Introduction

Most of the remainder of this website, other than this page (and the companion page, MIT/IL Engineering Drawing Index), is devoted to the software for the Apollo Guidance Computer (the AGC).  In various pages of the site we talk a lot about the software that ran on the AGC, about the software that originally prepared the AGC's flight software software for actual use, about the documentation for the AGC's software, about our modern open-source replacements for that preparation software, about our open-source software for simulating the behavior of the AGC and its display/keyboard peripheral (the DSKY), about the integration of our AGC simulation software into modern spaceflight-simulation software, about the people who originally coded the software, and so on.  In other words, Software, software, software, and then more software, for dessert!

Admittedly, there are a few places on the site where we change course a bit to discuss the AGC and DSKY hardware, mainly to discuss various people's personal projects to make modern hardware recreations of the AGC and/or DSKY.  All of those efforts derive, in some sense from John Pultorak's original attempt to provide a simulation of the Block I AGC.  But when we provide this material, we don't really go into detail, and simply let people speak in their own words about whatever they're willing to share, and then direct you to their own websites (if any) or caches of photographs or movies of their equipment in action.  That approach has some drawbacks, though, since people may not choose to share their design files, may (and usually do) work in some kind of electrical or mechanical design environment that's congenial to them but which the rest of us don't have the financial resources or inclination to duplicate, and of course, never give you actual access to their hardware creations; if you want access, you have to build one yourself!

On this page, though, we change course quite a lot, and provide a lot of resources related to the AGC/DSKY hardware.  Too much, perhaps!  As with our software efforts, of course, this is an ongoing effort that will probably never be 100% complete.  But here, briefly, is what we trying to provide for you on this "electro-mechanical" page.

Once all of this material is in place, so what?  Well, there's a lot of interesting stuff you can do with it if you're so inclined:

Because this is a work in progress, though, you may not see all of this material available just yet.  Just have a bit of patience.

What about the mechanical design?  After all, I've barely mentioned it after first bringing it up.  It's just that our mechanical effort hasn't advanced very far yet, due to the effort poured so far into the electrical effort.  The roadmap for the mechanical effort will be this, when the time comes:  provide scans of all original mechanical drawings, visually-accurate transcription into some open 2D CAD format (probably DXF), and mechanically-accurate reworking into some open 3D-model format (if/when an appropriate format exists).

Contents

Sources of Information

The official AGC/DSKY electro-mechanical drawings available to us at the present time are these:

All of this material is hosted locally here at the Virtual AGC Project website, or else at out Internet Archive Virtual AGC site.  The best portal into this mass of available original Apollo Program engineering drawings is through our MIT/IL Apollo engineering-drawing index page.

Besides these primary sources, there are additional (sometimes overlapping) essentially complete electrical schematics available in:
These documents are theory-of-operation documents, which describe the circuits textually and often provide useful information like timing diagrams of what the circuits do.  In the process of providing this info, though, they provide the schematics themselves as figured embedded within the text.  In saying that the schematics provided in the theory-of-operation documents are "essentially complete", what I mean is that the schematics in these volumes aren't precisely in the form of the original drawings, but rather have been redrafted by AC Electronics to fit into the format of their volumes.  Thus, they are subject to mistakes (and potentially, corrections) by AC Electronics, and cannot necessarily be straightforwardly matched to specific drawing numbers or revisions.

Surprisingly, while we have schematics in one form or another for all AGC/DSKY modules, though not necessarily in all of the different forms or versions we like, and we have wiring diagrams for the DSKY backplane into which its modules are inserted, we do not have wiring diagrams for the AGC backplane.  (See this section for a discussion of how the AGC circuitry is partitioned up.)  Nevertheless, we do have enough information about it to be useful, compiled by two techniques:  Firstly, the electrical schematics for the individual circuit modules list "net names" for all of the connector pins going from the module to the backplane, so we do know how the modules were interconnected on the backplane; secondly, physical AGCs can have their backplanes mapped by means of continuity checking with an ohmmeter.  Mike Stewart has put together a helpful sqlite database and an interactive, online form of it, based on mapping out the backplane for AGC s/n 14.

Other useful resources may be available in the "AGC electrical schematics" section of our document-library page.

Besides the AGC Handbook, additional information used for cross-referencing the various drawings to specific AGC or DSKY part numbers and/or serial numbers came from a couple of sources:

Versioning the AGC and DSKY

"Versions" of the AGC and DSKY? Huh?  This is not a concept mentioned elsewhere on the site, other than the fact that there were earlier "Block I" and later "Block II" versions of everything.

Well, like the AGC's software, the AGC's hardware (electrical and mechanical design) evolved over time.  For example, not all AGC electrical schematics are created equal ... you have to know which specific AGC model number you're interested in, since its electrical schematics and mechanical configuration may be different than other AGC models.  There were a lot of different versions of the AGC over time.  The same comment goes for DSKY units (and other components as well, though we won't concern ourselves with any of them).  The good news is that the changes were prior to any actual missions, and mostly didn't affect software, so there was much less variation in electrical design from mission to mission than there was for the software design.

The AGC and DSKY part-numbering scheme looked like this:

PARTNUMBER-DASHNUMBER REVISION

For example, Block II AGCs had PARTNUMBERs 2003100, 2003200, and 2003993, with DASHNUMBERs like -011, -021, -031, and so on.  REVISIONs were letter codes, such as A, B, C, etc., or else a dash (-) for "no revision".  For example,

2003200-011A

Given a part number for a particular AGC (or DSKY) model, the part number then relates to a set of sub-assemblies (often represented by electrical schematics or mechanical drawings), many of which are circuit modules, which themselves may have varying versions over time, and have part-numbers like

PARTNUMBER REVISION

For example, the AGC with p/n 2003200-011A contained, among other things, an "oscillator module" which fit into a backplane socket labeled B7, and which itself had a p/n 2005003E ... and naturally, we have drawing 2005003E if you want to see it.

Sadly, in most cases, though with some happy rare exceptions, we don't presently have enough information to actually tell you which versions of every AGC or DSKY flew on which missions.  Oddly, even though we don't know their part numbers, we do have enough information to know which serial numbers of AGC and DSKY units flew on which missions.  That information is given in an Appendix

In general, we think that all Block II missions flew with some variant of AGC p/n 2003993-xxx and DSKY p/n 2003994-xxx, but irritatingly we presently have only partial drawing sets for part numbers 2003993 and 2003994!  Whereas we have complete drawing sets for the earlier Block II AGC part numbers (2003100 and 2003200) and DSKY part numbers (2003985 and 2003950).  This would naturally lead one to ask how great the differences were between all these different AGC part numbers?  Well, Mike Stewart has put together a nice, little list of the differences we're aware of; I quote him:

Changes from AGC p/n 2003100 to 2003200:

Changes from AGC p/n 2003200 to 2003993:

In particular, it sounds like the biggest change from AGC p/n 2003200 to 2003993 was the support for the Raytheon Auxiliary Memory Unit.  Over on our LUMINARY page, we actually have a complete AGC program whose purpose is exercising and testing this very Auxiliary Memory Unit.  Nevertheless, the Auxiliary Memory Unit was neither installed nor used on actual missions, so I think you'd be justified in believing that the 2003200 AGC is pretty close to being a 2003993 AGC.

In other words, with few exceptions, most Block II AGC software that we have should run on any of the Block II AGC/DSKY models to which we're likely to be able to get.  Similarly, though Mike doesn't address it above, the same is true of the Block I AGC software we have and the Block I AGC electrical schematics we have.

CAD Files and Images

In addition to providing scans of original electrical and mechanical drawings from the Apollo program, there is an ongoing effort to transcribe these drawings into CAD files.

Such CAD transcriptions are made as faithfully visually to the original as is feasible, given the capabilities of the CAD program involved, as long as there is no compromise of electrical or mechanical correctness.  But realize that transcription is a human effort, so transcribed CAD files may at first contain errors; conversely, they may from time to time correct errors present in the original drawings — naturally, though, with suitable notes indicating that the change had been made, and why.  It has also been possible occasionally to reconstruct some currently-missing drawings from the original Apollo Program.

Help in proof-reading CAD vs the original drawings is welcomed, and you can contact me directly at the address at the bottom of this page if you're interested.  This does not require using CAD or having expert electrical knowledge.  It just involves comparing two images like the ones below and seeing how they differ from each other (click to enlarge):

Click to enlarge  Click to enlarge

No mechanical drawings have yet been transcribed to CAD, so I presently have no thoughts to pass along to you about it, or even know what CAD system will be used.  (I can assure you, though, that it will be open-source, free-of-charge software, as opposite to some undoubtedly-better, proprietary, expensive software.)

As far as electrical CAD files are concerned, though, the open-source KiCad electrical-design software is used.  It is available, for free of course, on Windows, Mac OS X, and all of the major flavors of Linux.  The electrical schematics which have been transcribed into CAD, or are in the process of being transcribed, are stored in the "schematics" branch of our GitHub repository.

There's plenty of online material to help you get started with KiCad, if you're inclined to do anything more with the CAD files as such.  Here's the executive summary of what you need to know if you want to specifically work with our electrical schematics in KiCad:

Digital Simulation of the AGC Electronic

Surprisingly, digital simulation of the electronics turns out not to be incredibly difficult.  Nevertheless, discussion of the topic can be rather involved, so to keep this page relatively short (really!), a separate page is devoted to discussing digital simulation.

Basic Partitioning of the AGC Electronics

(This section is under construction, is incomplete, and is very likely full of really dumb errors.)

The Block II or LM AGC contains two trays of electronics, the A-tray and the B-tray.

The trays contain connectors allowing A to be connected to B, or vice-versa, and to the outside world.  Each tray also contains a "backplane" into which electronics modules can be plugged.  The A-tray modules have designations like A1, A2, ..., A31, while the B-tray modules have designations like B1, B2, ..., B17.

Each of these modules has an associated drawing.  For example, in the 2003200-011 AGC, module A1 (the "scaler" module) has electrical drawing 2005259A.  In other words, each module is considered to comprise a single circuit, with a unique (though possibly multi-sheet) drawing.

