Page 21 - Concise Encyclopedia of Robotics

Alternative Computer Technology
states, the digits 1 and 0, represented by high and low electronic voltages.
No matter how complex the function, graphic, or program, the work-
ings of a digital computer can always be broken down into these two
logic states.
Digital computers can be made fast and powerful. They can work
with huge amounts of data, processing it at many millions of digits per
second. However, there are certain things that digital computers are
not good at doing. Some researchers think that other approaches to
computing deserve attention, even though digital technology has been
successful so far.
Analog processes
Whereas a digital machine breaks everything down into discrete bits
(binary digits), analog computer technology uses an entirely different
approach. Think of the square root of 2. This cannot be represented as a
ratio of whole numbers. A digital computer will calculate this and get
a value of about 1.414. However, a decimal-number representation of the
square root of 2 can never be exact. The best a digital machine can do is
get close to its true value.
The square root of 2 is the length of the diagonal of a square measuring
1 unit on a side. You can construct it with the tools of classical geometry
(an analog art) and get an exact rendition. But you cannot use this in
arithmetic as you use the numerical value 1.414. Thus, you sacrifice
quantitative utility for qualitative perfection.Perhaps similar give-and-take
will prove necessary in the quest to develop a computer that thinks like a
human being.Analog concepts have been adapted to computer design; in
fact, it was one of the earliest methods of computing. In recent years it
has been largely ignored.
Optics
Visible light, infrared (IR), and ultraviolet (UV) offer interesting possi-
bilities for the future of computer technology.
In CD-ROM (compact disk, read-only memory), optical technology
is used to increase the amount of data that can be stored in a given physical
space. Tiny pits on a plastic diskette cause a laser beam to be reflected or
absorbed at the surface. This allows encoding of many megabytes of data
on a diskette less than 15 cm across.
Data can be transmitted at extreme speeds, and in multiple channels,
via lasers in glass fibers. This is known as fiber-optic data transmission,
and is used in some telephone systems today. The wires in computers
might someday be replaced by optical fibers. The digital logic states, now
represented by electrical impulses or magnetic fields, would be represented

