Apollo Guidance Computer - facts from the horses mouths

A few weeks ago there was a thread where ppl were citing 'facts' about design and implementation issues of the AGC. I had forgotten about this site....it should clear up some misunderstandings/flat out wrong assertions about the AGC.
https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/conference3/intro.htm

Some years ago I started doing a FPGA implementation of the AGC ALU. That had its share of challenges, mainly neither the architecture nor logic diagrams were available. I was trying to make a 'work alike' based on Frank O'Brien's book. Some time later, block two schematics were published.
http://klabs.org/history/ech/agc_schematics/

Yes, the only IC used was a 3 input NOR gate. The effort got kicked of in 1963 and Fairchild Semiconductor was only 5 years old. Interesting - risking a project on a technology in which understanding of fabrication, impurities, bonding, etc. were just beginning.

I also recently came across this site - Apparently I wasn't the only one who had the idea...

https://www.ibiblio.org/apollo/Pultorak.html
Happy reading.
J

 

[Jan Panteltje]

On a sunny day (Wed, 24 Jul 2019 19:13:05 -0700 (PDT)) it happened
jjhudak4@gmail.com wrote in
<7ee0bec8-b96f-45ff-b41f-daa012c1488f@googlegroups.com>:

A few weeks ago there was a thread where ppl were citing 'facts' about design
and implementation issues of the AGC. I had forgotten about this site...it
should clear up some misunderstandings/flat out wrong assertions about the
AGC.
https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/conference3/intro.htm

Some
years ago I started doing a FPGA implementation of the AGC ALU. That had
its share of challenges, mainly neither the architecture nor logic diagrams
were available. I was trying to make a 'work alike' based on Frank O'Brien's
book. Some time later, block two schematics were published.
http://klabs.org/history/ech/agc_schematics/

Very nice..
All Ye Need is transistors.
And do everything with NOR gates.



I like the power supply too
That sort of circuit was very common in those days.

Yes, the only IC used was a 3 input NOR gate. The effort got kicked of in 1963
and Fairchild Semiconductor was only 5 years old. Interesting - risking
a project on a technology in which understanding of fabrication, impurities,
bonding, etc. were just beginning.

I also recently came across this site - Apparently I wasn't the only one who
had the idea...

https://www.ibiblio.org/apollo/Pultorak.html

yes or one Microchip PIC.
Not sure how that would behave in radiation.


>Happy reading.

 

[bitrex]

On 7/25/19 2:19 AM, Jan Panteltje wrote:

On a sunny day (Wed, 24 Jul 2019 19:13:05 -0700 (PDT)) it happened
jjhudak4@gmail.com wrote in
7ee0bec8-b96f-45ff-b41f-daa012c1488f@googlegroups.com>:

A few weeks ago there was a thread where ppl were citing 'facts' about design
and implementation issues of the AGC. I had forgotten about this site...it
should clear up some misunderstandings/flat out wrong assertions about the
AGC.
https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/conference3/intro.htm

Some
years ago I started doing a FPGA implementation of the AGC ALU. That had
its share of challenges, mainly neither the architecture nor logic diagrams
were available. I was trying to make a 'work alike' based on Frank O'Brien's
book. Some time later, block two schematics were published.
http://klabs.org/history/ech/agc_schematics/

Very nice..
All Ye Need is transistors.
And do everything with NOR gates.



I like the power supply too
That sort of circuit was very common in those days.


Yes, the only IC used was a 3 input NOR gate. The effort got kicked of in 1963
and Fairchild Semiconductor was only 5 years old. Interesting - risking
a project on a technology in which understanding of fabrication, impurities,
bonding, etc. were just beginning.

I also recently came across this site - Apparently I wasn't the only one who
had the idea...

https://www.ibiblio.org/apollo/Pultorak.html

yes or one Microchip PIC.
Not sure how that would behave in radiation.


Happy reading.

a AGC emulator for an 8 bit RISC seems plausible, usually Flash memory
at least is read word-wise and the Apollo AGC has a 16 bit word length.

A e.g. PDP-8 emulator is more problematic there isn't any both time and
space-efficient way I know of to pack a 12 bit word into 16 bits and
read/write it from 16 bit/8 bit memory blocks.

