all my observations and inferences about the the syntax and pseudo-operations of LVDC assembly language, as well as about the AS-206RAM program itself. That's a prerequisite for getting a working LVDC assembler, which along with transcribing the listing's source code is hopefully the next step. (And no, sorry, once I have transcribed the source code, it won't be freely distributable either until ITAR questions are resolved for the better.)
- More page images of the 1967 LVDC flight program have come in. I've had to reorganize the underlying storage of these items a bit by taking the LVDC page images out of the GitHub repository. Otherwise, if new images kept coming in — something of which there's no assurance whatever — they'd begin to overwhelm it. But the change should be completely transparent to anyone looking at the website.
- Added my
analysis as to whether the LVDC software is classified
or as to whether it is illegal under ITAR to "export"
it posting it online. The executive summary
is "no" to the former and "maybe yes, maybe no" to the
latter. Anyone with a better understanding of the
legalities related to this than I am ... please
pass along your wisdom to me!
- Updated the description of the LVDC's TLC interrupt with a bit of anecdotal info.
- The description of the LVDC's STO instruction was shockingly deficient in terms of how it covers subroutine linkages — namely, it didn't, and indeed provided misleading information — so I've fixed it up.
- I've added a
lot of descriptive material about what I infer (or
more politely, guess) from the LVDC sample code
about the syntax of LVDC assembly language. This
is particularly true for the many assembly-language
pseudo-ops that have appeared that we've never seen any
references to before ... but it applies to the regular
code as well.
- Added a link to Ken Shirriff's delightfully absurd
blog article "Bitcoin
mining on an Apollo Guidance Computer: 10.3 seconds
per hash" to the
AGC-restoration page. He does his mining on
the restored physical AGC, but shows you how to do it
with Virtual AGC too.
- And another great treat, our
first actual IBM LVDC source code, from a 1967
version of the LVDC flight program! It's just a
few pages of trig and square root routines, but you can
see from the snapshots that there's a full (or at least
very substantial) program listing beyond just those few
samples. It probably does not conform 100% to the
syntax of the assembler I wrote for it a decade ago, but
obviously at some point I'll fix up the assembler.
Unfortunately, my anonymous informant does not
indicate that we will be receiving the full listing, and
indeed implies very strongly that we will not. So
I can't you promise anything further. Which is
disappointing. But the very positive takeaway is
that assembly listings of the LVDC flight program do
still exist ... a possibility which previous informants
have poo-pooed up to now.
- I've removed some anecdotal bits of info from the LVDC page, relating to who wrote the software and how it was written, because I no longer have confidence in those anecdotes. None of the technical info has changed.
- Added the CAD transcription for drawing 2010062F
(Block II CDU power supply).
If you've never given the CDU any thought — and I know I hadn't! — it's interesting and eerie the way it shadows the AGC design. In particular, it consist of "modules", plugged into a backplane, with each module being either a regular analog circuit or else a "logic-flow" circuit consisting entirely of NOR gates. I suppose it's reasonable that once they had a design paradigm they'd probably stick with it, but it's still fun to see. The CDU itself converts data from whatever forms it's available in the spacecraft to whatever digital format the AGC needs, and vice-versa, so you can think of it crudely as a set of A/D and D/A converters ... but from an era where such things didn't just come off-the-shelf but had to be designed and implemented anew with each project.
But it's also based on a circuit-design practice that we associate only with Block I and early Block II. For example, the schematic shows no pin numbers for the NOR gates, nor distinguishes between the "A" and "B" gates of the dual-NOR-gate chips. For that information you have to look at an entirely separate drawing, the so-called "signal wiring" diagram. That design practice fortunately fell out of favor quickly in the AGC schematics (thank heaven!), but unfortunately persisted to the very end in the CDU schematics ... or at least in the CDU READ COUNTER MODULE. As a result, I can't claim total confidence of the NOR-gate pin numbers used in the CAD transcription, due to the difficulty of proofreading them; on the up side, though, probably nobody will ever notice if I didn't get some of them quite right!
- Somehow, one of the files needed for Retread50 hadn't
gotten into the repository, and this killed the entire
build as soon as it got to that point in the
process. Weird, since our GitHub repository is set
up to do a trial build whenever a commit to it is
performed (which it did, and naturally, failed), and to
email me about failures (which it didn't, as far as I
can tell). At any rate, I've added the missing
file now.
- Also, building Virtual AGC on newer Macs with clang
(which, having only old Macs, I've never had any means
to try) weren't working. But a
couple of extra instructions have now been added
that may do the trick. Is it a complete fix?
Time will tell.