Modules A1 - A24 consist entirely of "logic": i.e., their electrical drawings consist entirely of NOR-gates and the connectors for plugging the modules into the backplane.    For this reason, I suppose, the drawings aren't called "schematics", but are given the special name "LOGIC FLOW DIAGRAMS".  But they're schematics anyway.  Modules A25 - A31 and B1 - B17 are entirely analog in nature and are specifically called "SCHEMATICS".

As far as the construction of the circuitry is concerned, three basic techniques were intermixed:

Module with nickel-ribbon logic



Of course, these details don't matter much in modern terms unless you're very enthusiastic about building an AGC recreation and want to do it absolutely 100% authentically.  If you were, you would be defeated in the end by the fact that the electronic components originally used, such as the dual triple-input NOR gates, are no longer available in precisely the form they were originally used.  And while I haven't priced ferrite memory lately, I expect that it's probably not terribly cost-effective.    Though, surprisingly, you can get junked ferrite-memory systems from eBay; not from the AGC, naturally, but perhaps close enough that they could be made to work if mined for parts.

The pictures in this section, taken by Mike Stewart, are of Jimmie Loocke's model 2003100-071 AGC, s/n 14.

Drawings for Block I AGC

Drawings for Block I AGC p/n 1003700

1003700 seems to be the final form of the Block I AGC design.

We did not originally have the original electrical-schematic drawings for any Block I AGC, but we did have AC Electronics document ND-1021041 which contains AC's redrafted form of the schematics.  As a result, the CAD files referenced in this section may be a mixture of those made directly from the original drawings and those recovered instead from ND-1021041.  The latter are distinguished by having revision "r" for "recovered" or "regenerated" (or "ron" ) rather than the official revisions listed in the table below.


Some modules in an actual 1003700-011 AGC.  (Click to enlarge.)

In the drawing-number and schematic-drawing columns of the table below, the separate signal-wiring diagram cards are shown in parentheses.

Module Description
Drawing Number
Schematic Drawing
Comments
A1 - A16: Logic Flow Bit
1006540A

(1006120A)
Sheet 1/1
Related ND-1021041 Figures:

See also: Transcription of the ND-1021041 circuits to CAD or images rendered from CAD

A17: Logic Flow C
1006543D

(1006123C)
Sheet 1/1
Related ND-1021041 Figures:

See also: Transcription of the ND-1021041 circuits to CAD or images rendered from CAD

A18: Logic Flow B
1006542B

(1006122A)
Sheet 1/1
We don't have a scan of revision "B" of this drawing; scanned images are revision "-" instead.

Related ND-1021041 Figures:

See also: Transcription of the ND-1021041 circuits to CAD or images rendered from CAD

A19, A39: Interface
1005701B
Sheet 1/1
We don't have a scan of revision "B" of this drawing; scanned images are revision "A" instead.

Related ND-1021041 Figures:
A20, A40: Interface
1005702A
Sheet 1/1
We don't have a scan of revision "A" of this drawing; scanned images are revision "-" instead.

Related ND-1021041 Figures:
A21: Logic Flow S
1006556B

(1006136C)
Sheet 1/1
We don't have a scan of revision "B" of this drawing; scanned images are revision "A" instead.

Related ND-1021041 Figures:

See also: Transcription of the ND-1021041 circuits to CAD

A22: Logic Flow P
1006553F

(1006133A)
Sheet 1/1
We don't have a scan of revision "F" of this drawing; scanned images are revision "E" instead.

Related ND-1021041 Figures:
A23: Logic Flow E
1006545-

(1006125-)
Sheet 1/1
Related ND-1021041 Figures:
A24: Logic Flow R
1006555B

(1006135A)
Sheet 1/1
We don't have a scan of revision "B" of this drawing; scanned images are revision "A" instead.

Related ND-1021041 Figures:
A25: Logic Flow Q
1006554A

(1006134-)
Sheet 1/1
We don't have a scan of revision "A" of this drawing; scanned images are revision "-" instead.

Related ND-1021041 Figures:
A26: Logic Flow J
1006549B

(1006129A)
Sheet 1/1
Related ND-1021041 Figures:

See also: Transcription of the ND-1021041 circuits to CAD or images rendered from CAD

A27: Logic Flow D
1006544D

(1006124A)
Sheet 1/1
We don't have a scan of revision "D" of this drawing, and our scan of revision "C" is extremely blurry; scanned images are revision "B" instead.

Related ND-1021041 Figures:
A28: Logic Flow N
1006552B

(1006132A)
Sheet 1/1
We don't have a scan of revision "B" of this drawing; scanned images are revision "A" instead.

Related ND-1021041 Figures:

See also: Transcription of the ND-1021041 circuits to CAD or images rendered from CAD

A29: Logic Flow V
1005763-

(1006139B,
1005761-)
Sheet 1/1
The Block I index in the AGC Handbook indicates that the correct drawing is 1005763-.  However, ND-1021041 (Table 8-III), which we believe relates to AGC 1003700, lists drawing 1006559 instead.  We don't have a scan of 1005763, but do have several revisions of 1006559.  The newest revision, 1006559D, is the scanned image used here.

Related ND-1021041 Figures:
A30 - A31: Logic Flow H
1006548B

(1006128A)
Sheet 1/2
Sheet 2/2
We don't have a scan of revision "B" of this drawing; the highest revisions we have are revision "A" of sheet #1 and revision "-" of sheet #2.

Related ND-1021041 Figures:
A32: Logic Flow F
1006546A

(1006126A)
Sheet 1/1
Related ND-1021041 Figures:
A33 - A34: Logic Flow G
1006547H

(1006127B)
Sheet 1/1
We don't have a scan of revision "H" of this drawing; scanned images are revision "G" instead.

Related ND-1021041 Figures:

See also: Transcription of the ND-1021041 circuits to CAD or images rendered from CAD

A35: Logic Flow A
1006541B

(1006121A)
Sheet 1/1
Related ND-1021041 Figures:
A36: Logic Flow T
1006557E

(1006137A)
Sheet 1/1
We don't have a scan of revision "E" of this drawing; scanned images are revision "D" instead.

Related ND-1021041 Figures:
A37: Logic Flow L
1006560A

(1006130A,
1006145-)
(1006560) Sheet 1/1

(1006550) Sheet 1/1
The Block I index in the AGC Handbook indicates that 1006560A is the correct drawing.  However, ND-1021041 (Table 8-III), which we believe relates to AGC 1003700, lists drawing 1006550 instead.  We don't 1006560A, but we do have 1006560-.  And we have several revisions of 1006550, of which revision "F" is the newest.

Related ND-1021041 Figures:
A38: Logic Flow M
1006551B

(1006131)
Sheet 1/1

(Sheet 1/1)
We don't have a scan of revision "B" of this drawing; scanned images are revision "-" instead.

Related ND-1021041 Figures:
A39: Interface
(See A19)

(See A19)
A40: Interface
(See A20)

(See A20)
B1: TBD
TBD

Related ND-1021041 Figures: None
B2 - B4: Power Switch Module
1006097G
Sheet 1/1
We don't have a scan of revision "G" of this drawing; scanned images are revision "F" instead.

Related ND-1021041 Figures:
B5: Filter
1005700B
Sheet 1/1
We don't have a scan of revision "B" of this drawing; scanned images are revision "A" instead.

Related ND-1021041 Figures:
B6: AGC Clock Osc
1006140M
Sheet 1/3
Sheet 2/3
Sheet 3/3
We don't have a scan of revision "M" of this drawing; scanned images are revision "L" instead.

Related ND-1021041 Figures:
B7: Driver Service
1006082G
Sheet 1/1
We don't have a scan of revision "G" of this drawing; scanned images are revision "F" instead.

Related ND-1021041 Figures:
B8: Current Switch
1006074C
Sheet 1/2
Sheet 2/2
We don't have a scan of revision "C" of this drawing; scanned images are revision "B" instead.

Related ND-1021041 Figures:
B9: Erasable Memory Stick
1006061D
Sheet 1/1
We don't have a scan of revision "D" of this drawing; scanned images are revision "C" instead.

Related ND-1021041 Figures:
B10 - B11: Erasable Drivers
1006086G
Sheet 1/1
We don't have a scan of revision "G" of this drawing; scanned images are revision "F" instead.

Related ND-1021041 Figures:
B12: Power Supply Control
1006098J
Sheet 1/1
We don't have a scan of revision "J" of this drawing; scanned images are revision "H" instead.

Related ND-1021041 Figures:
B13 - B14: Erasable Sense Amplifiers
1006187B
(1006187) Sheet 1/1

(1006118) Sheet 1/1
The Block I index in the AGC Handbook indicates that the correct drawing is 1006187B.  However, ND-1021041 (Table 8-III), which we believe relates to AGC 1003700, lists drawing 1006118 instead.  We do not have 1006187A, but we do have 1006187A.  Also, we have several revisions of 1006118, of which the latest is 1006118F.

Related ND-1021041 Figures:
B15 - B20: TBD
TBD

Related ND-1021041 Figures:  None
B21 - B24, B28 - B29: Rope Memory
1006144-
Sheet 1/2
Sheet 2/2
Revisions "A", "B", "C", and "D" of this drawing all exist, so it is surprising that revision "-" is called out by the AGC Handbook.  Unfortunately, these sheets were each split into 3 or 4 pieces in order to be photographed and stored, and we do not have all of the pieces for either rev "-" or rev "A" of the 2nd sheet.  The links to the scanned images at left are to rev "-" of the first sheet of the drawing, and to rev "B" of the second sheet.

Related ND-1021041 Figures:
B25: TBD TBD
Related ND-1021041 Figures: None
B26 - B27: Rope Sense Amplifiers
1006119E Sheet 1/1
We don't have a scan of revision "E" of this drawing; scanned images are revision "D" instead.

Related ND-1021041 Figures:
B28 - B29: Rope Memory
(See B21 - B24)

(See B21 - B24)
B30: Rope Strand Select
1006099B
Sheet 1/1
We don't have a scan of revision "B" of this drawing; scanned images are revision "A" instead.

Related ND-1021041 Figures:
B31: Strand Gate
1006199A
Sheet 1/2
Sheet 2/2
We don't have a scan of revision "A" of this drawing; scanned images are revision "-" instead.

