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2021-08-03
Unlike the AGC software, our documentation for the AGS (LM's abort computer system) is relatively meager, to the point where it's tough even to be certain which of the known versions of the software were used for which of the Apollo missions.  In other words, we haven't yet uncovered any convenient table in the contemporary documentation that just lists all of the installed AGS software versions.  Recall that there are 8 known versions of this abort-system "flight software", of which we have copies of only 2 (namely, Flight Program 6 and 8).  Well, Cooper Lushbaugh (thanks, Cooper!) has taken it upon himself to dig more deeply into the various abort-system documents than I had done, and to come up with some of those missing answers.  The bad news is that Apollo 14 turns out to have used Flight Program 7, of which we don't have a copy.  And Apollo 13 may have used Flight Program 7 too.  (But it's still possible that Apollo 13 may have used Flight Program 6; even Cooper's extra digging hasn't told us for sure.)  As far as Apollo 11-12 and 15-17 are concerned, though, we seem to remain on solid ground that they used Flight Programs 6 and 8, respectively.
2021-06-06
  • On the document-library page, I reset the  indicators — last reset nearly two years ago, so no wonder they had become pretty useless!  They'll only adorn newly-added documents from today forward.
  • Added the North American Aviation document "Apollo Electrical Installation" to the document library, thanks to Mike Stewart.  The document happens to contain a partial explanation for NAA's CSM drawing-number scheme, which we didn't previously have, so our electro-mechanical page was also updated with some of that information.
  • Added several documents related to the Apollo 11 flight readiness review to the document library.
  • Added a memo titled "June 5th Apollo Spacecraft Software Configuration Control Board (ASSCCB) meeting" to the document library.  Yes, sounds pretty dry, I know, but it contains the full texts for PCR 780 and PCR 815, relevant (particularly the latter) to the somewhat-ongoing effort to reconstruct Comanche 67 (Apollo 11 CM) software from Comanche 55 (Apollo 11) et al.
2021-05-30
  • I made some additional clarifications for the build instructions for yaAGC's WebAssembly target on the download page.
  • Andy Smith has just completed his rather major effort to find and correct symbol misspellings in the AGC code base, as well as correcting various other bits of formatting discrepancies (vs the original listings) he found along the way.  These changes are now present in the AGC source-code files in our GitHub software repository, as well as in the colorized, syntax-highlighted code listings on this site.  In case you wonder what I mean when I say "major", there are presently 2575 AGC source-code files, of which Andy's effort affected 2456 of them.  That's not to say that the files were completely riddled by errors, but that a single misspelling can infect a large number of source files.  For example, the symbol ENDDCM, misspelled as ENDOCM, infected 26 files.  (Naturally, none of these typos resulted in any errors in the core ropes, which were and remain good.)  If you're curious, the complete set of file diffs can be viewed at this link.  Great job, Andy!  The only code not affected by Andy's audit is the Comanche 67 reconstruction I've been intermittently working on, and of course that's not because it doesn't have misspellings — which I'll have to take care of later — but because I've never merged it into the main branch of the repository.

As you may infer from earlier entries in this change log, Andy employed a smart method for this audit, rather than relying on the brute-force approach of simply eyeballing all of the original source listings.  His method instead involved comparing the symbol tables found at the end of each of the original listings against the symbol tables output by a modern assembly of the source files.  He used an AGC assembler he had created himself, which listed the symbols in the same order as the original assembler did, and formatted the printouts the same way as the original assembler did, thus making a comparisons easy. 

Which is not to say that he compared every entry of every symbol table.  No, he merely compared the first row of each column on each page of the symbol table, which is adequate to catch the vast majority of problems.  But not all!  So it's still possible that a much smaller number of misspellings continue to lurk, undetected.  Admittedly, I kind of doubt it.  If anyone wants to volunteering for the mind-bending task of checking the symbol tables more closely, I'm sure it would be appreciated.

When Andy started this audit, Virtual AGC's assembler (yaYUL) neither sorted the AGC symbols in precisely the same collating sequence as the original assemblers (YUL, GAP) and Andy's assembler, nor formatted/paginated the symbol tables similarly.  Andy has woken me up to the value of this, and as you may recall from a change-log entry a month or two ago, yaYUL now sorts, formats, and paginates symbol tables in a way that facilitates such comparisons.  That's one of the changes incorporated as of today in the colorized, syntax-highlighted AGC listings on this site.

2021-05-28
On the download page:
2021-05-27
Updated the description of the WebAssembly target on the download page to cover the exact steps (at least on Linux Mint 19) for loading the ported yaAGC into the demo web page, and running the demo web page on the local computer.
2021-05-26
On the download page (and the GitHub code repository), there's now a WebAssembly target for building Virtual AGC from source.  The WebAssembly target is a way of running the AGC CPU emulator (yaAGC) natively within a web-browser.  Many thanks to Michael Franzl for working out how to do this, as well as providing demo HTML/JavaScript for actually running the simulation in a browser.  This target is not built by default when you build Virtual AGC, since it relies on some one-time setups most people wouldn't normally have in place on their computer systems, but nevertheless can be manually built in a simple, straightforward fashion.