- We have been given a version of the AGC software that we didn't previously have! The program is RETREAD 50, and you may recall that we already had gotten the similar program RETREAD 44 from Don Eyles. However, we've gotten RETREAD 50 in a way completely different from all other AGC software. We have not been given an assembly listing for RETREAD 50. Rather, the AGC-restoration project (which you may have gotten wind of) was allowed to borrow core-rope modules containing RETREAD 50 from the Computer History Museum, thus allowing them to obtain a dump of the ropes, and (for good measure) regenerating the source code for it. And we're the beneficiaries! See our LUMINARY page and/or our GitHub software repository.
- In order to properly described how and why we managed
to get RETREAD 50, I found myself writing an entire page devoted to just
a description of the AGC restoration effort.
You'll see that a link to it now appears at the bottom
right of the banner across the top of all our
pages. It's not quite complete yet, but feel free
to check it out!
- Finally have the G&N assembly drilldown fully up-to-snuff ... just in time to go get more scans next week and to fall behind with it again.
- Added various more Grumman LM drawings to the miscellaneous
drawing index page.
Corrected my misspelling of Tim Good's name. (D'oh! It's a short name, so it seems like it would have been easy enough to get right the first time.)
- In doing some semi-automated checking of the G&N assembly drilldowns, I've discovered to my horror that a lot of drawings that you'd never suspect were assemblies actually are assemblies. Maybe 90% of them! I mean, really, who would suspect that something called a "cover" or a "plate" is really an assembly? I ask you. I never even bothered to look at them. The upshot of that is that the assembly drilldowns I've made are actually nowhere near as complete as I imagined, since I didn't have any support for drilling down a bunch of those non-assembly assemblies (with apologies to Woodward & Bernstein). So I've made a tentative new beginning with some updates to the drilldowns, but there's a long way to go.
- But there's a bit of a treat today as well: We've gotten a few
top-level LM engineering drawings from the
aperture-card boxes at NARA-SW, and perhaps someday
we'll be able to explore the LM engineering drawings in
much the same way we're now exploring the G&N
engineering drawings. Check them out! One
drawback with them is that while each drawing calls out
the drawings for its sub-assemblies, it does so only by
drawing number and no drawing name. Furthermore,
the drawings themselves have only numbers in their title
blocks, and have no actual titles. So I can't
personally tell you what most of the assemblies
are. Anyone who wants to offer up a solution to
this conundrum, please do so, since it will make
figuring out these assemblies quite difficult!
The new representation appears to have a lot more missing drawings in it than the old one does, but that's a bit misleading. Many of the missing drawings are SCDs or drawings for G&N components we just haven't been collecting until recently, and therefore the gaps will hopefully fill in significantly as the effort of scanning the engineering-drawing microfilm at NARA SW proceeds. Naturally, they'll never fill in completely.
- A variety of drawings for mil-spec parts used by the AGC/DSKY/G&N mechanical drawings have been posted online, and can be accessed through a new mil-spec parts index page, or by means of the engineering-drawing search engine.
- Document MIL-D-70327,
called out by almost all AGC/DSKY/G&N electrical
schematics, has been added to the reference
section of the electro-mechanical page.
A side effect of these problems was that on the yaDSKY page of the website, the mission-by-mission arrangements of the DSKY indicator lamps and their colors that I posted yesterday also had errors, because they were based on the wrong DSKY part numbers. That has been fixed, with the result (not too surprisingly) that the Apollo 12 LM did have the same indicator lamp arrangement as the other missions, rather than a different one as I claimed yesterday, and Apollo 5 did as well.
This issue with Apollo 5 is actually slightly interesting, in that it turns out there were engineering drawings both for the configurations MIT delivered to NASA and separate engineering drawings for those NASA actually installed in the spacecraft. These two configurations usually call out different AGC and DSKY part numbers. That distinction, along with some other subtleties, escaped me when creating the drilldown table. For example, MIT delivered DSKY 2003985-051 for Apollo 5 (or rather for G&N system 603 for LM-1), which has a rather funky indicator-lamp arrangement; but NASA ended up installing DSKY 2003985-081, which has a "normal" arrangement. Who knew? Well, obviously, a lot of people other than me! There are changes like that across the board, though only this one involved a change in the DSKY's lamps. Just one more reason to be careful, I suppose.
- The approaching 50th anniversary of Apollo 11 has sparked interest from various writers, and in reviewing some of our online materials so as not to make a complete fool of myself when talking to them, I can't help but notice various stuff that is out of date on the website. Hopefully I've been able to make a dent in those, though I'm sure I haven't caught everything.
- Speaking of which, I had apparently forgotten to make any comments here about the new article by Brian Hayes in American Scientist magazine, "Moonshot Computing". In particular, Virtual AGC gets a short section of it's own. But size, I've heard, isn't everything ... so check it out. It's a terrific article!
