positions. A successful crib run usually produced key of such length that wheel-
breaking was extremely easy. For this reason four Super-Robinsons were ordered to
overcome some of the handicaps which persisted on Old Robinson, and to include
spanning whose value had been proved on Colossus.
(k) Suggestions for a Super-Colossus.
Many suggestions are made in R4 pp 124-128 fundamental, trivial or even
Perhaps the most obvious development is the logical completion of devices to
deal with corruption, including spanning, on two or more stretches, slide-
correction without doctoring tapes, and not 99 for all purposes including
The difficulty of not 99 in rectangling is that the most straightforward
(though not the only) method demands the subtraction of a variable number. The
most satisfactory scheme would be a general facility so that, on the same counter,
some letters score positively and others negatively. A generalization would be
that scores from different runs could be added, each multiplied by an arbitrary
constant either positive or negative. Given either, wheel-breaking would require
no immediate simplification.
A small improvement would be the setting up of wheels by means of punched
(l) Suggestions for Robinson.
The most pressing needs are not 99 and a longer bedstead, but the latter is
a difficult mechanical problem. Multiple testing and a much larger plugboard and
switchboard are desirable.
(m) Synthesis of Robinson and Colossus.
There have been various suggestions for a combined Robinson-Colossus in
which all patterns are set up electrically, being of adjustable and in many cases,
very considerable length. These could be setup from a tape (as on Aquarius). A
further suggestion is that of making it possible to examine many positions
simultaneously (as on Proteus) : this however is more than a mere modification of
Colossus, and leads to such flights of fancy as a machine to combine two letters
by means of an arbitrary conversion square before counting them.