Manx – a catalog of manuals for old computers
manx-docs.org
manx-docs.org
Not just random so-so scans with OCR. Sun, HP, and IBM, for example, had good online digital copies of many manuals, including made accessible to customers. Others looked like they might've produced their manuals entirely electronically, often using well-known tools that are still available today.
Some notable companies that no longer exist were acquired by companies that still exist, and who have customers of the kind that make you retain stuff.
For example, Boeing used Apollo Domain systems, and then HP acquired them, and now maybe HPE(?) has all those assets and didn't just throw them away? (Or, for that matter, Boeing might still have a lot of Apollo Computer stuff archived itself.)
For another example, Oracle might still have all of Sun's stuff. I recall at one point the manuals looked like they came out of FrameMaker, and then Sun was pushing NeWS (building on PostScript) so maybe getting "archival" PDF today would be easy?
DEC manuals are very noteworthy, but started much earlier, and there was quite a series of acquisitions journey, but maybe some of the document source survived?
I don't know about IBM mainframe and minicomputer manuals, but IBM was great about documentation in other areas, so hopefully that isn't being lost.
* Internet Archive
* http://mirrors.apple2.org.za and especially http://mirrors.apple2.org.za/Apple%20II%20Documentation%20Pr...
https://www.manualslib.com/manual/959633/Commodore-Vic-20.ht...
The brands I looked at, this site has on the order of 1% (or less) of manuals that existed. And the manual I tried to open was just a placeholder entry, saying that there is no known copy online.
For some niches (like for particular brands, or for a category like terminals), there are much more manuals already collected in a single place online.
I had a few but they went into the trash when I moved.
DON'T FORGET TO REMOVE LENS CAP!