- On the yaDSKY page, the mission-by-mission arrangements of the indicator lamps and their colors were previously speculative. But by navigating through our recently-created engineering-drawing tree, I was able to fill them in for every mission. It turns out there had been errors in the DSKY indicator lamps for Apollo 12 and 17, and that I had never gotten around to specifying the colors at all. I haven't actually made any changes to the software related to this fix, but I'll get around to it at some point. Probably.
These boxes mostly continue with electrical and
mechanical drawings of CM/LM guidance-system components
like the CDU (coupling data unit), PIPA (pulsed
integrating pendulum accelerometer), SXT (sextant), SCT
(scanning telescope), and so on.
I also eliminated some information that was redundant
across all of the box-index pages, because that info
(however well-intentioned) was making it quite difficult
to add new index pages.
- Added the CAD transcription for drawing 2005973- (indicator driver module D1-D6 for Block II DSKY 2003994). See also the renderings of the CAD as image files. But wait, you say, didn't you just add a different drawing (2005940A) yesterday and say exactly the same thing about it?!!! Why yes, I did, thank you for noticing. DSKY 2003994 is one of only a handful of cases I've encountered in which there's an inconsistency in its drawing tree as to which schematic is applicable. The indicator driver module assembly (2003952-031) for DSKY 2003994 calls out schematic drawing 2005940, whereas the relay circuit assembly (2003910-021) of that selfsame indicator driver module assembly calls out schematic drawing 2005973 instead. The two schematics are almost, but not quite, identical. Unfortunately there's no way to know for certain which is which with the information we have at present. Often in this case, we'd resort to looking at AC Electronics document ND-1021042, but it is also inconsistent, calling out schematic 2005973 in some places, but showing circuitry from 2005940 in others. Nevertheless, there are quite a few circumstantial reasons to believe that 2005973 is the correct one ... not least of which that its signatures are dated later. You can read all of my reasoning on that, in my usual boring detail, on any of the DSKY 2003994 drawing-tree pages.
- Back when I originally did the engineering-drawing drill-downs for the various AGC and DSKY models that are listed on the electro-mechanical page, there were a number of drill-downs I couldn't complete, due to missing drawings. Well, there are still missing drawings, but in the meantime we've acquired lots and lot more scans than before, so it should be possible to fill in some of those gaps. While it's still early in the process of filling in the gaps, here are some of the assemblies whose drill-downs have been addressed so far:
- AGC model 2003993-0xx oscillator
module, B7.
- AGC model 2003993-0xx erasable
driver module, B9-B10.
- AGC model 2003993-0xx rope driver module B16-B17.
- DSKY model 2003950-011 keyboard module D8.
- DSKY model 2003985-051 keyboard
module D8.
- DSKY model 2003950-061.
- All Block II AGC models, miscellaneous drawings.
- Added MIT/IL
document E-1186 to the document library.
Chapter 4 will tell you everything you want to know, I
would suppose, about TDRR's, and will help to explain
the TDDR numbers that pepper the revision blocks in the
Apollo engineering drawings.
- Added the CAD transcription for drawing 2005971 (power-supply module A30-A31 for Block II AGC 2003993). See also the renderings of the CAD as image files. Unlike my normal practice, I took some liberties with this one, in that the latest revision of the original drawing 2005971 we have is "A", but it is missing its 2nd sheet (the bill of materials). I therefore transcribed sheet 1 from the original 2005971A, but I transcribed sheet 2 from the original 2005971-, thus producing a hybrid revision that I call "2005971-A". I've compared the resistor, capacitor, and inductor values between the two sheets to insure there are no obvious revision mismatches between the two sheets, but there's no way to detect incorrect part numbers for things like diodes and transistors. Not that it matters too much, since you probably can't get those diodes or transistors any longer, but I still don't like it.
- Added the CAD transcription for drawing 2005940A (indicator driver module D1-D6 for Block II DSKY 2003994). See also the renderings of the CAD as image files.
- Added the CAD transcription for drawing 2005928A (interface module A25-A26 for Block II AGC 2003993 and an alternative to drawing 2005021C for some AGC 2003200 dash numbers). See also the renderings of the CAD as image files.
- Added the CAD transcription for drawing 2005929A (sense amplifier module for erasable memory, B14, for Block II AGC 2003993). See also the renderings of the CAD as image files.
- More fixes to the master engineering-drawing index and
search engine.
- Added the CAD transcription for drawing 2005932A (erasable-memory sense-amplifier module B13 for Block II AGC 2003993 and an alternative to drawing 2005920B for some AGC 2003200 dash numbers). See also the renderings of the CAD as image files.