Related ND-1021041 Figures:
B32 - B33: Rope Driver
1006147C
Sheet 1/2
Sheet 2/2
We don't have a scan of revision "C" of this drawing; scanned images are revision "B" instead.

Related ND-1021041 Figures:


Drawings for Block I Main DSKY

Drawings for Block I Main DSKY p/n 1003707

Module Description
Drawing Number
Schematic Drawing
Comments
Interconn Diag Main DSKY 1005766-
1006165E
Sheet 1/2
Sheet 2/2
The latest scan presently available is for drawing 1006165D.
D1 - D3: Decoding
n/a
n/a
Modules D1-D3 are NAV DSKY only.
D4 - D6: Decoding
1006162C
Sheet 1/3
Sheet 2/3
Sheet 3/3
The latest scan presently available is for drawing 1006162B.

Related ND-1021041 Figures:
D7 - D10: Relays n/a
n/a
Modules D7-D10 are NAV DSKY only.
D11 - D14: Relays
1006161D
Sheet 1/1
The latest scan presently available is for drawing 1006161C.

Related ND-1021041 Figures:
D15: Power Supply
n/a
n/a
Module D15 is NAV DSKY only.
D16: Power Supply
1006163H
Sheet 1/1
The latest scan presently available is for drawing 1006163G.

Related ND-1021041 Figures:
D17: Keyboard
n/a
n/a
Module D17 is NAV DSKY only.
D18: Keyboard
1006150E

Related ND-1021041 Figures:
Interconn Flow Main DSKY
1005767-
1006166D
Sheet 1/4
Sheet 2/4
Sheet 3/4
Sheet 4/4
We do not have 1005767.  The latest rev of 1006166 we have is C.
G&N Failure Detect
1005730C
Sheet 1/1
The latest revision we have is 1005730B.

Drawings for Block I Main DSKY p/n 1003563

1003563 seems to have been the final design for the Block I main DSKY.

   
Internal views of a 1003563-051 AGC.  (Click to enlarge.)

Module Description
Drawing Number
Schematic
Drawing
Comments
Interconn Diag Main DSKY 1005753A Sheet 1/2
Sheet 2/2
The newest revision we have is 1005753-.
D1 - D3: Decoding
n/a
n/a
Modules D1-D3 are NAV DSKY only.
D4 - D6: Decoding
1005762-
(Do not have)

D7 - D10: Relays
n/a n/a Modules D7-D10 are NAV DSKY only.
D11 - D14: Relays
1005780-
Sheet 1/1

D15: Power Supply
n/a
n/a
Module D15 is NAV DSKY only.
D16: Power Supply
1005756A
Sheet 1/1

D17: Keyboard
n/a
n/a
Module D17 is NAV DSKY only.
D18: Keyboard
1005784- (Do not have)

Interconn Flow Main DSKY
1005770-
(Do not have)

G&N Failure Detect
1005730C
Sheet 1/1
The latest revision we have is 1005730B.

Drawings for Block I Navigation DSKY

Drawings for Block I Navigation DSKY p/n 1003706

1003706 seems to have been the final form of the Block I navigation DSKY design.

Module Description
Drawing Number
Schematic Drawing
Comments
Interconn Diag Nav DSKY 1005764-
1006164C
Sheet 1/1
We do not have drawing 1005764.  The newest rev we have of 1006164 is B.
D1 - D3: Decoding
1006162C
Sheet 1/3
Sheet 2/3
Sheet 3/3
The latest scan presently available is for drawing 1006162B.

Related ND-1021041 Figures:
D4 - D6: Decoding
n/a
n/a
Modules D4-D6 are MAIN DSKY only
D7 - D10: Relays
1006161D
Sheet 1/1 The latest scan presently available is for drawing 1006161C.

Related ND-1021041 Figures:
D11 - D14: Relays
n/a
n/a
Modules D11-D14 are MAIN DSKY only.
D15: Power Supply
1006163H
Sheet 1/1 The latest scan presently available is for drawing 1006163G.

Related ND-1021041 Figures:
D16: Power Supply
n/a
n/a
Module D16 is MAIN DSKY only.
D17: Keyboard
1006160F
Sheet 1/1
Related ND-1021041 Figures:
D18: Keyboard
n/a
n/a
Module D18 is MAIN DSKY only.
Interconn Flow Nav DSKY
1005765-
1006167C
Sheet 1/3
Sheet 2/3
Sheet 3/3
The latest rev we have for 1006167 is 1006167B.
G&N Failure Detect
1005730C
Sheet 1
The latest revision we have is 1005730B.

Drawings for LM/Block II AGC

Drawings for LM/Block II AGC p/n 2003100-021

This is an interesting version of the AGC, in that the logic circuitry was constructed in a very different fashion than later dash numbers of 2003100 (and the later versions 2003200 and 2003993) were.  Those later versions used multi-layer printed circuit boards to hold the integrated circuits, whereas this version interconnected them via a nickel ribbon.  The nickel-ribbon design turned out to have too much capacitance, resulting in excessive signal delay, and the design didn't function in practice.  This is what resulted in the introduction of multi-layer printed circuit boards instead.  That's not to say, of course, that there's anything wrong with the electrical schematics for this design, since the physical construction of the circuitry is basically outside the scope of the electrical schematics.  I'm told that all existing functional 2003100 AGC units are of the multi-layer printed-circuit variety.

In addition to the nickel-ribbon interconnect, the circuitry for the various modules was actually divided into four separate "quadrants" of circuitry, which were mostly rather independent but did have some interaction with each other.  Later designs removed the concept of quadrants altogether.

Besides the reference sources mentioned earlier, AC Electronics document ND-1021043 of March 10, 1966, supposedly relates to AGC p/n 203100-021 (according to its Tables 3-I and 7-I), and its Table 8-II lists all of the associated module drawings.  But I don't believe there are any differences between the circuitry it presents and that presented by ND-1021042.

In what follows, note that the schematic drawing is all that is needed for understanding the electronics as such.  Sometimes, though, there's also a "signal wiring diagram" listed.  These are related to the nickel-ribbon interconnect described above. To understand what that is and how to read it, consult the Appendix.  It should be noted that because of the later reworking of the design to replace the nickel-ribbon interconnect with a multi-layer printed circuit board, the reference designators and pin numbering from later versions is not closely related to numbering of this version of the design.

Module Description
Schematic Drawing
(Signal Wiring Diagram)
Comments
A1: Scaler Module
2005059E page 1, 2
(2005159C page 1, 2, 3, 4)

A2: Timer
2005060D page 1, 2, 3
(2005160C page 1, 2, 3, 4)
See also: transcription of drawing to CAD or images rendered from CAD
A3: S Q Register and Decoding
2005051D page 1, 2
(2005151B page 1, 2, 3, 4)

A4: Stage Branch Decoding
2005062C page 1, 2
(2005162D page 1, 2, 3, 4)

A5: Cross Point Generator I
2005061D page 1, 2
(2005161B page 1, 2, 3, 4)

A6: Cross Point Generator II
2005063F page 1, 2
(2005163B page 1, 2, 3, 4)

A7: Service Gates
2005052D (page 1, 2)
(2005152B page 1, 2, 3, 4)
The AGC Handbook, which we usually regard as authoritative, calls out drawing 2005252D here, and document ND-1021042 (which doesn't specify revision numbers) calls out simply 2005252.  But you'll notice that what we've actually linked to is document 2005052D instead.  As it happens, we don't have a copy of drawing 2005252D to look at, but we do have earlier revisions of it, so we have a pretty good notion of what the drawing says.  It seems unlikely that any revision of 2005252 was used in the 2003100, because the known revisions of the drawing allow for features (expander gates, FAP power input) which were not even present in the 2003100 AGC. 

Currently, we think that what is really meant is drawing 2005052D.  This unfortunately means that both the AGC Handbook and document ND-1021042 have identical misprints in them, but that's not necessarily unlikely, since the data in ND-1021042 was likely extracted from the AGC Handbook in the first place.  Document ND-1021043 Table 8-II does list drawing 2005052 for module A7, as would be expected.
A8: 4 Bit Module
2005055D page 1, 2
(2005155B page 1, 2, 3, 4)

A9: 4 Bit Module
2005056C page 1, 2
(2005155B page 1, 2, 3, 4)

A10: 4 Bit Module
2005057E page 1, 2
(2005155B page 1, 2, 3, 4)

A11: 4 Bit Module
2005058D page 1, 2
(2005155B page 1, 2, 3, 4)

A12: Parity and S Register
2005053 page 1, 2
(2005153C page 1, 2, 3, 4)

A13: Alarms
2005069E
(2005169C page 1, 2)
We do not have a copy of signal wiring diagram 2005169C, but do have a copy of 2005169B (page 1, 2).  It's possible that there's a misprint in the AGC Handbook (which is what leads us to believe that it should be 2005169C), and that 2005169B may be correct.
A14: Memory Timing and Addressing
2005064F page 1, 2
(2005164C page 1, 2, 3, 4)

A15: RUPT Service
2005065D page 1, 2
(2005165C page 1, 2, 3, 4)

A16: In/Out I
2005066D page 1, 2
(2005166B page 1, 2, 3, 4)

A17: In/Out II
2005067B page 1, 2
(2005167- page 1, 2, 3, 4)

A18: In/Out III
2005068C page 1, 2
(2005168A page 1, 2, 3, 4)

A19: In/Out IV
2005070E page 1, page 2
(2005170- page 1, 2, 3, 4)

A20: Counter Cell I
2005054C page 1, 2
(2005154A page 1, 2, 3, 4)

A21: Counter Cell II
2005050J page 1, 2, 3
(2005150C page 1, 2, 3, 4)

A22: In/Out V
2005071B page 1, 2
(2005171- page 1, 2, 3, 4)

A23: In/Out VI
2005072C page 1, 2
(2005172- page 1, 2, 3, 4)
Alas! we do not have a copy of the signal wiring diagram for module A23.  Note, though, that the corresponding schematic drawing for AGC p/n 2003993 (namely drawing 2005272A page 1, 2), unlike the schematic drawing 2005072C here, explicitly shows pin numbers for the NOR-gate inputs and outputs.  Since the two versions of the A23 module circuitry are likely to be very similar, and since the pin numbering is one of the two important pieces information you can get from the signal wiring diagram, much of what the signal wiring diagram provides us can be recovered from that later schematic drawing anyway.  The other piece of information the signal wiring diagram provides, namely which of the specific NOR gates are packaged together into dual-NOR devices, cannot be recovered from the later schematic drawing, and thus currently remains a mystery.
A24: In/Out VII
2005073A page 1, 2
(2005173A page 1, 2, 3, 4)

A25 - A26: Interface
2005021C See also: transcription of drawing to CAD or images rendered from CAD
A27 - A29: Interface
2005020B page 1, 2

A30 - A31: Power Supply
2005010F page 1, 2

A52: Restart Monitor
2003305B
The drawing number and revision required are not actually known.  This is the only version of the restart-monitor circuit we're aware of.

