If you followed me for weird Voyager computer system facts, there will be none today :( No time, and it's looking increasingly likely that, to get the goods proper, I'll need to talk to the JPL archives and see how they might feel about getting a bunch of schematics from the Viking and Voyager collections cleared for publication. Which is going to require more homework to figure out what I need. And, frankly, "clearing for publication" doesn't sound like something quick and painless either.
I guess a couple facts I can definitely share: the more I find out about Voyager's computers, the more I admire them. They're the product of a solid decade of accumulated engineering, pioneers (not that one) in many ways, and also deeply compromised and influenced by the zeitgeist of cost-cutting. And yet the two systems that were built do so much with what they were given, and fair to say they've endured beyond the wildest hopes of anyone who put them together. How can you not be fascinated?
Hopefully I get to find out more, because the tiny voice in the back of the head going "I wonder how many gates it is, I bet you could totally build one" isn't going away, and I'm hoping it'll be enough to get over the awkwardness of cold emailing a hopefully friendly archivist while having no idea what I'm doing. We'll see. Until then, we'll see.
There's a new SFOS published though! I can't decipher the commands, but looks like more surgery starting on Friday next week maybe!
Maybe the Computer Museum folk could help out. Maybe they have some partial docs or something. They may have sufficient institutional mass to back you.
Okay I lied I couldn't let it go I tried to parse the new SFOS.
This Friday DSN is asking Voyager 1 for another AACS core dump. If memory serves they got one the other week after applying the FDS patch, so I wonder what that's about.
Next friday, there's an ominous sounding "CCS ERR ENTRY" being sent. Couldn't find any info on what that might be, but based on upload and download times it doesn't seem to involve any large data payloads.
Voyager 2 is also getting some routine upkeep commands.
Oh and the new schedule shows the correct telemetry mode now, EL-40 engineering data at a leisurely 40bps. Compare to Voyager 2, which is sending CR-5T containing a mix of science and engineering data, at a blazing 160bps. I don't see any note predicting return to CR-5T in the next two weeksfor Voyager 1, but that's not really surprising, the patient's stabilized (🤞) but still a fair bit of surgery needs doing.
@danderson does make me wonder what it’d be like to build (at least simulate) boards built with the constraint of similar manufacturing tech levels, but modern know how - like those modern 8bit pseudo consoles, but applied to space engineering
@raggi from what I can glean of the architecture (not much but not zero), aside from the plated wire memory the rest should all be doable in modern spins of 7400 series gates. The memory otoh... I do know where to procure beads for magnetic core memory, but plated wire was pretty niche even back in the day.
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