- Added the CAD transcription for drawing 2005926A (strand-select module B15 for Block II AGC 2003993 and and an alternative to drawing 2005924- for some AGC 2003200 dash numbers). See also the renderings of the CAD as image files.
- Added the CAD transcription for drawing 2005927A (alarm module B8 for some Block II AGC 2003993 and 2003200 dash numbers). See also the renderings of the CAD as image files. I also found and fixed a number of boo-boos related to module B8 in the existing html files and drawing search-engine.
- Added the CAD
transcription for drawing 2005925A (current-switch
module B11 for Block II AGC 2003993 and and an
alternative to drawing 2005005D for some AGC 2003200
dash numbers). See also the
renderings of the CAD as image files.
- Hartmuth Gutsche tells me that the
Apollo online digital archive of the University of
Alabama at Huntsville, having apparently been
offline for a couple of years, has returned from
whatever limbo it may have been in. It contains
around a thousand documents. I've leafed through
all of them and pulled down 40 or so for our own digital library page
just in case the UAH site decides to disappear
again. You can find them in our library by looking
for the icon. As you might imagine, though,
given that almost all of this stuff came from Marshall
Space Flight Center, most of the UAH documents relate to
the big rocket, and mostly have little direct relevance
to what's going on here at Virtual AGC. Most of
the ones I pulled relate to Saturn IV-B stage
(containing the Instrumentation Unit, containing the
Launch Vehicle Digital Computer), or to the Apollo
Telescope Mount (Skylab), or to press materials for
Apollo 4 through 7. thanks, Hartmuth!
- Thymo van Beers sent me a list of various boo-boos in my own AGC developer documentation that need to be fixed, and after lazily sitting on that list for a while — a couple of months, it looks like — I've finally gotten around to incorporating his suggestions. Thanks, Thymo!
- Updated the discussion of aperture cards in the FAQ.
- Added engineering-drawing index pages for
aperture-card boxes 458 and 462, and updated the page
for box 461 to include the previously-unscanned final
half of the box. The changes are completely
preliminary, and probably error-ridden, since although I
have all of the scanned drawings in hand, I haven't
posted them online yet. So the new/updated box
indexes aren't actually of any use yet.
- Somewhat pepped up the engineering-drawing search page I added yesterday, so that the search results have much more intuitively obvious search titles and URLs. Of course, as always on this site, I make no pretense that "more intuitively obvious" is the same as merely "intuitively obvious", and in fact as I recall being taught in school, I should probably be saying something like "less intuitively unobvious". But you get the idea.
- Added the CAD transcription for drawing 2005268- (Block II AGC 2003200 module A18 electrical schematics). See also the renderings of the CAD as image files.
"Fixed" is in quotes earlier, because I imagine few other
people would be bothered by such trivial stuff, and probably
just think it was unnecessary grinding on my part. On
the plus side, though, KiCad's ERC capability (once it was
working again) had advanced somewhat since I had originally
run it on these schematics, so it also found a handful of
actual electrical problems for me that I was able to
fix. Thus the exercise wasn't entirely
pointless. For anyone unlucky enough to have hardcoded
some links or shortcuts to the PNG files in
our rendered CAD folder, I'm pretty sure that I ended
up changing the names of a few of those files, so you might
want to check your links. My apologies for that.- Added the CAD transcription for drawing 2005265- (Block II AGC 2003200 module A15 electrical schematics). See also the renderings of the CAD as image files. Revisions "-" and "A" (for AGC 2003993) differ only in the backplane signal for connector pin 317.
- Added the CAD
transcription for drawing 2005267- (Block II AGC
2003200 module A17 electrical schematics). See
also the renderings of the CAD
as image files. Revisions "-" and "A" (for
AGC 2003993) differ only in the backplane signal for the
inputs and outputs of gate 44462 are no-connects on the
former but not the latter.
- Added the CAD transcription for drawing 2005257- (Block II AGC 2003200 module A10 electrical schematics). See also the renderings of the CAD as image files. There's no electrical difference from 2005257A (for AGC 2003993).
- Added the CAD transcription for drawing 2005258- (Block II AGC 2003200 module A11 electrical schematics). See also the renderings of the CAD as image files. There's no electrical difference from 2005258A (for AGC 2003993).
- Added the CAD transcription for drawing 2005253- (Block II AGC 2003200 module A12 electrical schematics). See also the renderings of the CAD as image files. Differs from 2005253A (for AGC 2003993) only in the backplane signal used for connector pin 249.
- Added the CAD
transcription for drawing 2005264- (Block II AGC
2003200 module A14 electrical schematics). See
also the renderings of the CAD
as image files. There's no electrical
difference from 2005264A (for Verilog simulation) or
2005264B (for AGC 2003993).