 

[Jan Panteltje]

On a sunny day (Thu, 25 Jul 2019 16:53:47 +0300) it happened
upsidedown@downunder.com wrote in
<4qcjjetoq8lmb5fsg2haqananfcct8khc8@4ax.com>:

On Thu, 25 Jul 2019 06:19:21 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Wed, 24 Jul 2019 19:13:05 -0700 (PDT)) it happened
jjhudak4@gmail.com wrote in
7ee0bec8-b96f-45ff-b41f-daa012c1488f@googlegroups.com>:

A few weeks ago there was a thread where ppl were citing 'facts' about design
and implementation issues of the AGC. I had forgotten about this site...it
should clear up some misunderstandings/flat out wrong assertions about the
AGC.
https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/conference3/intro.htm

Some
years ago I started doing a FPGA implementation of the AGC ALU. That had
its share of challenges, mainly neither the architecture nor logic diagrams
were available. I was trying to make a 'work alike' based on Frank O'Brien's
book. Some time later, block two schematics were published.
http://klabs.org/history/ech/agc_schematics/

Very nice..
All Ye Need is transistors.
And do everything with NOR gates.



There are also pictures of RTL logic used in AGC at
https://en.wikipedia.org/wiki/Resistor%E2%80%93transistor_logic

Yes, funny I was thinking of that, because even in the sixties I designed and build
a triggered scope with RTL logic, so was wondering maybe those were not rad-hard enough...
Makes sense to use those, reduces part count considerably.

Next was DTL... have not done much with that.
TTL yes, and CMOS , ECL no..

 

On Thu, 25 Jul 2019 06:19:21 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Wed, 24 Jul 2019 19:13:05 -0700 (PDT)) it happened
jjhudak4@gmail.com wrote in
7ee0bec8-b96f-45ff-b41f-daa012c1488f@googlegroups.com>:

A few weeks ago there was a thread where ppl were citing 'facts' about design
and implementation issues of the AGC. I had forgotten about this site...it
should clear up some misunderstandings/flat out wrong assertions about the
AGC.
https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/conference3/intro.htm

Some
years ago I started doing a FPGA implementation of the AGC ALU. That had
its share of challenges, mainly neither the architecture nor logic diagrams
were available. I was trying to make a 'work alike' based on Frank O'Brien's
book. Some time later, block two schematics were published.
http://klabs.org/history/ech/agc_schematics/

Very nice..
All Ye Need is transistors.
And do everything with NOR gates.

There are also pictures of RTL logic used in AGC at
https://en.wikipedia.org/wiki/Resistor%E2%80%93transistor_logic

Similar RTL chips where also used by some Titan missiles. After the
cold war, when some Titan missiles were converted to satellite
launchers, they needed some RTL chips for replacement. They had some
problems finding such chips any longer

I like the power supply too
That sort of circuit was very common in those days.


Yes, the only IC used was a 3 input NOR gate. The effort got kicked of in 1963
and Fairchild Semiconductor was only 5 years old. Interesting - risking
a project on a technology in which understanding of fabrication, impurities,
bonding, etc. were just beginning.

I also recently came across this site - Apparently I wasn't the only one who
had the idea...

https://www.ibiblio.org/apollo/Pultorak.html

yes or one Microchip PIC.
Not sure how that would behave in radiation.


Happy reading.

 

[Rob]

jjhudak4@gmail.com <jjhudak4@gmail.com> wrote:

A few weeks ago there was a thread where ppl were citing 'facts' about design and implementation issues of the AGC. I had forgotten about this site...it should clear up some misunderstandings/flat out wrong assertions about the AGC.
https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/conference3/intro.htm

Some years ago I started doing a FPGA implementation of the AGC ALU. That had its share of challenges, mainly neither the architecture nor logic diagrams were available. I was trying to make a 'work alike' based on Frank O'Brien's book. Some time later, block two schematics were published.
http://klabs.org/history/ech/agc_schematics/

Yes, the only IC used was a 3 input NOR gate. The effort got kicked of in 1963 and Fairchild Semiconductor was only 5 years old. Interesting - risking a project on a technology in which understanding of fabrication, impurities, bonding, etc. were just beginning.

I also recently came across this site - Apparently I wasn't the only one who had the idea...

https://www.ibiblio.org/apollo/Pultorak.html
Happy reading.
J

The multipart series about restoring an original AGC to working condition
on YouTube (Curious Marc) mentions a gate-exact FPGA implementation multiple
times, so no doubt others have succeeded in that.

 

[Jon Elson]

On Wed, 24 Jul 2019 19:13:05 -0700, jjhudak4 wrote:

Yes, the only IC used was a 3 input NOR gate. The effort got kicked of
in 1963 and Fairchild Semiconductor was only 5 years old. Interesting -
risking a project on a technology in which understanding of fabrication,
impurities, bonding, etc. were just beginning.