You may recall that Shahriar Iravanian had earlier provided a pure-JavaScript port which serves a similar purpose.  However, the WebAssembly version should be somewhat faster than the JavaScript version of yaAGC.
2021-04-22
Updated the description of yaYUL command-line switches to include the --reconstruction switch, whose was merged today from the "comanche67" branch of the GitHub repository into the main branch.
2021-04-21
I decided to follow up on yesterday's improvements to the modern assembler's (yaYUL) sorting of symbol tables.  I've revised the format of the symbol tables so that they end up being much easier to compare them side-by-side with the original symbol tables created by the YUL/GAP assemblers.  The reason one would want to do that, it has been pointed out to me, is that comparison of properly-sorted symbol tables makes it much easier to detect and correct misprints of symbol names in the transcribed AGC source code.  For example, the difference between symbols like POO (pee oh oh) and P00 (pee zero zero) may not be very apparent visually a digitized printout, and won't affect the assembled ropes if misspelled consistently in any given version of an AGC program, but will be very obvious in a properly-sorted symbol table since a misspelled symbol will appear at a completely different place in the table.  Plus, it's just kind of nice when the output from yaYUL is a little more consistent with YUL and GAP.

The source code for yaYUL now in the github repository has these changes to the symbol-table formatting in it.

Besides that, an effort to find misspelled symbols in the transcribed AGC source code is actually underway right now, using just the methods I mentioned.  I'm not doing this personally, as it preceded the symbol-table changes in yaYUL.  (Various folks have amused themselves over the course of time by creating AGC assemblers of their own, rather than using yaYUL, and some of them were cleverer than I in formatting the symbol tables.  )  At any rate, I don't see much reason to update the colorized, syntax-highlighted AGC source code on this site until at least a first pass on searching-and-destroying those misspelled symbols has been completed, and thus I haven't done so as of yet.  Hopefully that will be in the not-too-distant future.  Anyone who's particularly interested can follow the effort by reading issue #1141 in our github repository.
2021-04-20
  • The link on the Luminary page to the raw scans for the listing of RETREAD 44 was incorrect (it pointed to AURORA 12), and has been fixed.
  • The assembler (yaYUL) in the github repository can now produce symbol tables of assembled AGC code using the collation order of the original Apollo-era assemblers.  Up to now, it has simply been using the native collation (presumably ASCII) of the platform on which yaYUL is being run.  Symbol-table files (*.symtab) that yaYUL creates for use with a debugger remain in the native order, since otherwise the debugger might not be able to interpret them properly.  The original YUL assembler, however, used the native character encoding of the Honeywell H-800 computer system on which it ran, and the printed symbol tables in the assembly listings it created were in that collating order.  Likewise, the original GAP assembler which succeeded YUL used the native IBM character encoding, namely EBCDIC, for sorting symbol tables.  Thus, while the assembly listings created by yaYUL had all the same symbols as those created by YUL or GAP, the symbols were in a different order, and the symbol tables were consequently difficult to compare.  In general, after today's update, all versions of the RETREAD, AURORA, SUNBURST, TRIVIUM, and SOLARIUM programs were originally assembled with YUL and now use yaYUL's H-800 ordering, while all other versions of AGC programs that are available to us were originally assembled with GAP and now use the EBCDIC ordering.  Admittedly, I haven't checked the new assembly listings vs the original scans in full detail, since the combined symbol tables of all the AGC versions we now have available undoubtedly total more than 100,000 symbols.  Yikes!  Nevertheless, even if there are some errors, I'm sure yaYUL's symbol-table ordering is very close to being correct.  The colorized HTML versions of the AGC source code here at the Virtual AGC website don't yet reflect the H-800/EBCDIC ordering, because some corrections to the AGC code base are in the works and I'd like to avoid unnecessary churn.  Once the HTML listings are updated, however, their symbol table ordering will hopefully match those of the scanned original assembly listings.
2021-03-30
Several new documents have been added to the library:
Thanks to Mike Stewart for the first two documents, and to the Computer History Museum for the final document.
2021-03-27
Continued adding mission reports and their supplements to the "Mission Report" section of our document library page.  I expanded the section to include a number of postflight trajectory documents as well.  Over the past couple of days, the documents added to that section have so outnumbered the handful which were present originally that the icon I typically put on newly-added library documents had become pointless.  When the icons were there, it just appeared as though every document was new.  Since the icons weren't helpful under these circumstances, I've temporarily removed all of them in that section of the library.
2021-03-26
I have found out somewhat belatedly that "Apollo X Mission Report" documents actually contain useful info vis-à-vis the guidance system, including for example some postflight trajectory data.  While we already had a "Mission Report" section of our document library page, I have now examined that section with new eyes and found it severely deficient.  Anyway, I've pepped up that section of the library considerably, adding so many documents that it hardly even seems like the same section any longer.  (I don't claim that this pepping up has any great value, since all the documents I added were online elsewhere; all anybody had to do was google them.  But still, it's nice to have stuff collected in one place.)  There are still various missing supplements to the mission reports that I haven't yet made any effort yet to find, so the section may still undergo some expansion in the future.
2021-03-25
2021-03-24
Added the first half of section 5 (guidance equations) of the Comanche 72 (Apollo 13 CM) GSOP to the document library, from a scan at UHCL.  Fortunately, section 5 has only three PCR/PCN's, but the missing half of the document will nevertheless likely be seriously inconvenient if/when we're ever in a position to reconstruct Comanche 72's source code.  The "good" news is that the Comanche 67 reconstruction, which is a prerequisite for reconstructing 72, is seriously languishing right now, so there's no immediate need for the 2nd half of the Comanche 72 document.
2021-03-22
Updated instructions on building Virtual AGC from source for MacOS X, due to the fact that (I'm told) the old instructions no longer work on newer Mac versions.  The essential difference is that wxWidgets 3.1.x (and eventually 3.2) must be used rather than 2.8 or 3.0.  Linux build-from-source instructions have also been so updated with optional use of wxWidgets 3.1/3.2, although 2.8 remains the recommended version.  Exploiting this update requires the latest Virtual AGC source code.
2021-03-21
The instructions for building Virtual AGC from source code have been updated to include Slackware 14.2 and Chromebooks.  Thanks to Nick Warne for the info!  (I haven't actually personally tried those platforms.  So many platforms ... so little time.)
2021-02-07
Building on what I said in yesterday's post, Dan Kosko has also sent in a couple other docs, now added to our library page:
  • The Saturn V Flight Manual for SA-504, thus adding to the collection we already had of Saturn IB and Saturn V (SA-503, SA-507) flight manuals.
  • An improved (or at any rate different) scan of the Lunar Excursion Module Familiarization Manual.  The thing that stands out about the new scan (as opposed to the old one) is that some attempt was made to rejoin wide drawings that the first scan had left as separate frames.  For example, in the old scan, Figure 3-3 comprises PDF pages 50-52, while in the new scan it's simply page 41.  But the effort to rejoin the drawings wasn't consistent, so you can certainly find some large drawings in the new scan that still show up as 2 or more frames.  For example, in the new scan, Figure 3-26 is 3 pages (PDF 91-93).  Even at that, in the old scan Figure 3-26 is 5 pages (PDF pages 122-126).  Yikes!  So one can't really complain too hard.
2021-02-06
Apologies for the infrequent site updates.  I've been involved for quite a while in a possibly-futile attempt to reconstruct Comanche 67 (Apollo 12 CM AGC software); it's making progress, but it's slow, Slow, SLOW, which is why there's never any news about it. 