- Added the CAD transcription for drawing 2005252- (Block II AGC 2003200 module A7 electrical schematics). See also the renderings of the CAD as image files. There's no electrical difference from 2005252A (for AGC 2003993).
- Added the CAD
transcription for drawing 2005256- (Block II AGC
2003200 module A9 electrical schematics). See also
the renderings of the CAD as
image files. The difference between this rev
"-" and rev "A" (for AGC 2003993) is that in the latter,
several previously-disconnected gates are connected to
backplane signals, with the net result that the
backplane STRT2 signal is wire-NOR'd with the backplane
signals CLROPE, ROPER, ROPES, and ROPET. However,
this is a change only on the backplane wiring and not
within the module itself, so it is not an electrical
change within the module.
- Added the CAD transcription for drawing 2005263- (Block II AGC 2003200 timer module A6 electrical schematics). See also the renderings of the CAD as image files.
- Our
GitHub repository now has a "mechanical" branch,
into which I semi-confidently expect 3D models of AGC,
DSKY, and perhaps other G&N system component
fabricated parts (such as baseboards, faceplates,
covers, and so on) to be placed ... hopefully starting
in the relatively near future. But it's just empty
right now except for a README that covers my hopes and
expectations in more detail. There's also a place
there for storing 2D CAD transcriptions of scans of the
original Project Apollo mechanical drawings, but people
have expressed so little interest in that (compared to
interest in 3D models) that we'll probably be able to
count them on the fingers of one toe.
- Added yet another clever trick (to supplement those added yesterday to the Box 459, Box 460, Box 461, and miscellaneous G&N engineering-drawing pages) for fooling our Internet Archive site into letting you download full-resolution imagery.
- Because of teething difficulties at the beginning of
this process of scanning entire boxes of aperture cards,
there are several instances in type 02 documents in
which page 18 was misinterpreted as page 1, and thus the
page 18 scan overwrote the page 1 scan; similarly, in
which page 28 overwrote page 2 and page 38 overwrote
page 3. This has been fixed in the Box 459, Box
460, and Box 461 indices. I hope. There are
also related cases in which multiple microfilms of the
same drawing appear in the aperture-card boxes, but only
once in our collection due to overwriting of files of
the same name; this will be eliminated in future boxes
(i.e., we'll have access to all of the scans, duplicate
or not), but it doesn't seem worth it to try and fix the
problem in boxes that have already been scanned.
- Fixed up the (currently partial) index for aperture-card Box 461 the full titles of the drawings.
- As some sort of asinine tribute to the sickening power of cut-and-paste for evil, I had apparently titled drawings 2005251 through 2005273 in Box 460 as "signal wiring diagrams", when they are really "logic flow diagrams". That's fixed.
- On the various engineering-drawing index pages, which
usually provide links to our Internet Archive site for
the individual drawing scans, there are warnings that
using the Internet Archive's "save image as" function
will usually give you an inferior image quality.
However, I've found much better workarounds for that
problem than when I originally wrote the warning, so
I've modified those pages to give better advice about
the workarounds.
- Added the CAD transcription for drawing 2005262- (Block II AGC 2003200 stage branch decoding module A4 electrical schematics). See also the renderings of the CAD as image files.
- Added the CAD transcription for drawing 2005261- (Block II AGC 2003200 cross point generator no. I module A5 electrical schematics). See also the renderings of the CAD as image files.
- I've removed the "experimental page" warning at the top of the pages for Box 459 and Box 460 MIT/IL engineering drawings, since as far as I can tell (without literally checking all 3600 index entries) the indices are fine. It's definitely worth noting, though, that the indices were generated from the punches on the aperture cards holding the microfilms of the drawings, and that not only is the metadata punched there not 100% perfect or consistent, but more importantly, the scanner manufacturer's software that reads the punches during the scan is subject to all kinds of problems ... specifically, systematic substitution of some characters for other characters. Thus my index-generation software has to undo a lot of errors introduced by the scanning software, and that's impossible to do 100% perfectly. So I just hope it's good enough! So far, I think it is. Ask me again if I think so 10 boxes or 100 boxes from now.
- I've added a page for the scans from Box 461,
although the box is presently incomplete due to issues
with the scanner, which I hope will be resolved fairly
quickly, but am unsure enough of that to post the
partial contents that have already been scanned ...
about half the box. Or to put it more bluntly, the
scanner is broken and needs to be repaired. Box
461 gets into a lot of G&N components we've ignored
previously (IMU, SCT, PIPA, CDU) but it's only a taste
of what's to come.