See also: transcription of drawing to CAD or images rendered from CAD
B1 - B6: Rope Memory
2005012B page 1, 2
Note that this is a J-size (96"×34") drawing, with somewhat smaller text than other drawings, so this may affect choice of paper sizes for making physical printouts.

See also: transcription of drawing to CAD or images rendered from CAD
B7: Oscillator
2005003E page 1, 2, 3 The connectorization of this module is rather weird, and may be clarified from this picture of the connectors of the module aside the backplane socket into which it plugs.  Basically, there are connector pins numbered 133-169, 202-204, 302-304, 502-504, 602-604, 628-629, and 733-769, though only a handful of these connector pins are actually used by the circuitry!

Related ND-1021042 Figures: 4-118
B8: Alarms
2005028A page 1, 2, 3
AC document ND-1021043 lists 2005008 instead, but we accept the AGC Handbook as authoritative.
B9 - B10: Erasable Drivers
2005915- page 1, 2
AC document ND-1021043 lists 2005004 instead, but we accept the AGC Handbook as authoritative.
B11: Current Switch
2005005D page 1, 2
See also: transcription of drawing to CAD or images rendered from CAD
B12: Erasable Memory
2005006-

B13 - B14: Sense Amplifier
2005914- page 1, 2
AC document ND-1021043 lists 2005002 instead, but we accept the AGC Handbook as authoritative.
B15: Strand Select
2005009A

B16 - B17: Rope Driver
2005913- page 1, 2
AC document ND-1021043 lists 2005000 instead, but we accept the AGC Handbook as authoritative.
Dual NOR Gate
2005011- page 1, 2
Drawing 2005011 does not represent circuitry that actually appears explicitly within the AGC or DSKY.  Rather, it is MIT/IL's helpful explanation of the internal structure of the dual-NOR-gate integrated circuits that are used in a number of the AGC circuits.

Drawings for LM/Block II AGC p/n 2003200-011

Module Description
Drawing Number
Comments
A1: Scaler Module
2005259A page 1, 2
Related ND-1021042 Figures: 4-120
See also: transcription of drawing to CAD or images rendered from CAD
A2: Timer
2005260A 1, 2, 3
Related ND-1021042 Figures: 4-119, 4-120, 4-122, 4-159
See also: transcription of drawing to CAD or images rendered from CAD
A3: S Q Register and Decoding
2005251A page 1, 2
Related ND-1021042 Figures: 4-122, 4-128, 4-129, 4-131, 4-132, 4-221
See also: transcription of drawing to CAD or images rendered from CAD
A4: Stage Branch Decoding
2005262A page 1, 2
Related ND-1021042 Figures: 4-130, 4-131, 4-132, 4-134, 4-135, 4-136, 4-152, 4-153
See also: transcription of drawing to CAD or images rendered from CAD
A5: Cross Point Generator I
2005261A page 1, 2
Related ND-1021042 Figures: 4-132, 4-134, 4-135, 4-147, 4-156
See also: transcription of drawing to CAD or images rendered from CAD
A6: Cross Point Generator II
2005263A page 1, 2
Related ND-1021042 Figures: 4-134, 4-135, 4-153, 4-200, 4-207
See also: transcription of drawing to CAD or images rendered from CAD
A7: Service Gates
2005252A page 1, 2
Related ND-1021042 Figures: 4-134, 4-143, 4-144, 4-145, 4-146, 4-148, 4-149, 4-152, 4-153, 4-153B, 4-155, 4-175
See also: transcription of drawing to CAD or images rendered from CAD
A8: 4 Bit Module
2005255- page 1, 2
Related ND-1021042 Figures: 4-142, 4-153A, 4-208
See also: transcription of drawing to CAD or images rendered from CAD
A9: 4 Bit Module
2005256A page 1, 2
Related ND-1021042 Figures: 4-142, 4-153A, 4-175
See also: transcription of drawing to CAD or images rendered from CAD
A10: 4 Bit Module
2005257A page 1, 2
Related ND-1021042 Figures: 4-142, 4-153A, 4-175
See also: transcription of drawing to CAD or images rendered from CAD
A11: 4 Bit Module
2005258A page 1, 2)
Related ND-1021042 Figures: 4-142, 4-175
See also: transcription of drawing to CAD or images rendered from CAD
A12: Parity and S Register
2005253A page 1, 2
Related ND-1021042 Figures: 4-122, 4-136, 4-142, 4-149, 4-150, 4-154, 4-155, 4-157
See also: transcription of drawing to CAD or images rendered from CAD
A13: Alarms
2005269-
Related ND-1021042 Figures: 4-120, 4-124, 4-159, 4-166, 4-221
See also: transcription of drawing to CAD or images rendered from CAD
A14: Memory Timing and Addressing
2005264A page 1, 2
Related ND-1021042 Figures: 4-141, 4-142, 4-155, 4-166, 4-200, 4-206, 4-207, 4-208, 4-218
See also: transcription of drawing to CAD or images rendered from CAD
A15: RUPT Service
2005265A page 1, 2
Related ND-1021042 Figures: 4-133, 4-141, 4-142, 4-153C, 4-155A, 4-163, 4-209
See also: transcription of drawing to CAD or images rendered from CAD
A16: In/Out I
2005266- page 1, 2
Related ND-1021042 Figures: 4-172, 4-176, 4-178, 4-179
See also: transcription of drawing to CAD or images rendered from CAD
A17: In/Out II
2005267A page 1, 2
Related ND-1021042 Figures: 4-155, 4-172, 4-174, 4-177, 4-178, 4-185
See also: transcription of drawing to CAD or images rendered from CAD
A18: In/Out III
2005268A page 1, 2
Related ND-1021042 Figures: 4-120, 4-124, 4-172, 4-173, 4-181, 4-186, 4-190, 4-218
See also: transcription of drawing to CAD or images rendered from CAD
A19: In/Out IV
2005270- page 1, 2
Related ND-1021042 Figures: 4-120, 4-124, 4-178, 4-182, 4-183, 4-184, 4-187, 4-189
See also: transcription of drawing to CAD or images rendered from CAD
A20: Counter Cell I
2005254- page 1, 2
Related ND-1021042 Figures: 4-164
See also: transcription of drawing to CAD or images rendered from CAD
A21: Counter Cell II
2005250- page 1, 2, 3
Related ND-1021042 Figures: 4-133, 4-164, 4-221
See also: transcription of drawing to CAD or images rendered from CAD
A22: In/Out V
2005271- page 1, 2
Related ND-1021042 Figures: 4-159, 4-180, 4-187, 4-190
See also: transcription of drawing to CAD or images rendered from CAD
A23: In/Out VI
2005272A page 1, 2
Related ND-1021042 Figures: 4-120, 4-153C, 4-172, 4-175, 4-178, 4-186, 4-189, 4-190
See also: transcription of drawing to CAD or images rendered from CAD
A24: In/Out VII
2005273A page 1, 2
Related ND-1021042 Figures: 4-120, 4-122, 4-124, 4-135, 4-153B, 4-159, 4-165, 4-166, 4-171, 4-175, 4-178, 4-190
See also: transcription of drawing to CAD or images rendered from CAD
A25 - A26: Interface
2005021C
See also: transcription of drawing to CAD or images rendered from CAD
A27 - A29: Interface
2005912B page 1, 2
See also: transcription of drawing to CAD or images rendered from CAD
A30 - A31: Power Supply
2005916A page 1, 2
See also: transcription of drawing to CAD or images rendered from CAD
A52: Restart Monitor
2003305B The drawing number and revision required are not actually known.  This is the only version of the restart-monitor circuit we're aware of.

See also: transcription of drawing to CAD or images rendered from CAD
B1 - B6: Rope Memory
2005012B page 1, 2 Note that this is a J-size (96"×34") drawing, with somewhat smaller text than other drawings, so this may affect choice of paper sizes for making physical printouts.

See also: transcription of drawing to CAD or images rendered from CAD
B7: Oscillator
2005003E page 1, 2, 3 The connectorization of this module is rather weird, and may be clarified from this picture of the connectors of the module aside the backplane socket into which it plugs.  Basically, there are connector pins numbered 133-169, 202-204, 302-304, 502-504, 602-604, 628-629, and 733-769, though only a handful of these connector pins are actually used by the circuitry!

Related ND-1021042 Figures: 4-118
See also: transcription of drawing to CAD or images rendered from CAD
B8: Alarms
2005922A page 1, 2, 3
The links are actually to drawing 2005922-, because we don't presently have a copy of drawing 2005922A.  In point of fact, though, there is a discrepancy in that document ND-1021042 calls out drawing 2005927 for AGC p/n 2003200, whereas the AGC Handbook calls out drawing 2005922A.  We believe the AGC Handbook is more authoritative (and we don't have a copy of drawing 2005927 anyway).

Related ND-1021042 Figures: 4-170
See also: transcription of drawing to CAD or images rendered from CAD
B9 - B10: Erasable Drivers
2005104B page 1, 2
The original Apollo Program drawing provided a lot of connectivity data in the form of a large table, rather than in the form of wiring.  Therefore, it's not really possible to make a CAD transcription of the drawing which is (at the same time) a good visual representation of the original and an electrically-valid representation of the design.  Two separate CAD transcriptions were created, one of them intended to be visually accurate (containing the original tabular connectivity information) and the other one electrically accurate (replacing the table with wiring).

