Comment by hilbert42
"That's why D was typically the CD-ROM:"
We used to set our machines so the CD-ROM was always drive L. This way we always had 'room' to add HDs so there was no gap in the alphabetical sequence. Drive D - data drive, E - swapfile, etc.
Test and external drives (being temporary) were assigned letters further down than L. Sticking reasonably rigidly to this nomenclature avoided stuff-up such as cloning an empty drive onto one with data on it (cloning was a frequent activity).
Incidentally, this rule applied to all machines, a laptop with HD would have C drive and L as the CD-ROM. Machines with multiple CD-ROMs would be assigned L, M and so on.
I always used J: (I didn’t expect to need to add that many hard drives).
I mainly did it so that CD installs wouldn’t lose their install drive since even Windows tracked it by the absolute path. Not as important with everything installed by download and Windows copying the install media to the hard drive anyway.