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

formulation of the machine- (See Ref . No„ 1 cited.) Considerable con-
struction of duplicative nature and some mechanical and technical
refinement remained to be done (much of which has since been accomplished-
1-2
see ref No, 7 cited) , but at this date it already seemed clear that the
major uncertainties as to realizeability of the apparatus had been
resolved and that techniques had been evolved permitting straight-
forward design and full-scale completion of these parts with high
expectation of success,
4) There remains to be discussed the "inner" section of the
memory organ (b); the organization of the computer probably hinges more
heavily upon the performance of this unit than upon siny other single
item, A memory device from which very high performance is expected
the "Selectron" tube'—is under development at the Princeton Ia.boratories
of RCA, and many refinements and much <strong>progress</strong> toward its perfection
have been made. The estimated performance figures of the Selectron
played a central role in the planning and organization of the entire
computer, and this device or its equivalent seem as vital now to the
completion of an adequate computing machine as when the original
plans were formulated in 1946.
5)
By January 1948 work on the Selectron had certainly
brought the tube much closer to completion, and although no doubt
remained as to eventual success of the development, it did not seem
possible to predict the date when these tubes would be available in
sufficient quantity to permit operation of the computer even on a
—