Back in the day you had to go dig up an Adaptec 1542 or something similar if you wanted a CD-ROM on your Linux box. IDE CD-ROMs were essentially unsupported.

Best part of SCSI was the required sorcery. "No no, young padawan, you must put the terminator on the scanner, not on the hard drive, lest your device chain causes the computer to no longer boot."

I had a film scanner that would not work on any other SCSI ID that was not 4. Why? Because. Alacazam!