Re: is Ada used in James Webb Space Telescope software?

[John McCabe <john@mccabe.org.uk>]

On Monday, 27 December 2021 at 00:37:03 UTC, Paul Rubin wrote:
> John McCabe <jo...@mccabe.org.uk> writes: 

> > as it looked like we (Matra Marconi Space) might be forced to use the 
> > RTX2010 as it was one of very few space qualified processors with 
> > hardware floating point support. In the end we used the MA31750, with 
> > Ada, instead.

> Interesting. I hadn't heard of the MA31750 but it appears to be a 16 
> bit processor that implements the MIL-STD-1750A instruction set(!), 
> which I didn't know about either. Apparently it was made in the 1980s 
> but has since been superseded by SPARC architecture cpu's. 

There were 3 or 4 different implementations of the MIL-STD-1750A instruction set architecture around the time. It was an interesting one; it was fairly small, but had some relatively complex instructions that were really useful. The MA31750 was GEC-Plessey Semiconductors' 2nd version, I believe, although if I remember correctly, this was the one that had the FPU, or maybe it was the MMU, integrated into a single device, using silicon-on-sapphire for rad-hardness. There were two other implementations I particularly remember that were rad-hard, one by IBM, which had better claimed performance but was really expensive and special order only (I think we paid £7500 or so for each MA31750, so you may be able to imagine what I mean by "really expensive"), and one by another US company that went into Chapter 11 protection around the time we were talking to them! 

> I wonder if targeting GCC to the RTX2010 might have been feasible. 
> Can I ask what Ada compiler you used for the MA31750? It looks like GCC 
> supported the MA31750 until version 3.1, but I don't know whether GNAT 
> existed then.

I'm almost 100% sure GNAT wasn't available for the MIL-STD-1750A; it was a very niche market and we weren't aware of any C compilers we could've used at the time, even if we'd wanted to. 

The Ada compiler we used was the same as Nikolas; TLD. I was also working on part of ENVISAT (the Tile Control and Interface Unit - TCIU, although some of my colleagues were also using it on the main ASAR control system). Although Nikolas mentions Matra Marconi Space mandating TLD, that would've come down from Dornier who'd apparently done a deal with TLD. I don't know what happened with TLD after that, but some geezer from the Irvine Compiler Corporation contacted me once when they were following up on some unpaid license fees related to part of the TLD compiler.