We do have a new website addition, though, in the form of a document added to our electro-mechanical page (as opposed to our document-library page).  It's North American Aviation's "CSM Functional Integrated System Schematics, Block II".  This is a doc I found several years ago at the U.S. Space & Rocket Center archives, but ended up failing to get digitized.  Dan Kosko (thanks, Dan!) has followed up on it, finding that the University of Alabama, Huntsville, (thanks, UAH!) had made a beautiful scan of it a decade ago, years before my own unsuccessful efforts to get it.
2021-01-15
Paul Koning has sent me some feedback on our How to Digitize page, in which he chides me for recommending the use of the JPG file format for storing, as opposed to lossless image-file formats such as PNG.  I've updated the page both to clarify the conditions under which I recommend JPG vs PNG, and to point out that every recommendation I make is probably obsolete anyway, now that relatively cheap book scanners (overhead scanners) are on the market.
2021-01-12
17 years ago, Sandy Brown, then associated with David Mindell's now-defunct HRST website, sent me a finding aid he had made for AGC-related materials he had found at the MIT Museum, some of which were used as part of the foundation for HRST.  For some reason, I apparently didn't think to post his finding aid online and forgot all about it.  A few years ago, Debbie Douglas, the MIT Museums' curator, sent me this list, which I didn't recall ever having seen before, and once again I didn't post it online.  Last year, she sent the list to Mike Stewart, who sent it to me again, at my request.  Yet again, I apparently didn't post the thing online!  Or at least, I've just spent 20 minutes scouring everywhere before finally finding it (in my email, not online).  So if I had put it online, it's well hidden.  Well, the fourth time's the charm, I hope, and it now has an entire, one-sentence-long section on our website page about finding material.  It can't be missed now.  Maybe.

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