Interconnected Punched Card Equipment The first
automated scientific computations
Photo: [9].
IBM 285 Tabulator, 016 Punch, Switch Box, 601 Multiplying Punch.
Professor Wallace Eckert's punched-card machine
setup for the integration of differential equations --
the first automated scientific calculations,
Rutherford Observatory,
Pupin Hall, Columbia University, 1934.
Left to right: an IBM Type 285 Tabulator, an
IBM Duplicating Punch,
the calculation control switch, and the IBM Type
601 Multiplying Punch. The control switch was Eckert's innovation, built
to his specifications by IBM's
Stephen
"Red" Dunwell [59]
(who would later head IBM's
STRETCH
project [57]) at Endicott NY.
"All switching of the machines to change from one operation to another is
performed automatically by means of the calculation control switch. Thus
the machines are always ready to perform the next computation when the last
has been completed. ... It
contains a row of electric contacts each of which is operated by a rotating
cam. The cam is a circular fiber disk which is notched at various points
around the circumfrence. A series of about twenty of these disks are attached
to a common shaft to form a sort of player piano roll.
Rotating cams in switch box;
Photo:[103].
When this roll is rotated from one position to the next the various contacts
open and close according to the notches in the disks. The circuits from the
contacts are used to operate the various control switches on the tabulator
and multiplier, and also a number of multicontact relays which effectively
change the wiring of the plugboards. Each
step in the integration consists of a certain number of distinct machine
operations which always come in the same order. Hence in order to have the
machines ready for each operation it is only necessary to rotate the roll
from one position to the next, one complete revolution corresponding to a
complete step in the integration. One roll serves for all equations of a
given form, and a new one could be prepared in a few
hours" [50].
Dr. Eckert said in a 1964 interview [51],
"It was a revolutionary thing, because up until that time general scientific
computing always involved hand work. The numbers had to be copied. The
arithmetic had to be done at best with a desk calculator or with logarithms,
and here for the first time you could do general things such as the solution
of a differential equation completely automatically and you never had to read
or write a number."
L.J. Comrie performed scientific computations using
punch-card equipment some years earlier (beginning in 1928) at H.M. Nautical
Almanac Office, Greenwhich, England. Comrie's method was a great improvement
in both speed and accuracy over hand copying. Comrie's calculations were done
one step at a time. Manual intervention was required to transfer intermediate
results punched onto cards to subsequent reading stations and/or to swap or
rewire control panels between steps. Eckert's method was the first to enable
a complex series of calculations to be "programmed" to run to completion, an
idea first envisioned by Charles Babbage 100 years earlier.
In fact Eckert's 1934 calculations were not entirely automatic; a modest
amount of operator intervention was required as described on pages
108-111 of [50], owing mainly to
limitations of the original switchbox and machines. However, the principals
of automatic sequencing had been established, and were carried forward and
fully realized in the
Aberdeen machines (1944),
SSEC (1946),
Card Programmed Calculator (1948), and
NORC (1954). (And of course also, independently, in
ASCC (Harvard Mark 1),
ENIAC et al., but these were done with full
knowledge of Eckert's pioneering work.) As Pugh
says [40], "this cam-sequenced calculator
was a pioneering early step toward stored-program digital computers."
Herb Grosch clarifies the manual intervention:
Eckert "used the ... 601 as a desk calculator, passing one [time step] card
-- or at some stages, three: one each for x,y,z -- through a cycle of
plugboards, which was actually a single in-place control panel the wiring of
which was modified by the master circuit breaker in his custom-built "switch".
Each step on the switch changed the 601 op, usually by selecting as an input
the field just punched as an output on the preceding step. Eckert then re-fed
the card (he told me he sat on a strategically-placed stool and extended his
reach with a clothespin on a short rod!). Then he cycled to the next switch
position, re-re-fed the poor abused card, and so on."
Comrie, L.J., "On the Construction of Tables by Interpolation",
Monthly Notices of the Royal Astronomical Society,
Vol. 88, pp. 518-521 (1928).
Comrie, L.J., "The application of the Hollerith Tabulating Machine to
Brown's Tables of the Moon",
Monthly Notices of the Royal Astronomical Society,
Vol. 92, No.7, pp.694-707 (1932).
Eckert, W.J., "Numerical Integration wiht the Aid of Hollerith Machines",
Publications of the American Astronomical Society, Vol.8, No.1,
p.9 (1934).
Eckert, W.J., "Miscellaneous Research Applications: Astronomy", in Baehne,
G.W. (ed.) Practical Applications of the Punched Card Method in
Colleges and Universities, Columbia University Press (1935).
Eckert, W.J., "The Computation of Special Perturbations by the Punched
Card Method", The Astronomical Journal, Vol.XLIV, No.20, Albany
NY (24 Oct 1935).
Eckert, W.J., Punched Card Methods in Scientific Computation,
The Thomas J. Watson Astronomical Computing Bureau, Columbia University,
Lancaster Press, Inc., Lancaster PA (January 1940). "The Orange Book."
Reprinted in 1984 by the Charles Babbage Institute, MIT, and Tomash Publishers
with a new introduction by J.C. McPherson.
An
Interview with Stephen Dunwell, OH 153, Conducted by William Asprey,
Charles Babbage Institute, Center for the History of Information
Processing, University of Minnesota, Minneapolis, 13 February 1989 (pages
30-31).