http://www.straightdope.com/classics/a1_256b.html
“You would hire, say, a brass band, which you would surround with a phalanx of recording machines loaded with blank discs…”
Oops !
Hey, a disk is a cylinder, so a cylinder can be a disk.
Indeed, a disk is but a quite squat cylinder.
Topologically speaking, cylinder = disk. Cecil always speaks topologically. Chill out, dude.
Topologically, a donut is a picture frame. Don’t go too far.
From the OED.
Yahbut Cecil is talking about cylinders–says so later in the paragraph.