Drum memory
Drum memory was a form of computer memory. It was somewhat similar to modern hard drives, except that the media was cyndrical instead of disc-shaped. Drum memory was, to a certain extent, sequential, rather than random, like today's modern RAM, in that you had to wait for the section with your data to pass under the read/write head. In the Story of Mel, Mel used this property to avoid writing delay loops, by placing needed data in the most "pessimum" site on the drum, meaning that the computer had to wait for the data to be read.
Drum memory was eventually replaced by core memory when manufactoring of core was sent overseas. (Core memory had to be hand-woven, and was not practical until manufactoring was sent overseas, where labor was cheap.)