- Added the CAD transcription for drawing 2005260- (Block II AGC 2003200 timer module A2 electrical schematics). See also the renderings of the CAD as image files.
- Added the CAD transcription for drawing 2005251- (Block II AGC 2003200 SQ register and decoding module A3 electrical schematics). See also the renderings of the CAD as image files.
The first two of these
complete boxes, #459 and #460, have now become
available. In order to keep our web-pages containing
the drawing indexes from spiraling too far out of
control, this has necessitated a change to the structure of
the drawing indexes. Instead of a single, huge
drawing-index page such as we had previously (which had
about 5000 entries before complete boxes started becoming
available), there will now be a series of such index pages,
each relatively limited in scope:- ...
- Index page for
box #459 (~1800 drawings)
- Index page for
box #460 (~1800 drawings)
- ...
- Miscellaneous index page (~5000 drawings)
Since each aperture-card box corresponds to a specific,
known drawing-number range, hopefully this will still be a
relatively easy system to navigate.
I know that most people would handle this by setting up a
database, so as to be able to find everything by browsing
or searching the database rather than having hard-coded
HTML tables of link data, but I'm philosophically
committed to having a standalone website that doesn't need
any software on the backend server, and hence could be
(for example) downloaded to anybody's local system.
Unfortunately, since (due to storage requirements) almost
all of the engineering-drawing scans have been put onto
our Internet Archive site rather than this main Virtual
AGC site anyway, that principle is already
invalidated. But still, my philosophy, website-wise,
is "the dumber the better" in terms of its software
requirements. And I'm sure that's obvious to anyone
looking at this site who's au fait on such stuff.
- Added the CAD transcription for drawing 2005009A (Block II AGC 2003100 strand-select module B15 electrical schematics). See also the renderings of the CAD as image files. This is a closely related drawing to 2005924- (for Block II AGC 2003200), so I corrected various bugs in the existing 2005924- transcription at the same time.
- Added the CAD transcription for drawing 2005006- (Block II AGC 2003100 erasable memory module electrical schematics). See also the renderings of the CAD as image files. This is a closely related drawing to 2005106- (for Block II AGC 2003200), so I corrected various bugs in the existing 2005106- transcription at the same time.
Incidentally, unless I'm confused somehow, I think these
are the last CAD transcriptions of electrical schematics
for the early Block II AGC model 2003100.
- Added the CAD transcription for drawing 2005914- (Block II AGC 2003100 erasable-memory sense-amplifier modules B13-B14 electrical schematics). See also the renderings of the CAD as image files. This is a closely related drawing to 2005920B (for Block II AGC 2003200), so I corrected various bugs in the existing 2005920B transcription at the same time.
- Added the CAD
transcription for drawing 2005010F (Block II AGC
2003100 power-supply modules A30-A31 electrical
schematics). See also the
renderings of the CAD as image files. This
is a closely related drawing to 2005916A (for Block II
AGC 2003200), so I made some corrections to 2005916A at
the same time. I also noted that several of the
web-pages for Block II AGC model 2003993 mistakenly
called out drawing 2005010 due to ambiguities in the
original drawings, and so fixed those pages to call out
what I think is the correct drawing (2005971) instead.
CAD transcriptions of the electrical schematics for the
Block I DSKY relay modules D7-D14 have been added:
- Early model NAV & MAIN DSKY: CAD for drawing 1006161C (plus rendering as image file)
- Late model NAV & MAIN DSKY: CAD for drawing 1005780- (plus rendering as image file)
This actually completes the CAD transcription of all Block I DSKY schematics, and given that CAD transcription of the Block I AGC schematics had already been completed a couple of weeks ago, that means that I've now finished all of the Block I electrical CAD. Of course, you have to take that "all" with a grain of salt, since there's at least one known missing original drawing (later-model NAV DSKY keypad) which I obviously have not transcribed, and I haven't bothered with creating a schematic for the wiring that interconnects all of the DSKY modules. But I'm pronouncing it "done" anway.
The next goal is filling in all of the gaps in the Block II electrical CAD transcriptions. I had completed Block II AGC model "2003200" (without any specific dash number) about 4 months ago, but the state of our knowledge of the specific engineering-drawing trees for the different AGC/DSKY models was primitive back then ... indeed, practically non-existent. So the task now is to get CAD transcriptions for the drawings for all of the specific Block II AGC & DSKY models we're supporting.
The electrical schematics for drawing 2005028A (Block II AGC alarm module B8) have been transcribed to CAD. See also: the renderings of the CAD as image files. This is for AGC p/n 2003100-021 only, since all other model/dash-numbers for which we have the corresponding drawings use other alarm-module circuits from drawings 2005922 or 2005927 instead.
