Originally (1947) EDSAC boasted [sic] 512 words of main memory stored in 16 ultrasonic mercury-delay-line tanks, cleverly known as "long" tanks because they were longer then the short tanks used for registers.  On the bright side, as we used to quip, each of the 512 words was 18 bits!  Forget the word count, feel the width!  Alas, for technical reasons, only 17 of the 18 bits were accessible.  By 1952, the number of long tanks had doubled, providing a dizzy total of 1-KB words.  Input/output was via five-track paper tape, which therefore also served as mass [sic] storage.  Subject only to global timber production, one might see this as virtually unlimited mass storage…

-Stan Kelly-Bootle, writing in the current issue of the ACM Queue, Will The Real Bots Please Stand Up?