Computer Engineering and Nanotechnology - Molecular Computing: Origins and Promises - page 27

that the great Leonardo da Vinci drew up plans for an adding machine which was
reproduced in metal in our days and proved to be quite operational. This machine
operated with 13 digit-registering wheels.
2.1.1 A Little Detail: The Mechanical Calculators
The basic idea of such a device is shown in Fig. 2.1 . Suppose that each position of
an arbitrary decimal number corresponds to a shaft on which two gear wheels with
different numbers of operative teeth are mounted. Suppose that each shaft is set to
its initial position corresponding to the number “0.” Other numbers correspond to
subsequent rotations of the shaft by 36 . With a gear ratio between the gear wheels
at adjacent shafts equal to 1:10, the shaft corresponding to units must spin 10 times
by 36 to cause the shaft representing tens to move one position. This design allows
dialing any number limited only by the number of shafts and to add to or subtract
from it any number. Mechanical systems based on gear transmission were being
perfected and used almost until the middle of the last century. Back in the 1950s the
Soviet Army had in operational service the PUAZO antiaircraft artillery director
which determined correction for velocity, humidity, temperature, etc., while con-
trolling antiaircraft fire. PUAZO was a transportable cube with edges roughly one
meter in length stuffed with drive gears, worm gears, electric motors, etc.
Over the centuries that followed the Leonardo da Vinci era, outstanding scholars
from different countries—Blaise Pascal, Gottfried Leibniz, and Charles Babbage—
occupied themselves with the development of computer technology. However, by
the time the complex, cumbersome computations turned out to be vital, the level of
computing technology was inadequate for addressing the most pressing challenges.
Fig. 2.1 Scheme of a
mechanical computing
device