Cracking old recovery CDs for the 9x/2000/XP era shines some light into how companies operated and when concepts came to be in that time:

Packard Bell: An EXE checks that you're running on a Packard Bell machine and reboots if it's not. How do we bypass it? Easy: just fucking delete it. The files to reinstall Windows from scratch come from...
...
C:?
Yup. Turns out Packard Bell was doing the recovery partition thing all the way back to the 9x era, maybe even further. Files aren't even on the restore disc so if your partition table got fucked (pretty common because malware and disk corruption) you were totally fucked and needed to repurchase Windows. (My dad, at the time, only charged at-cost OEM prices for a replacement retail copy. He knew it was dumb so he never sold PB machines.)

Compaq:
Computer check? Nope, remove one line from a BATCH file and it's gone.

Six archives, named "WINA.ZIP" through "WINF.ZIP" (plus one or two extras for OEM software) hold Windows. Problematic? Well... only because they never put the password anywhere so the installer can't install them. (Some interesting on-disc technician-only utils, though!)

Dell:
If not a Dell machine, lock up. Cause? CONFIG.SYS driver masquerading as OAK (the common CD driver) doing the check, then chainloading the real OAK driver. Simple fix: replace the fake driver with the real one.

Issues?

Would I mention this one if there weren't?

Disc is mounted on N:. Subdirectories work, but doing anything in them (a DIR, trying to execute something, trying to view shit in EDIT.COM) kicked you back to the disc root.

Installer couldn't find machine manifest in the MAP folder (it wanted your PC's serial before it'd let you install, to make sure you have the correct recovery disc) so it asked for 12-digit alphanumeric serial. The defined serials in the manifest were something like "02884902-01" or similar (8-2, all numbers) and it couldn't read the file so it couldn't show the right format, nor check for the right type.

Bypassing that issue, trying to do the ACTUAL install process caused nothing to happen... as all BATCHes for install think the CD should be on X:.

Welp.

well that was fun. Now to test on-real-PC behavior, as VBOX and VMWare both don't like the special hardware shit it tries to use. (Why does a textmode GUI need GPU acceleration, COMPAQ?????)