See also: transcription of drawing to CAD or images rendered from CAD
B11: Current Switch
2005005D page 1, 2 See also: transcription of drawing to CAD or images rendered from CAD
B12: Erasable Memory
2005106-
Note that this is a J-sized drawing, with the original being on roughly a 92"×34" sheet.  The transcription to CAD was (mistakenly) onto an 80"×34" sheet.  Either of these is a factor in considering appropriate paper sizes for making physical printouts.  In scanning, we did not have access to the Apollo Program era's 92"×34" plot; our "original" was instead scanned from 3 overlapping reductions onto 8.5"×11" paper.  You may therefore expect that a landscape printout of the CAD renderings onto 11"×17" paper is at least as satisfactory (and likely much more so) than our scans of the original drawing.

See also: transcription of drawing to CAD or images rendered from CAD
B13: Sense Amplifier
2005920B page 1, 2
See the comments for module B9-B10 above.

The sense-amplifier modules B13 and B14 provide the only exception to the rule that the only integrated circuits used in the AGC were NOR gates.  These modules also used a few sense-amplifier integrated circuits, whose internals are depicted in a figure the Appendix.

See also: transcription of drawing to CAD or images rendered from CAD
B14: Sense Amplifier
2005919A page 1, 2
See the comments for module B13 above.

See also: transcription of drawing to CAD or images rendered from CAD
B15: Strand Select
2005924-
See the comments for module B9-B10 above.

See also: transcription of drawing to CAD or images rendered from CAD
B16 - B17: Rope Driver
2005100D page 1, 2
See the comments for module B9-B10 above.

See also: transcription of drawing to CAD or images rendered from CAD
Dual NOR Gate 2005011- page 1, 2 Drawing 2005011 does not represent circuitry that actually appears explicitly within the AGC or DSKY.  Rather, it is MIT/IL's helpful explanation of the internal structure of the dual-NOR-gate integrated circuits that are used in a number of the AGC circuits.

Drawings for LM/Block II AGC p/n 2003993

Note: For p/n 2003993-xxx, while we have lists of the drawing numbers, we don't presently have the documentation needed to tell which revisions of the drawings are needed.  Therefore, to avoid being misleading, the revision codes are listed in a separate column rather than being suffixed to the drawing number as usual.  In general, we've tried to use the drawing revisions Eldon Hall supplied, on the grounds that he likely thought they were the correct revisions.  But Eldon supplied only the drawings for the An modules, and not the Bn modules, so in those cases we instead use the latest revisions we've been able to find or reconstruct.

Module Description
Drawing Number
Drawing
Revision
Chosen
Comments
A1: Scaler Module
2005259 page 1, 2
A
Related ND-1021042 Figures: 4-120
See also: transcription of drawing to CAD or images rendered from CAD
A2: Timer
2005260 page 1, 2, 3
A
Related ND-1021042 Figures: 4-119, 4-120, 4-122, 4-159
See also: transcription of drawing to CAD or images rendered from CAD
A3: S Q Register and Decoding
2005251 page 1, 2
A
Related ND-1021042 Figures: 4-122, 4-128, 4-129, 4-131, 4-132, 4-221
See also: transcription of drawing to CAD or images rendered from CAD
A4: Stage Branch Decoding
2005262 page 1, 2
A
Related ND-1021042 Figures: 4-130, 4-131, 4-132, 4-134, 4-135, 4-136, 4-152, 4-153
See also: transcription of drawing to CAD or images rendered from CAD
A5: Cross Point Generator I
2005261 page 1, 2
A
Related ND-1021042 Figures: 4-132, 4-134, 4-135, 4-147, 4-156
See also: transcription of drawing to CAD or images rendered from CAD
A6: Cross Point Generator II
2005263 page 1, 2
A
Related ND-1021042 Figures: 4-134, 4-135, 4-153, 4-200, 4-207
See also: transcription of drawing to CAD or images rendered from CAD
A7: Service Gates
2005252 page 1, 2
A
Related ND-1021042 Figures: 4-134, 4-143, 4-144, 4-145, 4-146, 4-148, 4-149, 4-152, 4-153, 4-153B, 4-155, 4-175
See also: transcription of drawing to CAD or images rendered from CAD
A8: 4 Bit Module
2005255 page 1, 2
-
Related ND-1021042 Figures: 4-142, 4-153A, 4-208
See also: transcription of drawing to CAD or images rendered from CAD
A9: 4 Bit Module
2005256 page 1, 2
A
Related ND-1021042 Figures: 4-142, 4-153A, 4-175
See also: transcription of drawing to CAD or images rendered from CAD
A10: 4 Bit Module
2005257 page 1, 2
A
Related ND-1021042 Figures: 4-142, 4-153A, 4-175
See also: transcription of drawing to CAD or images rendered from CAD
A11: 4 Bit Module
2005258 page 1, 2
A
Related ND-1021042 Figures: 4-142, 4-175
See also: transcription of drawing to CAD or images rendered from CAD
A12: Parity and S Register
2005253 page 1, 2
A
Related ND-1021042 Figures: 4-122, 4-136, 4-142, 4-149, 4-150, 4-154, 4-155, 4-157
See also: transcription of drawing to CAD or images rendered from CAD
A13: Alarms
2005269
-
Related ND-1021042 Figures: 4-120, 4-124, 4-159, 4-166, 4-221
See also: transcription of drawing to CAD or images rendered from CAD
A14: Memory Timing and Addressing
2005264 page 1, 2
B
Here, we've chosen a later revision than the one supplied by Eldon Hall.  It differs only in the caption provided for one of the connector pins.

Related ND-1021042 Figures: 4-141, 4-142, 4-155, 4-166, 4-200, 4-206, 4-207, 4-208, 4-218
See also: transcription of drawing to CAD or images rendered from CAD
A15: RUPT Service
2005265 page 1, 2
A
Related ND-1021042 Figures: 4-133, 4-141, 4-142, 4-153C, 4-155A, 4-163, 4-209
See also: transcription of drawing to CAD or images rendered from CAD
A16: In/Out I
2005266 page 1, 2
-
Related ND-1021042 Figures: 4-172, 4-176, 4-178, 4-179
See also: transcription of drawing to CAD or images rendered from CAD
A17: In/Out II
2005267 page 1, 2
A
Related ND-1021042 Figures: 4-155, 4-172, 4-174, 4-177, 4-178, 4-185
See also: transcription of drawing to CAD or images rendered from CAD
A18: In/Out III
2005268 page 1, 2
A
Related ND-1021042 Figures: 4-120, 4-124, 4-172, 4-173, 4-181, 4-186, 4-190, 4-218
See also: transcription of drawing to CAD or images rendered from CAD
A19: In/Out IV
2005270 page 1, 2
-
Related ND-1021042 Figures: 4-120, 4-124, 4-178, 4-182, 4-183, 4-184, 4-187, 4-189
See also: transcription of drawing to CAD or images rendered from CAD
A20: Counter Cell I
2005254 page 1, 2
-
Related ND-1021042 Figures: 4-164
See also: transcription of drawing to CAD or images rendered from CAD
A21: Counter Cell II
2005250 page 1, 2, 3
-
Related ND-1021042 Figures: 4-133, 4-164, 4-221
See also: transcription of drawing to CAD or images rendered from CAD
A22: In/Out V
2005271 page 1, 2
-
Related ND-1021042 Figures: 4-159, 4-180, 4-187, 4-190
See also: transcription of drawing to CAD or images rendered from CAD
A23: In/Out VI
2005272 page 1, 2
A
Related ND-1021042 Figures: 4-120, 4-153C, 4-172, 4-175, 4-178, 4-186, 4-189, 4-190
See also: transcription of drawing to CAD or images rendered from CAD
A24: In/Out VII
2005273 page 1, 2
A
Related ND-1021042 Figures: 4-120, 4-122, 4-124, 4-135, 4-153B, 4-159, 4-165, 4-166, 4-171, 4-175, 4-178, 4-190
See also: transcription of drawing to CAD or images rendered from CAD
A25 - A26: Interface
2005928
A
Related ND-1021042 Figures: 4-191, 4-218, 4-225, 4-227
A27 - A29: Interface
2005933 page 1, 2
n/a
We don't have drawing 2005933.  The next-most-recent version of the circuit that we have is the one from AGC p/n 2003200, namely drawing 2005912B (page 1, 2). In fact, Eldon Hall himself supplied that earlier version of the circuit rather than drawing 2005933, so presumably he believed it was up-to-date.

Related ND-1021042 Figures: 4-192
A30 - A31: Power Supply
2005971 page 1, 2
A
We don't have sheet #2 of this drawing, which (in analogy to drawing 2005916x) presumably contains tables of component part numbers and values.

Related ND-1021042 Figures: 4-219B, 4-220B
A52: Restart Monitor
2003305 B The drawing number and revision required are not actually known.  This is the only version of the restart-monitor circuit we're aware of.

See also: transcription of drawing to CAD or images rendered from CAD
B1 - B6: Rope Memory
2005012B page 1, 2 B
Eldon Hall didn't supply drawings for modules B1-B6, so we have simply used the latest revision of the drawing that we have.

Note that this is a J-size (96"×34") drawing, with somewhat smaller text than other drawings, so this may affect choice of paper sizes for making physical printouts.

Related ND-1021042 Figures: 4-210, 4-211, 4-212, 4-213, 4-214
See also: transcription of drawing to CAD or images rendered from CAD
B7: Oscillator
2005930 page 1, 2, 3

Related ND-1021042 Figures: 4-118
B8: Alarms
2005975

Related ND-1021042 Figures: 4-221
B9 - B10: Erasable Drivers
2005934

Related ND-1021042 Figures: 4-202
B11: Current Switch
2005925

Related ND-1021042 Figures: 4-202
B12: Erasable Memory
2005931

Related ND-1021042 Figures: 4-205
B13: Sense Amplifier
2005970

Related ND-1021042 Figures: 4-204, 4-205
B14: Sense Amplifier
2005969

Related ND-1021042 Figures: 4-215, 4-216
B15: Strand Select
2005926

Related ND-1021042 Figures: 4-210, 4-215
B16 - B17: Rope Driver
2005938

Related ND-1021042 Figures: 4-211, 4-212, 4-213, 4-214
Dual NOR Gate 2005011- page 1, 2 -
Drawing 2005011 does not represent circuitry that actually appears explicitly within the AGC or DSKY.  Rather, it is MIT/IL's helpful explanation of the internal structure of the dual-NOR-gate integrated circuits that are used in a number of the AGC circuits.

