Station wagon full of bits


Geof Cooper (imagen!apolling!geof@decwrl.DEC.COM)
Tue, 24 Mar 87 13:39:06 pst


> In article <8703220422.AA13307@buita.bu.edu> jsol@buit1.bu.EDU writes:
> > From: Scott Earley < > > From: Scott Earley <EARLEY@BITNIC>
> >
> > ... Tables
> > for all sites on the Ohio side of the PSU-Ohio link will be put
> > on tape and mailed overnight to a pre-appointed individual who
> > will reintroduce them into the network from there.
> > ...
> >
> >That's right. Mag tape.
> >
> >--Daemon
>
> Never underestimate the bandwidth of a station wagon full of magtapes!
>

Well, we can't resist this, can we. Back of the envelope calculations
for a station wagon full of bits transmitted from the east coast to the
west coast follow. Apologies for any naivitee about magtapes -- I don't
use them often and never learned all the sordid details.

    Station wagon: 5' X 5' X 3' trunk
    Transit time: 4 days = 345 600 s
     (might add a day on each side to copy the data to & from tape)
    Data:
        1 magtape, 12"X1" reel, 1000' of tape, 9600 bpi, 9 tracks
            => 12*1000*9600*9 = 129.6 E 6 bits
        5*5*36 = 875 magtapes in trunk

        => 875*129.6 = 113.4 E 9 bits

    Throughput:
        113.4e9 b / 345600 s = 328,125 b/s

Hmm.... better than the arpanet.... how much does a station wagon
cost these days, anyway...

Corrections welcome (they might as well be, I'm sure there will
be some!),

- Geof



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