Delay line memory

First described in the First Draft by #vonNeumann based on work by Eckert and Mauchley.
Information is stored as acoustic waves travelling through a medium, typically mercury. As sound travels more slowly than electric charge (light), if electric signals are converted to sound, the delay time involved can be used as a type of store.
It worked as follows:
- Imagine we have an 8-bit number. The number is input as a sequence of pulses where a pulse is 1 and the absence of a pulse is 0.
- The pulses are converted into sound waves (as with a speaker) and sent through a mercury-filled tube.
- The length of the tube