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Apollo Guidance Computer - facts from the horses mouths

Started by Unknown July 24, 2019
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

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.
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.
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.
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..
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.
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
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
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.
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.