Landmarks in Digital Computing
INTRODUCTION
This book describes objects of special consequence to the
history of computing. The objects have been selected primarily
from the collections of the Smithsonian Institution.
From ancient times, people have used devices to assist them
in doing calculations. In some cultures, such as that of Greek
antiquity, Renaissance Europe, and China from at least the
seventeenth century, digital computing devices were a part of
everyday life. At the end of the nineteenth century, calculating
machines and cash registers became routine tools of business and
science, in the United States and elsewhere. Recently,
improvements in electronics have increased the capability and
decreased the cost of aids to computation. With the introduction
of the pocket calculator and personal computer, computing devices
came to be widely used at all levels of American society. At the
same time, special purpose computers made it possible to guide
missiles of immense destructive power and to land people on the
moon.
The rich collections of the Smithsonian Institution
illustrate the wide range of devices people have used over the
centuries. The collections are international in scope, with
special emphasis on objects made and used in the United States.
Both relatively inexpensive instruments produced in large numbersand unique devices highly advanced in their time are represented.
This book shows only a handful of most important objects among
the hundreds of digital computing devices in the collections.
The objects selected are intended to suggest the long and diverse
history of digital computing by including objects from different
cultures made over a period of hundreds of years.
The objects selected for this volume date from the
seventeenth to the twentieth century. Several are unique,
particularly models of nineteenth century calculating machines
and examples of early computers. Most were made and used in the
United States, although we include important objects from
elsewhere.
T he criteria for what constitutes a "landmark" vary, but we
hope not without purpose. Some machines were chosen because they
represent the first successful reduction of a key concept to
practice. Others represent machines that are more common but
which have had a profound impact on modern society; in this case
the Smithsonian's artifact may be no different from one that many
readers might see in their daily lives. In other cases we have
included devices not because they were important to the evolution
of computing technology, but simply because they are one of a
kind or else very rare, and as such are especially cherished by
the museum.
ANALOG AND DIGITAL
The aids to computation described here are all digital. In
other words, they handle numbers in discrete units, not as
continuous quantities. Analog devices, such as a ruler, reckon
by measuring rather than counting a physical quantity. Analog
devices range from a simple clock face, to medieval astrolabes,
drawing instruments, slide rules and integrators (devices used to
find the area bounded by closed curves). In the 1920s, complex
analog machines called differential analyzers were built to solve
problems in ballistics, electric power generation, and industrial
control. These machines were among the most complex, as well as
the most powerful computing tools available. But they were soon
eclipsed by the digital computers that followed them two decades
later. Why that happened will be discussed in connection with
the digital devices that displaced them.
Where photographs of the objects are available, the negative
number of the photographs is listed. Copies may be ordered from
the Smithsonian's Office of Printing and Photographic Services.
I. DIGITAL AIDS TO COMPUTATION
Objects or devices that helped people count and remember
numbers reach back into antiquity. The very act of recording a
numerical value by markings, which led to our present day number
system, also led to physical devices that assisted in
manipulating those quantities. Coins, counters and the abacus
were some of the first digital devices put to use. As arithmetic
became more generally known in Europe from the Renaissance
onward, such devices gradually gave way to written arithmetic.
As published books became less expensive, mathematical tables
also became widely available.
None of these devices are "machines," as they have no
interconnected moving parts. Their operation requires continuous
human control and guidance. An abacus, for example, can assist
in adding two numbers together, but the person using it must
participate in the details of the operation. Yet these
instruments did point the way toward machines that could carry
out all aspects of arithmetic, including multiplication,
division, and the automatic storage and retrieval of numbers.
Rev. 11/20/95