This switch clears the display and all scores which are in storage.
54H CONTROL TAPES
A control tape is one used to select a set of places on another tape whereon
a count is to be made.
These places may be all consecutive, or in in la ed groups, either regular
(b) Spanning by means of control tapes
In particular if all the places are consecutive, and if still more
particularly the tape steps in unison with the tape from which the start is taken,
a control tape is equivalent to spanning. Spanning by dials has of course the
advantage that it can be adjusted rapidly, and if the spanning required is not
known beforehand this advantage is overwhelming.
Spanning by a control tape was used for some early versions of mechanical
flags and rectangles, in which several different spans are needed: the spans were
represented on the control tape by different letters, and selected by means of a
letter count which is easier than respanning. This was discontinued when the
split score counter was introduced only because it absorbed too many of the
conditions which can be imposed on the bb half-count.
A compromise, spanning large pieces of text by dial and subdividing these by
a control tape is quite feasible.
Old Robinson has no span counter so that spanning had to be effected by
control tape, or more commonly by a control impulse replacing an impulse of the
tape to be counted. This was often necessary because the minimum text length was
(c) Irregularly spaced selection
Wen the places to be selected are not consecutive a control tape or impulse
must be used: the method is obvious: it can be employed to eliminate corrupt
(d) Regularly spaced selection
Some simplification is usually possible: the length of the control tape can
be any multiple of the cycle which can be put on the bedstead. A proper choice
for the length of the other tape will usually suffice for any stepping required. A
good example is the 1+2 rectangle [24 B ( e)]
(e) Number of different selections made by one tape
A single control tape /9/H/T and so on can, by imposing the conditions
Cfwd = 9, C = 9, Cfwd = H, C = H, and so on, be made to select a cycle of 62 or
A single impulse of a tape with the pattern xxxx....xx.x..x.. can, by use
of Cfwd, C, Coneback, Ctwoback, be made to select a cycle of 16 places.