> Because sound moved at a slow rate through a medium like mercury
Actually, it moves pretty fast through mercury; 1450 m/s.
> each I guess storing one bit. (...) Does anyone know if this a correct understanding of how this kind of storage worked?
From the Wikipedia article:
> Typically many pulses would be "in flight" through the delay, and the computer would count the pulses by comparing to a master clock to find the particular bit it was looking for.
> EDSAC, designed to be the first stored-program digital computer, began operation with 512 35-bit words of memory, stored in 32 delay lines holding 576 bits each
> The average access time was about 222 microseconds
Hmm... That would be a memory loop time of 444 us. At a speed of 1450 m/s, you need a delay line at least 64.38 cm long. And you'd need an impressive 1.3 Mb/s data transmission rate.
Another interesting fact:
> Since the speed of sound changes with temperature (because of the change in density with temperature) the tubes were heated in large ovens to keep them at a precise temperature. Other systems instead adjusted the computer clock rate according to the ambient temperature to achieve the same effect.
The tubes are 5 feet long (the whole tank is about 6' including the transducers at each end). I think that tank holds 16 tubes, so I'm guessing from the figures in geon's post that there must have been another tank too.
Actually, it moves pretty fast through mercury; 1450 m/s.
> each I guess storing one bit. (...) Does anyone know if this a correct understanding of how this kind of storage worked?
From the Wikipedia article:
> Typically many pulses would be "in flight" through the delay, and the computer would count the pulses by comparing to a master clock to find the particular bit it was looking for.
> EDSAC, designed to be the first stored-program digital computer, began operation with 512 35-bit words of memory, stored in 32 delay lines holding 576 bits each
> The average access time was about 222 microseconds
Hmm... That would be a memory loop time of 444 us. At a speed of 1450 m/s, you need a delay line at least 64.38 cm long. And you'd need an impressive 1.3 Mb/s data transmission rate.
Another interesting fact:
> Since the speed of sound changes with temperature (because of the change in density with temperature) the tubes were heated in large ovens to keep them at a precise temperature. Other systems instead adjusted the computer clock rate according to the ambient temperature to achieve the same effect.