Dear colleagues in vintage computing ;-)
In the last years there has been substantial interest in the Apollo
Guidance Computer (AGC). So maybe someone might be interested what
happened outside of the United States in the 1960ties: Over the last few
years I restored a 920M computer which was (among others) used as the
guidance computer in the Europa rocket. This was the ancestor of the
European Ariane sapce launcher:
https://en.wikipedia.org/wiki/European_Launcher_Development_Organisation
Although not well known, this machine is a contemporary of the AGC, it
also uses integrated, SMD mounted circuits and is realized in DTL
techology (Diode Transistor Technology). Its word width is 18bit,
8k of core store where standard within a show-box sized chassis. 2us
and later down to 1us instruction time where stadnard. In contrast
to the AGC, this machine was a member of a whole series of airborne
computers - some of which are still in use TODAY (2021).
After core and the DTL chips became obsolete, this architecture even was
re-implemented by BAE systems using the AMD29XX chipset in the same
chassis as drop-in replacement.
The 920M never had core rope memory, and for rocket guidance 8k have
been enough although adding a 2nd box extending the core was possible.
Tte architecture is able to support up to 256k words of 18 bit.
Of course, the instruction set is very archaic - no carry flag, no stack
but it served its purpose with 18 bit choosen as the perfect word length
to give reasonable resolution without need for double-word calculation in
most applications;
http://www.programmer-electronic-control.de/Elliott920FactsCard.pdf
If this triggered some interest, you may watch my recently released video
on the 920M (covers applications, internals and some software is shown
running)...
https://www.youtube.com/watch?v=v-gF5g0nnoE
...or visit my project page regarding the work of restoring three
different members of this computer family to working condition:
http://www.programmer-electronic-control.de/index.html
Happy computing to all of you,
best wishes,
Erik.
P.S. Just wanted to point out, that also in Europe there have been relevant
developments regarding spaceborne computing in parallel to the Apollo
programme! In no ways I want to diminish the achievemets of the
Apollo development team...
''~``
( o o )
+------------------------.oooO--(_)--Oooo.--------------------------+
| Dr. Erik Baigar Inertial Navigation & |
| e...@baigar.de .oooO Vintage Computer |
| www.baigar.de ( ) Oooo. Hobbyist |
+---------------------------\ (----( )----------------------------+
\_) ) /
(_/
Dr. Erik Baigar
Scientific Lead Spectroscopy Systems
Technologie Team Spectroscopy
THORLABS GmbH
M?nchner Weg 1
85232 Bergkirchen
Germany
Tel.: +49 (0) 8131 5956-40147
Fax.: ?+49 (0) 8131 5956-99
Mail: ?ebai...@thorlabs.com
Web: ?www.thorlabs.com
General Manager: Dr. Bruno Gross
HRB No: 85345, M?nchen