I have a Honeywell Alert computer that was developed for the X-15 project.
Design was started about a year before the AGC, but finished a year
earlier, as it was a much simpler project, overall. It is a DTL 24-bit
computer built from, I think, about 5 basic chip designs. There was an
edge-triggered universal FF. It could do D, JK, T and RS styles.
it fits in a half-ATR box and draws 125 W (25 A @ 5 V). It still works,
as best as I can see. I got a memory box with it, but it is a wreck and
I have no docs on it. I have some docs on the Alert, as well an an
AMAZING 2-volume set about the development of the project.

Jon

 

[three_jeeps]

On Thursday, July 25, 2019 at 2:19:29 AM UTC-4, Jan Panteltje wrote:

On a sunny day (Wed, 24 Jul 2019 19:13:05 -0700 (PDT)) it happened
jjhudak4@gmail.com wrote in
7ee0bec8-b96f-45ff-b41f-daa012c1488f@googlegroups.com>:

A few weeks ago there was a thread where ppl were citing 'facts' about design
and implementation issues of the AGC. I had forgotten about this site...it
should clear up some misunderstandings/flat out wrong assertions about the
AGC.
https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/conference3/intro.htm

Some
years ago I started doing a FPGA implementation of the AGC ALU. That had
its share of challenges, mainly neither the architecture nor logic diagrams
were available. I was trying to make a 'work alike' based on Frank O'Brien's
book. Some time later, block two schematics were published.
http://klabs.org/history/ech/agc_schematics/

Very nice..
All Ye Need is transistors.
And do everything with NOR gates.



I like the power supply too
That sort of circuit was very common in those days.


Yes, the only IC used was a 3 input NOR gate. The effort got kicked of in 1963
and Fairchild Semiconductor was only 5 years old. Interesting - risking
a project on a technology in which understanding of fabrication, impurities,
bonding, etc. were just beginning.

I also recently came across this site - Apparently I wasn't the only one who
had the idea...

https://www.ibiblio.org/apollo/Pultorak.html

yes or one Microchip PIC.
Not sure how that would behave in radiation.


Happy reading.

Sure, you could write an emulator on just about any single-chip CPU - it has been done many times. I run simh (on a RPi) in parallel with my old iron PDP8E and PDP11/34, and my hybrid 11/34 fpga+simulator.

My thrust was to design/build a hardware gate-level engine (using VHDL to specify a 3-input nor gate which would most likely be in a LUT), and not just emulate (in software) the thing.
j

 

[Robert Baer]

upsidedown@downunder.com wrote:

On Thu, 25 Jul 2019 06:19:21 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Wed, 24 Jul 2019 19:13:05 -0700 (PDT)) it happened
jjhudak4@gmail.com wrote in
7ee0bec8-b96f-45ff-b41f-daa012c1488f@googlegroups.com>:

A few weeks ago there was a thread where ppl were citing 'facts' about design
and implementation issues of the AGC. I had forgotten about this site...it
should clear up some misunderstandings/flat out wrong assertions about the
AGC.
https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/conference3/intro.htm

Some
years ago I started doing a FPGA implementation of the AGC ALU. That had
its share of challenges, mainly neither the architecture nor logic diagrams
were available. I was trying to make a 'work alike' based on Frank O'Brien's
book. Some time later, block two schematics were published.
http://klabs.org/history/ech/agc_schematics/

Very nice..
All Ye Need is transistors.
And do everything with NOR gates.



There are also pictures of RTL logic used in AGC at
https://en.wikipedia.org/wiki/Resistor%E2%80%93transistor_logic

Similar RTL chips where also used by some Titan missiles. After the
cold war, when some Titan missiles were converted to satellite
launchers, they needed some RTL chips for replacement. They had some
problems finding such chips any longer


I like the power supply too
That sort of circuit was very common in those days.


Yes, the only IC used was a 3 input NOR gate. The effort got kicked of in 1963
and Fairchild Semiconductor was only 5 years old. Interesting - risking
a project on a technology in which understanding of fabrication, impurities,
bonding, etc. were just beginning.

I also recently came across this site - Apparently I wasn't the only one who
had the idea...

https://www.ibiblio.org/apollo/Pultorak.html

yes or one Microchip PIC.
Not sure how that would behave in radiation.


Happy reading.

As i vaguely remember,from speed testing of RTL, the rise time was
about 6nSec and the delay was about 7nSec.