CAD transcriptions of the electrical schematics for the
Block I DSKY power-supply module have been added:
- Early model NAV & MAIN DSKY: CAD for drawing 1006163G (plus rendering as image file)
- Late model NAV & MAIN DSKY: CAD for drawing 1005756- (plus rendering as image file)
Because the availability of the original drawings for the
Block I DSKYs isn't 100% complete at present, I can't
state with 100% certainty that these CAD transcriptions
cover all models. But as far as I can tell
with from the available drawings, they do.
- The electrical schematics for Block I NAV DSKY (early models 1003458 & 1003524 only) drawing 1006160E, keyboard module D17, have been transcribed to CAD. See also: the renderings of the CAD as image files.
- The electrical schematics for Block I MAIN DSKY (early models 1003459 & 1003540) drawing 1006150D, keyboard module D18, have been transcribed to CAD. See also: the renderings of the CAD as image files.
- The electrical schematics for Block I AGC drawing 1006119D, rope sense amplifier module B26 & B27, have been transcribed to CAD. See also: the renderings of the CAD as image files.
- The electrical schematics for Block I AGC drawing 1005700A, filter module B5, have been transcribed to CAD. See also: the renderings of the CAD as image files. This power-supply module appeared in later Block I AGC models, but seemingly not in the early models.
Unless I've slipped up somewhere, which is entirely
possible, this completes the CAD transcriptions for all
electrical schematics for all supported Block I AGC
models. (Not DSKYs ... I haven't started on those
yet.) Since it's easy to read this statement as
meaning that all Block I AGC schematics have been
converted to CAD, which isn't true, let me parse it out a
little more fully. We "support" only the 8 different Block
I AGC models listed on the
electro-mechanical page. For two of those
models (1003469-011 & 1003700-011) we don't even have
the specific original electrical schematics for module A23
(namely drawing 1006125), while for two other models
(1003700-051 & -071) we don't have the electrical
schematics for module A29 (drawing 1005763), so naturally
there are no CAD transcriptions for those particular
modules in those particular AGC models.
Nevertheless, that's a lot of drawings transcribed to CAD,
and remarkably good coverage of the Block I AGC electrical
design! I'm sure there are still plenty of boo-boos,
such as slightly inconsistent signal names from one module
to the next, that will need to be worked out over time.
- Added (to NARA finding aids on the Quest for Info page) a document that purports to list all documents processed by the JSC technical library up to 1988.
- Added a handful of new
AGC/DSKY engineering-drawing scans which Mike
Stewart and Craig Keithley contributed. Alas,
there's really no good way to point out which ones these
are, so I'd just suggest doing a numerical or textual
search to see if anything you're looking for is there.
This turned out to be a bit trickier than usual because of a conundrum I ran into in the process, namely that the connector pins in the schematic are numbered in an impossible way. Literally. And having no idea what that meant, it brought me to a screeching halt, mid-transcription. I was tempted to just call it all a mistake on the original engineer's part, and renumber the connector pins as I liked in the transcribed CAD. But that strategy was a bit tricky to rationalize, since the original drawing was at revision "F" and thus had already been through multiple revisions without this problem (if it was one!) having been detected and corrected. Not only that, but the partial schematics that had been redrawn in AC Electronics document ND-1021041 agreed with the impossible numbering in the schematic, to the extent that ND-1021041 deigned to provide those kind of details. So what was happening? It was maddening! Had the spacetime continuum become not merely warped, but completely bent? Was it a sign at last that those fakers back in the 60's had slipped up, and I finally had the evidence in hand to out the whole fraudulent "moon landing" hoax as a public disgrace? Had I, indeed, finally slipped into madness or senility and needed to be carted away to an institution of some appropriate flavor where I would only be fed soft foods in perpetuity and given pills in little paper cups to be swallowed under the watchful eyes of white-coated people?
Fortunately, no. I asked for help in resolving the problem, and as it often turns out in these situations, Mike Stewart (thanks, Mike!) happened to know something that I didn't know, namely that this circuit module, of which two are used in the Block I AGC, is plugged in backwards in slot B11, even though it is plugged in forwards in slot B10. Thus the pin numbering for module B11 is the opposite of that for module B10, even though the two are physically identical. This entirely resolves the paradox.
And that, children, is how my sanity, the integrity of the Project Apollo, and indeed the entire structure of spacetime, were saved on this day, the Nones of March, in the year of our Lord (or not, if you disagree) 2019!
- The electrical schematics for Block I AGC drawing 1006097F, power-switch module B2, have been transcribed to CAD. See also: the renderings of the CAD as image files.
