Transputers in space: SOHO (and others)

Today I Learnt there’s a transputer network in orbit round the Sun (and it’s not on Earth) - the SOHO vehicle, a solar observatory, uses transputers in some way for the image collection, processing, and/or transmission. It was launched in '95, is still operating, and has a pair of T800s for FPU work and a pair of T222s for control work.


The DPU consists of four transputers, two on the BCM and one on each CU. Each transputer has four links. The link concept aims at creating a redundant computer system. The links perform the following functions:

  • they exchange programs and data between the CUs and the BCMs,
  • they test the CUs and BCMs via the links,
  • they exchange commands for configuration etc,
  • they synchronize tasks between the CUs,
  • they load the development software to the CUs and BCMs,
  • they are used in debugging the software,
  • they communicate during parallel processing via the links.

The transputer links are placed so that each transputer is connected by more than one link. The faulty function of one link shall not lead to catastrophic errors of the DPU.

Also, elsewhere, we read

The CDS on-board processor hardware, called the Command and Data Handling System (CDHS), consists of one or two operating transputers (CPU’s), one standby transputer, memory, and subsystem interfaces. For convenience the two operating CPUs are here referred to as “primary” and “secondary”, and the standby CPU as “redundant”. These CPUs are interchangeable.


A bit of searching also shows up that there’s a microsatellite platform using T805s, which is prompting work on an ASIC replacement for the now-obsolete part: “The LENA ASIC: Emulating an Obsolete Processor”


Using transputer for redundancy makes a lot of sense. Which makes me wonder, was there any use in (terrestrial) avionics, as well?

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A quick web search suggests there was use in avionics. Indeed, the inestimable Gavin Crate says:

After leaving university, I joined an Avionics company where I banged on about Transputers so much that eventually I was involved in the design and development of a multiple Transputer based Avionics product which was very successful.

(Emphasis added!)


When you start a sentence like that, I worry that you’re about to tell us that it’s become self-aware or something. :wink:

That’s interesting to know. Before I ejected from academia I had colleagues who were analysing data from instruments on SOHO.