 

[Jan Panteltje]

On a sunny day (Thu, 25 Jul 2019 21:52:55 -0800) it happened Robert Baer
<robertbaer@localnet.com> wrote in <qIv_E.132763$s53.123532@fx33.iad>:

upsidedown@downunder.com wrote:
On Thu, 25 Jul 2019 06:19:21 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Wed, 24 Jul 2019 19:13:05 -0700 (PDT)) it happened
jjhudak4@gmail.com wrote in
7ee0bec8-b96f-45ff-b41f-daa012c1488f@googlegroups.com>:

A few weeks ago there was a thread where ppl were citing 'facts' about design
and implementation issues of the AGC. I had forgotten about this site...it
should clear up some misunderstandings/flat out wrong assertions about the
AGC.
https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/conference3/intro.htm

Some
years ago I started doing a FPGA implementation of the AGC ALU. That had
its share of challenges, mainly neither the architecture nor logic diagrams
were available. I was trying to make a 'work alike' based on Frank O'Brien's
book. Some time later, block two schematics were published.
http://klabs.org/history/ech/agc_schematics/

Very nice..
All Ye Need is transistors.
And do everything with NOR gates.



There are also pictures of RTL logic used in AGC at
https://en.wikipedia.org/wiki/Resistor%E2%80%93transistor_logic

Similar RTL chips where also used by some Titan missiles. After the
cold war, when some Titan missiles were converted to satellite
launchers, they needed some RTL chips for replacement. They had some
problems finding such chips any longer


I like the power supply too
That sort of circuit was very common in those days.


Yes, the only IC used was a 3 input NOR gate. The effort got kicked of in 1963
and Fairchild Semiconductor was only 5 years old. Interesting - risking
a project on a technology in which understanding of fabrication, impurities,
bonding, etc. were just beginning.

I also recently came across this site - Apparently I wasn't the only one who
had the idea...

https://www.ibiblio.org/apollo/Pultorak.html

yes or one Microchip PIC.
Not sure how that would behave in radiation.


Happy reading.

As i vaguely remember,from speed testing of RTL, the rise time was
about 6nSec and the delay was about 7nSec.

hehe, I was thinking "AGC" normally means 'Automatic Gain Control'
and did a look up for what else it could stand for.

The wikipedia link about that AGC (the Apollo Guidance Computer one) I found
is very informative for an overview of what hey were doing,
the hardware and programming, with lots of pictures:
https://en.wikipedia.org/wiki/Apollo_Guidance_Computer

and indeed it was RTL (4100 chips),
and the second model even less it had 2800 RTL chips more integration.

What I do not see is the point (with all respect) of rebuilding it in FPGA or something,
apart from even the fact that you cannot do RTL in FPGA AFAIK
But to run the same software in a PIC makes sense (or on a PC).
I remember playing moon landing game on a Commodore PET2000 I think it was in the late seventies.
Very interesting in that wikipedia link is the 'PGNCS 1668' bug they encountered
and that takes you right to the current state of affairs with embedded programming.

Whatever way you look at Apollo, it was a master piece.

 

[piglet]

On 26/07/2019 7:38 am, Jan Panteltje wrote:

and indeed it was RTL (4100 chips),
and the second model even less it had 2800 RTL chips more integration.

Yes, I think that is right. The first AGC used ICs of a single NOR gate
(3 transistors) in a round metal can like TO-99. The second version used
ICs with dual NOR gates (6 transistors) in ceramic flat packs. So fewer
chips but more gates in total

piglet

 

[Phil Hobbs]

On 7/26/19 2:38 AM, Jan Panteltje wrote:

On a sunny day (Thu, 25 Jul 2019 21:52:55 -0800) it happened Robert Baer
robertbaer@localnet.com> wrote in <qIv_E.132763$s53.123532@fx33.iad>:

upsidedown@downunder.com wrote:
On Thu, 25 Jul 2019 06:19:21 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Wed, 24 Jul 2019 19:13:05 -0700 (PDT)) it happened
jjhudak4@gmail.com wrote in
7ee0bec8-b96f-45ff-b41f-daa012c1488f@googlegroups.com>:

A few weeks ago there was a thread where ppl were citing 'facts' about design
and implementation issues of the AGC. I had forgotten about this site...it
should clear up some misunderstandings/flat out wrong assertions about the
AGC.
https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/conference3/intro.htm

Some
years ago I started doing a FPGA implementation of the AGC ALU. That had
its share of challenges, mainly neither the architecture nor logic diagrams
were available. I was trying to make a 'work alike' based on Frank O'Brien's
book. Some time later, block two schematics were published.
http://klabs.org/history/ech/agc_schematics/

Very nice..
All Ye Need is transistors.
And do everything with NOR gates.



