Fig 5-10 is the Data Management Subsystem
https://asd.gsfc.nasa.gov/archive/sm3a/downloads/sm3a_media_...
Concerning the computers:
- First they had a DF-224 flight computer and a
- Science Instrument Control and Data Handling (SI C&DH)
Initially DF-224 between missions got installed a coprocessor:
https://asd.gsfc.nasa.gov/archive/hubble/a_pdf/news/facts/Co...
During another servicing mission they replaced it with something called the Advanced Computer with Intel 80486:
https://asd.gsfc.nasa.gov/archive/hubble/a_pdf/news/facts/FS...
There are some 50,000 lines of code in the C and Assembly programming languages. https://www.nasa.gov/pdf/327688main_09_SM4_Media_Guide_rev1....
They also have a Help Desk...
"Welcome to the Hubble Space Telescope Help Desk"
"There's a backup module, with an override command to activate it, but it won't work with the system down. You'll have to use the manual override switch - on the telescope."
>> Hubble’s operators initially thought a memory module was at fault but switching to one of three backup modules produced the same error.
Apparently Hubble has 4 memory modules which are switchable! I'd love to see how that works. Actually, I'd be fascinated to get a walkthrough of the overall architecture. It might give insights for how we keep business continuity by first accepting that hardware and software will fail.