First progress report on a multi-channel magnetic drum inner ...

VIII. Modus Operandi and Circuit Organization
VIII-1
1) The necessity of using at least "several" identical recording-
reading channels has been remarked elsewhere in this <strong>report</strong> (II ^a.T.U-t)
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and arises from the high digit scanning rate (2x10 per second). It is
now appropriate to set some more concrete bounds on this and other variables
left unspecified up to this point.
2) It has been indicated that velocities of the magnetic surface
on the order of one or two thousand linear inches per second are quite
manageable and should introduce no special problems; consider 1000 inches
per second, and choose some likely density of recorded digits, say 50
per inch. This would lead to & scan rate of 5x10 digits per second per
channel on the drum, and so forty similar channels would be necessary to
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achieve a scan rate of 2x10 digits per second. This seems a reasonable
figure to fix upon for several reasons:
a) It meets the required scan rate under the concurrently
pessimistic conditions of digit resolution—of only 50 to
the inch (experiments of the previous section indicated
twice this figure) and velocity of only 1000 linear inches
per second (2000 would still be conservative)
b) It affords more flexibility in the direction of mode of
operation; namely, simultaneous parallel read-in and read-
out of entire 40 digit words can be effected if desired;
c) Variables known to have sharp upper bounds of performance
are underrated in what is probably a consistent manner;