There are also pictures of RTL logic used in AGC at
https://en.wikipedia.org/wiki/Resistor%E2%80%93transistor_logic

Similar RTL chips where also used by some Titan missiles. After the
cold war, when some Titan missiles were converted to satellite
launchers, they needed some RTL chips for replacement. They had some
problems finding such chips any longer


I like the power supply too
That sort of circuit was very common in those days.


Yes, the only IC used was a 3 input NOR gate. The effort got kicked of in 1963
and Fairchild Semiconductor was only 5 years old. Interesting - risking
a project on a technology in which understanding of fabrication, impurities,
bonding, etc. were just beginning.

I also recently came across this site - Apparently I wasn't the only one who
had the idea...

https://www.ibiblio.org/apollo/Pultorak.html

yes or one Microchip PIC.
Not sure how that would behave in radiation.


Happy reading.

As i vaguely remember,from speed testing of RTL, the rise time was
about 6nSec and the delay was about 7nSec.

hehe, I was thinking "AGC" normally means 'Automatic Gain Control'
and did a look up for what else it could stand for.

The wikipedia link about that AGC (the Apollo Guidance Computer one) I found
is very informative for an overview of what hey were doing,
the hardware and programming, with lots of pictures:
https://en.wikipedia.org/wiki/Apollo_Guidance_Computer

and indeed it was RTL (4100 chips),
and the second model even less it had 2800 RTL chips more integration.

What I do not see is the point (with all respect) of rebuilding it in FPGA or something,

So you can get to the Moon in 30 seconds.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Jon Elson]

On Thu, 25 Jul 2019 13:32:03 -0500, Jon Elson wrote:

Design was started about a year before the AGC, but finished a year
earlier, as it was a much simpler project, overall.

OOps, design was started a year LATER than the AGC.

Jon

 

[Tom Del Rosso]

Jan Panteltje wrote:

I like the power supply too
That sort of circuit was very common in those days.

That is one weird power supply. And the bridge seems to be rotated 90
degrees.

http://klabs.org/history/ech/agc_schematics/top_level/d7-el_power.jpg

 

[piglet]

On 26/07/2019 9:01 pm, Tom Del Rosso wrote:

Jan Panteltje wrote:

I like the power supply too
That sort of circuit was very common in those days.

That is one weird power supply. And the bridge seems to be rotated 90
degrees.

http://klabs.org/history/ech/agc_schematics/top_level/d7-el_power.jpg

Yes, the bridge is not rectifying the output to supply DC, the output to
the EL panels is AC - instead what I think the bridge is doing is
rectifying a feedback current control into the saturable core. Cute?

piglet

 

[Jan Panteltje]

On a sunny day (Fri, 26 Jul 2019 16:01:25 -0400) it happened "Tom Del Rosso"
<fizzbintuesday@that-google-mail-domain.com> wrote in
<qhfm6m$1qf$1@dont-email.me>:

Jan Panteltje wrote:

I like the power supply too
That sort of circuit was very common in those days.

That is one weird power supply. And the bridge seems to be rotated 90
degrees.

http://klabs.org/history/ech/agc_schematics/top_level/d7-el_power.jpg

At the risk of being totally wrong, I think it works this way:

It is a feedback circuit.
L2 is a transductor.
The bridge senses current and saturates the transductor via the winding marked 'control'.

It is an old design, was it named 'westat'?
Cannot find a circuit with google or, bing finds this:
https://patentimages.storage.googleapis.com/2a/30/4c/7054c260398bcc/US2179299-drawings-page-1.png
Not exactly like this, but using transductors for stabilizing power was very common in the sixties.
Anybody has some circuits?
Should have payed more attention to it back then, nut was using transistors and thyristors..
In that company where I worked there was a guy who was very good at that sort of thing.

It may be part of the display HV generation (note the text near pin 8)?

 

[piglet]

On 27/07/2019 7:47 am, Jan Panteltje wrote:

It may be part of the display HV generation (note the text near pin 8)?

Correct, 250V AC at 800Hz for the DSKY El panel display. The segments
were switched by lots of tiny TO-99 sized Teledyne relays.

The mag-amp current limiting may have distorted the waveform a bit - not
sure if C1 was to help resonate to more sine-like - I think waveform
probably didn't matter as long as there was no DC.

piglet