- All of the CAD drawings so far transcribed for the
Block I and Block II AGC that have depended on reusable
circuit blocks have been "reannotated". The
modules in question are basically all of the analog "B"
modules (as opposed to the digital "A" modules).
What this nonsense statement means is that the reference
designators have been corrected to hopefully agree with
those physically marked on the original modules, as
opposed to using many reference designators arbitrarily
assigned by the KiCad program. If that still
sounds completely opaque ... well, it's something that's
only really meaningful to someone working with actual
AGC B-modules, and not useful to someone who simply
wants to casually look through the schematics (which I
expect is 99% of anybody interested in these CAD
transcriptions of the original schematics at all), so I
won't clutter up this space with further
explanation. Suffice it to say that it's a fix for
an inconsistency with respect to the original design
that has been bugging me for months and months,
so I'm glad that it has finally been taken care of.
- 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 module A35, namely drawing 1006541B, have been transcribed to CAD. See also: the renderings of the CAD as image files.
- The electrical schematics for Block I AGC module A36, namely drawing 1006557D, have been transcribed to CAD. See also: the renderings of the CAD as image files.
- Don Eyles has pointed out that I have been a bit too aggressive in my acknowledgements of the original AGC developers, to the point where I was acknowledging some folks that weren't even AGC software developers at all. (Specifically, people who worked on the "all-digital simulation", which was an important task and a great contribution, but not AGC software development.) So I've removed some names that used to be in the acknowledgements. If you're one of the people affected, my apologies! If I had some way to cover the all-digital simulation (and you) here on this site, I would, but my information about it and my resources are not unlimited. Particularly the former.
- The electrical schematics for Block I AGC module A32, namely drawing 1006546A, have been transcribed to CAD. See also: the renderings of the CAD as image files.
- 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.
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!
- The electrical schematics for Block I AGC module A17, namely drawing 1006543D, 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. While the two implementations differ slightly, I believe that that's just due to errors in ND-1021041, but you can read the writeup about the discrepancies here if you like.
- It turns out that the master MIT/IL engineering-drawing index page had immensely more garbage in it than I imagined yesterday. It's still big, but it's now a fraction of the size it was yesterday, as well as eliminating loading of an external stylesheet I hadn't known about, so it hopefully will be a tad more responsive than before. Plus, its table borders had disappeared when viewed in Chrome for some reason, and I've brought them back.
- The electrical schematics for Block I AGC module A17, namely drawing 1006543D, 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 differ, primarily in that there are 7 NOR-gates which are wired up differently, resulting in 7 changes of polarity in the backplane signals. Therefore, I think there is probably a later revision of the schematic that we don't have. You can read the full writeup of the discrepancies here if you like.
- The electrical schematics for Block I AGC module A26, namely drawing 1006549B, 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 are electrically identical.
- Because of the WYSIWYG HTML editor I normally use on
this website, the HTML becomes littered with junk like
big blocks of useless crud and thus has to be cleaned up
from time to time to keep this junk from proliferating
too much. Which I've just done. The
improvements in some file-sizes (particularly this
change log page and the MIT/IL drawing-index page) are
semi-dramatic. Unfortunately, the automated
cleaner did mess up a couple of my tables ... all of
which I hopefully found and fixed, though I guess it may
take a while to be sure.
- The electrical schematics for Block I AGC module A28, namely drawing 1006552A, 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. My assessment is that the two versions are essentially the same, though that is open to interpretation. There's a full analysis of the differences as well.
- The way hyperlinks into our Internet Archive site on the electro-mechanical page have been treated has increasingly bugged me, so I've changed the treatment to correspond to how the engineering drawing index page and the individual pages for AGC/DSKY models treat them. Alas, it turned out to be really complex, because of some inconsistencies in the way those hyperlinks are supposed to be formatted. I think I've got them all right, but it's possible there might be some broken links on the electro-mechanical page that it will be discovered and fixed over the course of time.
- Information
has
been added to the CAD-file section of the
electro-mechanical page about the expectations for 2D
or 3D transcription of AGC/DSKY mechanical drawings
into CAD form.
- The electrical schematics for Block I AGC module A21, namely drawing 1006556A, 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 remaining differences after this reconciliation process lead me to believe that ND-1021041 may have been based on 1006556C ... i.e., a couple of revisions higher than our latest revision of the schematic drawing. The match is quite close, though, with just 3 gates (and associated connector pins) differing. There's a full analysis of the differences as well.
- It also turns out, now that I've worked through a 2nd
drawing, that the Block I signal-wiring diagrams are
don't unambiguously provide the wiring of the logic from
the schematic in all cases, so I've added the necessary
verbiage about that issue to the
explanation
of Block I signal-wiring diagrams on the
electro-mechanical page.
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.