Drawings for LM/Block II DSKY

Drawings for LM/Block II DSKY p/n 2003985-051

Module Description
Drawing Number
Comments
DSKY Interconnection Drawing
2005951B page 1, 2

D1 - D6: Indicator Driver
2005952-
See also: transcription of drawing to CAD or images rendered from CAD
D7: Power Supply Module
2005904C
See also: transcription of drawing to CAD or images rendered from CAD
D8: Keyboard Module
2005903A
See also: transcription of drawing to CAD or images rendered from CAD
AGC DSKY Signal Flow Diagram
2005950C page 1, 2

Drawings for LM/Block II DSKY p/n 2003950-011

Module Description
Drawing Number
Comments
DSKY Interconnection Drawing
2005953B page 1, 2

D1 - D6: Indicator Driver
2005952-
See also: transcription of drawing to CAD or images rendered from CAD
D7: Power Supply Module
2005921-
See also: transcription of drawing to CAD or images rendered from CAD
D8: Keyboard Module
2005903A
See also: transcription of drawing to CAD or images rendered from CAD
AGC DSKY Signal Flow Diagram
2005918- page 1, 2

Drawings for LM/Block II DSKY p/n 2003994

Module Description
Drawing Number
Comments
DSKY Interconnection Drawing
2005954

D1 - D6: Indicator Driver
2005973
We currently have no original drawings for circuit 2005973.  The CAD files and associated image linked in the CAD columns to the left is a reconstructed form of 2005973.  It was created by taking the drawing of an earlier version of the DSKY indicator-driver circuit (namely 2005952-) and modifying it using the indicator-driver circuit from ND-1021042  (which is believed to be the same circuitry as 2005973 but re-drafted by AC Electronics to fit onto the pages of their document). The reconstruction may be imperfect, but it's the best that we currently have.

Related ND-1021042 Figures: 4-225, 4-226, 4-227, 4-229, 4-230, 4-231
See also: transcription of 2005952 + ND-1021042 to CAD or images rendered from CAD
D7: Power Supply Module
2005937
Similarly to drawing 2005973 above, the CAD files and associated image been reconstructed from an earlier version of the power-supply module circuit (2005921-) and from ND-1021042, since no surviving copy of 2005937 is known.  I feel pretty confident with this reconstruction, because all known drawings of earlier versions of this circuit (2005904B, 2005904C, and 2005921-) differ by only a few resistor and capacitor values.  Specifically, the only resistor and capacitor values that could differ between the real 2005937 drawing and the reconstructed drawing (namely, R1, R2, and C1) are not specified by design anyway, but rather were chosen after electrical testing from tables of possible substitutions within the drawing itself.  It is possible for the substitution tables in the reconstructed drawing to be incomplete, but I don't think the tables could actually be wrong in the sense of containing wrong values.

Now, admittedly, the drawing in ND-1021042 is from rev F of that document, whereas the 2003993 AGC and 2003994 DSKY were first introduced in rev H of the document.  So you could interpret that as meaning that the drawing in ND-1021042 was not current and related to an earlier version of the DSKY.  Or, you could equally well interpret it as meaning that the circuit diagram hadn't changed in the 2003994 DSKY.  The difference between the interpretations is in your confidence level of how well AC Electronics was doing it's job of documenting the circuitry, and you can draw your own conclusions on the matter.

Related ND-1021042 Figures: 4-232
See also: transcription of 2005921- + ND-1021042 to CAD or images rendered from CAD
D8: Keyboard Module
2005939
Instead, see drawing 2005903A, used in DSKY p/n's 2003985 and 2003950.  The circuitry in drawing 2005903A is identical to the circuitry shown in AC Electronics document ND-1021042 for DSKY p/n 2003994, so presumably the differences between drawings 2005939 and 2005903A are either non-electrical or else there were part number changes for some of the electrical components.

As far as non-electrical changes are concerned, I don't think we really have any way to know.  As far as component changes are concerned, ECP 505 ("Implementation of flight processing spec ND-1002314 and new diode") has been pointed out to me.  Possibly all of the diodes were swapped out with a different diode.

Note, though, that the same rev F vs rev H problem in ND-1021042 occurs as for the power-supply module drawing 2005937 above, and just as for it, you'll need to draw your own conclusions.

Related ND-1021042 Figures: 4-224
See also: CAD of drawing 2005903A or images rendered from CAD


Appendix: Evolution of AGC/DSKY Part Numbers

The way different part numbers of AGCs or DSKYs are related to one another is that you start with a given assembly with a certain part number (such as Block II AGC with p/n 2003100-011), then you apply an Engineering Change Proposal, or ECP for short, such as ECP 322 (described as "computer wiring changes"), with the result that you now have a different assembly p/n 2003100-021. 

Evolution of Block II AGC Part Numbers

The list below shows how all known Block II AGC part numbers are interrelated according to the principle just mentioned.  Many of these changes clearly are not electrical in nature, or else refer to intermediate or test versions of the AGC, so to simplify it a little bit I've highlighted in red the path (I think) from the earliest Block II AGC to the AGC p/n(s) used in flown missions.  (Sometimes there are multiple paths to get to the same part number, if the ECPs are applied in different orders.  For example, p/n 2003993-061 + ECP 815 = p/n 2003993-071 + ECP 719 = p/n 2003993-111.  I've only bothered to show one such path below in the few cases where that happens.)

Note that there is also an ECP 483 for p/n 203993 listed in Table 8-II of document ND-1021042 (from which the information above came), but I haven't been able so far to find out what it is, nor at what dash number of 2003993 it became effective.  In earlier section providing drawings for 2003993-111, I arbitrarily assumed that ECP 483 had been applied.

Evolution of Block II DSKY Part Numbers

TBD.

Evolution of Block I AGC Part Numbers

TBD.

Evolution of Block I DSKY Part Numbers

TBD.

Appendix: AGC and DSKY Part Numbers vs Serial Number

Note that the table that follows isn't guaranteed to be perfect, but simply reflect the limits of the presently-available documentation.  It's not really needed for anything, but it's just kind of fun to see what AGC/DSKY part numbers were used in actual practice.  The information came from several sources, two of which (a memo titled "SKYLOTS (Skylab B Optical Telescope System)" and a note titled "Where and What are the Computers") have not yet reached our document library, and so I cannot link them for you yet. There are a couple of places where the sources conflict, in which case both sets of information are included.  I think I may also have mixed up IL part numbers and Raytheon part numbers for the AGC, so there's another source of confusion.

Serial
Number
Block I Part Numbers and Dispositions
Block 2 Part Numbers and Dispositions
AGC
Main DSKY
Nav DSKY
AGC
DSKY
1
Mission AS-202
CSM-011
p/n TBD
Mission AS-202
CSM-011
p/n TBD
Mission AS-202
CSM-011
p/n TBD


2

Apollo 4
CMO-17
p/n TBD



3

Qual 111 G&N System
p/n TBD



4
Qual 110 Subsystem
p/n TBD




5


Qual 111 G&N System
p/n TBD


6



p/n 2003100-021
(p/n from drawing 2003101C
in AGC Handbook)

7

Qual 110 Subsystem
p/n TBD
Apollo 6
CMO-20
p/n TBD
p/n 2003100-021
(p/n from drawing 6003001D
in AGC Handbook)

8
Qual 111 G&N System
p/n TBD

Qual 110 Subsystem
p/n TBD
p/n 2003100-021
(p/n from drawing 6003001D
in AGC Handbook)
p/n 2003985-051
(p/n from drawing 6003001D
in AGC Handbook)
9

Apollo 6
CMO-20
p/n TBD

p/n 2003100-021
(p/n from drawing 6003001D
in AGC Handbook)

10


Mission AS-202
CMO-17
p/n TBD


11




p/n 2003985-051
(p/n from drawing 2003101C
in AGC Handbook)
12




p/n 2003985-051
(p/n from drawing 2003101C
in AGC Handbook)
13
Apollo 6
CMO-20
p/n TBD



p/n 2003985-051
(p/n from drawing 6003001D
in AGC Handbook)
14
Apollo 4
CMO-17
p/n TBD




15





16



Block II/LM
G&N 203/604
Qualification System
p/n 2003993-TBD

17





18



(Shipped to Raytheon)
p/n 2003993-TBD
p/n 2003985-051
(p/n from drawing 6003001D
in AGC Handbook)
19



(Shipped to MSC)
p/n 2003993-TBD

20



(Shipped to Raytheon)
p/n 2003993-TBD

21





22



(Shipped to MSC)
p/n 2003993-TBD

23



(Shipped to Raytheon)
p/n 2003993-041

24



Apollo 17 LM
p/n 2003993-TBD

25



Apollo 12 LM
p/n 2003993-TBD

26



p/n 2003993-021 -091
(p/n from Table II here)

27



Apollo 7 CM
p/n 2003993-111

28



G&N 612
LM-15
p/n 2003993-071

29



Apollo 15 LM
p/n 2003993-091 -111

30



Apollo 5 LM
p/n 2003993-011
(p/n from Table IV here)
Block II/LM
G&N 203/604
Qualification System
p/n 2003994-TBD
31



Apollo 10 LM
p/n 2003993-TBD

32



Apollo 9 LM
p/n 2003993-031
(p/n from Table II here)

