Comment by somethinsfishy

When the report was written there wasn't any random access memory. The only memory suited to computers in 1946 was the ultrasonic delay line as implemented by Eckert. What makes it not-random access is that all the bits in the store are being constantly shifted and counted in a loop (about 1Mhz?), so you have to wait for the word you want to read/write to fly past and the controller grabs it then.