🚀 go-pugleaf

hbg6@phx.mcd.mot.com (John Schuch) writes:

>I was watching the PBS program "The Machine That Changed The World"
>last night ( the series deals with the history of computers ).
>They mentioned some sort of data storage device called a mercury
>tank. If I remember correctly it was used in the ENIAC computer
>system. Anybody know what it is or how it works?

      ENIAC didn't have mercury delay lines, just vacuum-tube
registers.  IAS, the Institute for Advanced Study machine designed
by Von Neumann, did, as did one of Turing's post-WWII machines.

      Delay line memory worked by using a mercury tank with a transducer
at each end as an acoustic delay line.  As bits were received at the
receiving end, they were reclocked and their level normalized, then
sent around again at the sending transducer.  The same bit pattern
could thus be recirculated indefinitely (more or less; this technology
was noise-sensitive and temperature dependent.)  As a memory, it
looked like a drum; you had to wait until the desired data came
around to read or replace it.  Inherently slow technology. 

					John Nagle