That was probably also some sort of drum memory mass storage device. Ours (we had 3) had a vertical cylinder about 20 inches diameter and 30 inches tall. Driven by about a 3 hp motor at 3600 rpm as I recall. Equally spaced around the diameter were 8 shafts that would rotate 1/4 turn. Each shaft had a gazillion heads mounted to it and when the shafts rotated, the heads were brought to the spinning cylinder. Total heads (in octal) 1777, I think. Complicated, touchy device. only 8mb storage. Very fast access though as you electronically turned on the head you wanted and just had to wait for the drum to rotate on revolution or less.
Oh, and I remember floppy disks that were about 11 inch dia. Jeeesh, I've been in this business too long.