33



Apollo 14 LM
p/n 2003993-071

34



Apollo 12 CM
p/n 2003993-TBD
KSC Simulator
p/n 2003994-TBD
35



p/n 2003993-111 (Shipped to Delco)
p/n 2003994-TBD
36



p/n 2003993-111 p/n 2003994-TBD
37



Apollo 9 CM
p/n 2003993-TBD
Apollo 5 LM
p/n 2003994-011
(p/n from Table IV here)
38



p/n 2003993-051 -111
(Shipped to MSC)
p/n 2003994-TBD
39



p/n 2003993-081 MIT Simulator
p/n 2003994-TBD
40



Apollo 10 CM
p/n 2003993-TBD
p/n 2003994-091
41



Apollo 16 CM
p/n 2003993-071
p/n 2003994-091
42



Apollo 11 LM
p/n 2003993-TBD
Apollo 9 CM (Nav)
p/n 2003994-TBD
43



Apollo 16 LM
p/n 2003993-111
Apollo 10 CM (Main)
p/n 2003994-TBD
44



Apollo 11 CM
p/n 2003993-TBD
p/n 2003994-121
45



Apollo 14 CM
p/n 2003993-111
p/n 2003994-051
46



Apollo 13 LM
p/n 2003993-TBD
GAC Simulator
p/n 2003994-011
(p/n from Table II here)
47



p/n 2003993-061 p/n 2003994-051
48



p/n 2003993-051 Apollo 8 CM (Nav)
p/n 2003994-TBD
49




p/n 2003994-011 -021
(p/n from Table II here)
50



Apollo 15 CM
p/n 2003993-061
Apollo 7 CM (Main)
p/n 2003994-TBD
51



p/n 2003993-061 Apollo 9 LM
p/n 2003994-TBD
52



p/n 2003993-051 p/n 2003994-021
53



Apollo 13 CM
p/n 2003993-TBD
Apollo 11 CM (Main)
p/n 2003994-TBD
54



p/n 2003993-TBD Apollo 11 LM
p/n 2003994-TBD
55



p/n 2003993-061 p/n 2003994-021
56



Apollo 17 CM
p/n 2003993-061
Apollo 12 LM
p/n 2003994-TBD
57



p/n 2003993-TBD
58



p/n 2003993-061 Apollo 8 CM (Main)
p/n 2003994-TBD
59



p/n 2003993-091 Apollo 9 CM (Main)
p/n 2003994-TBD
60




p/n 2003994-021
61




Apollo 13 LM
p/n 2003994-TBD
62




Apollo 10 CM (Nav)
p/n 2003994-TBD
63




Apollo 14 LM
p/n 2003994-TBD
64




Apollo 7 CM (Nav)
p/n 2003994-TBD
65




Apollo 10 LM
p/n 2003994-TBD
66




Apollo 11 CM (Nav)
p/n 2003994-TBD
67




Apollo 12 CM (Main)
p/n 2003994-TBD
68




p/n 2003994-091
69




Apollo 14 CM (Nav)
p/n 2003994-TBD
70




p/n 2003994-121
71




p/n 2003994-091
72




Apollo 13 CM (Main)
p/n 2003994-TBD
73




p/n 2003994-121
74




Apollo 12 CM (Nav)
p/n 2003994-TBD
75




Apollo 15 CM (Nav?)
p/n 2003994-121
76




p/n 2003994-121
77




Apollo 14 CM (Main)
p/n 2003994-TBD
78




Apollo 16 LM
p/n 2003994-TBD
79




Apollo 13 CM (Nav)
p/n 2003994-TBD
80




p/n 2003994-TBD
81




p/n 2003994-091
82




p/n 2003994-121
83




Apollo 16 CM (Nav)
p/n 2003994-121
84




p/n 2003994-121
85




Apollo 17 LM
p/n 2003994-TBD
86




p/n 2003994-121
87




p/n 2003994-091
88




p/n 2003994-051
89




p/n 2003994-121
90




Apollo 16 CM (Main)
p/n 2003994-121
91




p/n 2003994-121
92




p/n 2003994-121
93




p/n 2003994-121
94




Apollo 15 CM (Main?)
p/n 2003994-121
95




p/n 2003994-121
96




Apollo 15 LM
p/n 2003994-TBD
97




p/n 2003994-121
98




p/n 2003994-121
99




Apollo 17 CM
p/n 2003994-121
100




Apollo 17 CM
p/n 2003994-121
101




p/n 2003994-121

Appendix: All Available MIT/IL Apollo Engineering Drawings

At this spot, I used to have indexes into our entire collection of MIT/IL Apollo engineering drawings (i.e., electrical schematics and mechanical drawings).  But the index became so huge that it threatened to swamp all of the other content on this page!  Hence, I've moved the engineering-drawing index to its own separate page, where it can grow to its heart's content.

Electronics Component Part Numbers and their SCDs

We don't have an official document, in so far as I am aware, giving the Instrumentation Lab's part numbers for electronics components like resistors, capacitors, transistors, and so on.  Many of them are deducible from other documents, like the AGC Handbook drawings.  For example, from drawing 2005952-, we can find out that part number 1006750-32 is a 1/4W 1K resistor with a 2% tolerance, while part number 1010406-7 is an 8.2 μH 10% tolerance R.F. coil.  Mike Stewart (thanks, Mike!) has done a lot of that for us, but the task is still incomplete.


The list above may not be fully up-to-date with respect to the master list, which is actually in our GitHub repository.  If you have corrections or additions to this table, I believe you can edit the table directly in GitHub, though your changes won't go live unless we approve them.

In addition to the raw list of part numbers above, we have the Specification Control Drawings (SCDs) for most of them.  In modern terms you can think of the SCD as being like the data sheets for the components, except that instead of being written by the manufacturers, they are Instrumentation Lab drawings, and serve roughly the same purpose.  We have most of the SCDs in multiple revisions, so if you're interested in that kind of thing, you can see how the specifications evolved over time.  If you want to see them, look on our AGC engineering-drawing index page.

Appendix: Signal Wiring Diagrams for the Block II AGC 2003100 and the NOR-Gate Problem

First, an elementary introductory digression, for anyone who isn't an electronics expert but has persevered in reading to this point.

When designing electronic circuitry, it is customary to assign each electrical component in the circuit a unique "reference designator" (or "refd", pronounced REF-DEE, for short), and to refer to the components by those refd's.  The refd's can be anything, but customarily they consist of a letter to indicate the general type of component — R for resistors, C for capacitors, D (or perhaps CR) for diodes, and so on — followed by a number to indicate which specific component it is within the circuit.  For example, in the typical kind of circuit diagram shown to the right, you see resistors R1 through R7, capacitor C3, transistors Q1 through Q3, and so on.

Integrated circuits (IC's) typically have U as the alphabetical prefix, thus you might have integrated circuits U1, U2, U3, etc.

One thing that happens sometimes is that a given component might actually be a conveniently packaged-together collection of several essentially interchangeable simpler parts.  For example, a "dual NOR gate" integrated circuit would be a device that provides two separate NOR gates, which are independent of each other but are packaged together to save space or cost or for some other reason of convenience.  When that happens, the overall integrated circuit still has a U-based refd, perhaps U3, but the two NOR-gates comprising it each have refd's of their own, which would normally be U3A and U3B.

The example of a NOR-gate wasn't chosen arbitrarily. In fact, since integrated circuits were a pretty new development during the early Apollo Program, and were still suspiciously unreliable and quite expensive, the AGC circuitry originally didn't use any of them.  Eventually, though, the relentless pressure to miniaturize forced integrated circuits into the design.  As it happens, the AGC ended up using a single type of integrated circuit (the DSKY used none at all), though it used lots of them.  As you've probably guessed, that one type of IC was in fact a dual triple-input NOR gate.

(Actually, that's a bit of an over-simplification, though it's largely true for our purposes.  In fact, the Block II AGC used dual NOR gate integrated circuits, as stated, but the Block I AGC used integrated circuits containing a single NOR-gate each.  Besides that, the sense amplifier modules used comparatively small numbers of sense-amplifier integrated circuits, whose internal composition is depicted in the figure to the right.  The sense amplifier integrated circuit was exactly as complex as a dual triple-input NOR gate integrated IC, in that each of them contained 6 NPN transistors and 8 resistors ... which is just an interesting factoid and is neither here nor there.  For the purposes of our present discussion, neither the Block I NOR gates nor the sense-amplifier ICs are of any relevance whatever.)

I won't bore you by telling you about the general properties of NOR gates, but to understand the discussion in this section you do need to know a couple of different things about them.  Firstly, in the AGC schematics a NOR gate is symbolized either as



and secondly, all of the three inputs of a NOR gate are interchangeable, in the sense that if you swapped any two of them, the behavior of the device would remain the same. (I suppose it may also be worth noting that of the two NOR-gate representations above, you can have two of the left-hand kind as the A and B parts of a dual NOR gate, or two of the right-hand kind, but not one of each.)

What this is all leading up to is that some of the early AGC (p/n 2003100 only) electrical schematic drawings:
  1. Do not list any ref's for NOR-gates, so we have no way of knowing from the schematics which individual NOR gate is packaged with any other into a dual-NOR IC; and
  2. Do not list any pin numbers for the NOR-gate inputs, so we have know way of knowing which of the interchangeable inputs any given input signal is hooked up to.

To get a sense of this, to the right there are two versions of a sample (nonsense) circuit consisting of NOR gates, one with refd's and pin numbers, and one without.  In the right-hand version, we know, for example, that pin U1A-J is connected to pins U1B-F, U2A-F, and U2B-F.  In the left-hand version we know that the output from one NOR gate is connected to some input or other on each of the other NOR gates.  Imagine trying to repair or discuss the left-hand version!

As far as the operation of the circuit is concerned, of course, it makes no difference at all whether or not those refd's or pin numbers are there, because all of the NOR gates are interchangeable and all of the inputs to them are interchangeable, so the OUTPUT we get from any given INPUT is still exactly the same.

In the same way, you personally may not care one way or the other which specific NOR gate is used for any given purpose in the AGC circuitry, nor may you care which input pin is which on those NOR gates.  If that's so, you don't need to read any further ... just go back to looking at the schematics presented above on this page and enjoy!

