Here's a talk about how the Voyager team fixed the flight data computer on Voyager 1 when a memory chip went bad on it a few years ago. It goes over how the flight computer works and he walks through a few assembly routines. https://www.youtube.com/watch?v=YcUycQoz0zg

Some of the challenges they had to deal with while developing the fix:

- The only source code they had for the flight data software was an OCR'd Microsoft Word document (with typos) that was likely scanned from a hard copy assembler listing printout.

- The processor runs a custom instruction set developed by JPL for the Voyager mission. The documentation they had on the processor was incomplete.

- Everybody who had designed the flight software was dead.

- They had no assembler, no debugger, and no processor simulator. They had no testbed, the only two FDS processors were in space.

The 2025 YouTube video is "How We Diagnosed and Fixed the 2023 Voyager 1 Anomaly from 15 Billion Miles Away" by David Cummings of JPL.

There is a Vimeo video of the Voyager team reacting when data first began trickling in from Voyager 1 after the fix in April 2024. "Voyager 1 Team Reacts to Receiving Engineering Data From Spacecraft" (JPLraw channel): https://vimeo.com/939376171

Cummings is the one against the back wall who shoots his two arms up in the air in celebration. He and Armen Arslanian (in the blue shirt to his left, right in the image) developed the software fix.

The slides from Cummings' presentation can be downloaded as a PDF from the Flight Software Workshop Day 2 page, first entry: https://drive.google.com/drive/folders/1BXSBUgEJExsLSE-m585I...