But the truth is that the original AGC developers did care which NOR gate was which and what pin number was what ... it's just that for some reason they didn't find it convenient to put that information directly into some of the schematic diagrams for AGC p/n 2003100, and hence they chose to provide it through some other mechanism.  That mechanism is the so-called "signal wiring diagram", and each of the schematic drawings in the AGC 2003100 containing NOR gates had an associated signal wiring diagram.  Below, there's a "typical" (actually, slightly more legible than usual) portion of a signal wiring diagram:

You may be forgiven for thinking that this makes the situation even more confusing to deal with, particularly since you are quite correct about it, but it helps if you know how to read it!  When you know how to read it, it tells you which NOR-gates are paired into which in the dual NOR-gate IC's, which of the pair is the "A" member of the duet and which is the "B" member, and which pin numbers the signals are hooked up to.

It doesn't tell you exactly how to specify the refd's of the dual-NOR IC's, but we know from other versions of the AGC roughly how they did that, so we'll talk about that later.

The first thing to notice is that one side of the diagram is marked as LEFT and the other as RIGHT.  In this drawing, LEFT is at the bottom and RIGHT is at the top, but in other drawings that's reversed, so try to think only of LEFT and RIGHT instead of bottom and top.

Next, notice the little numbers written along the LEFT or bottom edge (39155, 39145, 39149, ...) and RIGHT or top edge (39156, 19151, 39152, ...).  Those numbers are actually written on the NOR gates in the schematics, in lieu of refd's, and each individual NOR gate is identified uniquely by these numbers.  These are called "gate numbers".  So, a pair of such gate numbers could uniquely specify a dual-NOR gate.  The RIGHT numbers are the "A" NOR gates, and the numbers opposite them on the LEFT are the associated "B" NOR gates within the same dual NOR IC. 

Before talking about the other stuff written on the diagram, let's talk a little more about the dual-NOR ICs.  The AGC's were 10-pin rectangular packages, with the pins on them variously labeled either numerically or alphabetically, depending on the purpose of the discussion.  We might draw it like so, with the "A" NOR gate on the left and the "B" NOR gate on the right:


Ignore the fact that the NOR gates now look like little rocket ships; that may or may not be significant.  Rather, the important things to note are that there are VCC and GND inputs to power the device, that the "A" gate has pins 1-4 (or J, A, B, C), and that the "B" gate has pins 6-9 (or D, E, F, K).

If you look along the bottom (LEFT) edge of the signal wiring diagram, you'll see a repeating pattern (from left to right) consisting of

  1. a small square
  2. an even smaller circle
  3. 3 empty spots
  4. an oval with a number inside
What those represent in terms of the dual-NOR IC are:
  1. pin 10 of the dual-NOR
  2. pin 9
  3. pins 8, 7, and 6
  4. a spot unrelated to the NOR
Similarly, along the top (RIGHT) edge of the signal wiring diagram, you'll see a similar but slightly less regular pattern of 6 positions:
  1. small circle
  2. 3 empty spots
  3. 2 spots with several possible markings
And in terms of the dual-NORs, these are:
  1. pin 1 of the dual-NOR
  2. pins 2, 3, and 4
  3. 2 other things not related to the NOR.
We'll get to what those non-NOR things are later, but the point to understand right now is that 9 of each dual-NOR's 10 pins appear in a regular manner along these edges.  (The 10th pin is always grounded, and we won't worry ourselves about it.)

What about those weird, snake-like horizontal lines running lengthwise along the middle of the signal wiring diagram?  Wires!  Where the wire points downward, there's a connection along the bottom edge of the diagram, whereas when it points upward there's a connection along the top edge of the diagram.  In the image below, I've added some false coloring to just one of those snakelike lines to focus the attention on it:

So according to the description I just gave, the wire makes a connection to the following:

Now, if you know anything about electronics, you may be worried that the outputs of two different NOR gates are tied together.  Don't worry, though, these NOR-gates have open-collector outputs (or more precisely, open-collector with a pullup resistor to VCC), and so they can be tied together to increase their drive capacity (or to effectively increase the number of NOR inputs for a single output) without any problem.

Perhaps I should finally say what some of these non-NOR markings along the edges are:

At any rate, the point is that this red wire represents two NOR-gates tied together to drive connector pin 111.  Now, I didn't mention it before, but this signal wiring diagram happens to be from sheet 1 of drawing 2005061D, and if we look at that drawing, we will indeed find that connector pin 111 is being driven by NOR gates 39107 and 39155.

What is this "inter-quadrant" thing of which I spoke, and for that matter, what is a "quadrant" anyway?

For these AGC modules, the connector from the module to the AGC backplane has 4 rows of 69 pins each (numbered 1 to 71, but with 21 and 51 missing).  Each one of those rows of pins essentially has its own circuit associated with it, and these separate circuits are called "quadrants".  The concept of the "quadrant" was used only for early dash numbers of the 2003100 AGC (such as the one we have schematics for!), and disappeared for later 2003100 versions, and for the 2003200 and 2003993 AGC's, though much of the numbering of components on the schematics remains tied to the quadrant concept even if the quadrants themselves disappeared.

By "separate circuits", I mean logically separate rather than physically separated onto different circuit boards, though apparently that was originally what was tried.  And usually, the circuitry on the quadrants isn't entirely logically independent of the circuitry on the other quadrants, and in that case there have to be one or more electrical connections between the quadrants of the module ... i.e., inter-quadrant connections.

In fact, the signal wiring diagram I've been showing you isn't the complete diagram for drawing 2005061D, but simply the signal wiring diagram for quadrant 1 of 2005061D.  There are three other quadrants, and therefore 3 other signal wiring diagrams for this module as well.  Most modules have a complete complement of 4 quadrants, and thus have 4 signal wiring diagrams associated with them.  But some module have less quadrants and therefore less signal wiring diagrams.

So now all of the questions are answered except for refd's.  For that, I want to direct your attention just above the row of gate numbers at the bottom edge of the signal wiring diagram shown above, or just below the row of gate numbers along the top edge.  You'll see a row of tiny, tiny numbers going from 1 (at the left) to 180 (at the right) there.  Or more accurately, you'll see rows of tiny smudges that may or may not be numbers, but you can still see that there are 180 of them.  Let's call these things "smudge numbers", for lack of a better term.  The IC's are numbered sequentially, starting at the end with the larger smudge numbers, where we find U01, and moving toward the end with the smaller smudge numbers, where we find U30.

Actually, there's some subtlety involve here.  For example, what happens if there's an open space, as there is in our pictured signal wiring diagram at U23?  Should we just skip U23 in our numbering altogether, or should the next position become U23 rather than U24?  You could argue it either way, but I'd vote for skipping U23 altogether, because it helps preserve IC numbering across different hardware versions.  In other words, if a dual-NOR is removed or added, it won't necessarily cause all of the refd's for the other dual-NORs to change.

Another subtlety in the IC numbering is the quadrants:  The entire circuit module consists of 4 quadrants, and if we followed the scheme just described, there would be 4 IC's labeled U01, 4 labeled U02, and so on.  Not good!  So in our CAD work we actually prefix the quadrant numbers to the IC numbering.  In other words, in quadrant 1, the IC's run from U101 up to U130; in quadrant 2, the IC's run from U201 up to U230; etc.  Thus every IC ends up with a unique number within the module, and we can still use that number to precisely identify where it is located physically.

And finally, one last subtlety:  Some of the quadrants have signal wiring diagrams as shown, with LEFT on the bottom, RIGHT on the top, and smudge numbers increasing from left to right.  Other quadrants are reversed, with LEFT on the bottom, RIGHT on the top, and smudge numbers increasing from right to left.  My descriptions above are all still correct, as long as you keep thinking of LEFT and RIGHT and ordering of smudge numbers as I've urged, rather than thinking of the top, bottom, right, and left edges of the signal wiring diagram as you might otherwise be inclined to do.  The reason for this reversal seems to have to do with some of the quadrants being on the front side, and some being on the back side, with the numbering consequently mirror imaged.

Appendix: Signal Wiring Diagrams and the Block I AGC 1003700

For the Block I AGC, problems similar to those described in the preceding section exist, though the problems and solutions are different in detail.  In fact, read the preceding section before reading this one!

One problem that can thankfully be ignored in the Block I AGC is that the NOR-gate integrated circuit contains a single triple-input NOR gate, packaged in a TO-47 can, rather than two independent NOR gates packaged together in a flatpack, as in the Block II AGC.  That simplifies a lot.  You can see both a photo of such a gate (to the left) and a diagram elucidating its pinout and internal circuit (to the right).

A problem the Block I "logic flow diagrams" (schematics containing NOR gates) have that the Block II doesn't have, is that there were apparently multiple hardware generations of the Block I AGC that were mechanically quite different.  In particular, both the backplane-connector pin numbers and the means for identifying the NOR-gate components differed from one hardware generation to the next.  The schematic diagrams, meanwhile, showed the connector pin numbers and gate identification for multiple hardware generations, thus making them a tad more confusing than they might have been otherwise.

We don't actually know much about these different hardware generations, but here's our current thinking on the subject.  We think there were three separate Block I AGC hardware generations, which may have differed as follows:

For example, in the tiny excerpt from one of the Block I electrical schematics to the left, consider the NOR gate with the markings "2G5" and "65129".  "2G5" was how the gate was identified in generation "AGC 4", while "65129" was how it was identified in generation "AGC 5", according to the notes (not shown) written in the schematic itself. 

Similarly, consider the connector pin for the backplane signal "MPO".  It is marked both as pin #94 and as pin #104. The former is for AGC 4, while the latter is for AGC 5.

However, the Block I AGC schematics have the same characteristics as the early Block II schematics, in the sense that they do not display pin numbers for the (interchangeable) inputs of the NOR gates, nor do they indicate what we would think of as reference designators for the NOR gates.  Plus, each of the NOR gates in the example to the left has a single input ... but from the figure above, we know that pins 1, 3, and 5 of the NOR gate were all interchangeable, so which input is the one being used?  They probably are not all the "middle" pin, pin #3, since that wouldn't always have been the pin it was most convenient to physically route a wire to. 

At any rate, since the schematic doesn't have this kind of info in it, the information has to come from somewhere else.  It must instead be deduced instead from the so-called "signal wiring diagrams".

TBD



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Last modified by Ronald Burkey on 2018-12-07.

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