b. Analog computers do not count. They measure continuous physical or
electrical magnitudes such as pressure, temperature, current, voltage length, or shaft
rotations. Analog devices have been in existence longer, a slide rule being one
example. Another is a gasoline pump, a device that measures the quantity and price of
gasoline. Yet another example is a car speedometer, with drive shaft rotations
converted to a number that indicates the speed. Analog devices are not as accurate as
the digital variety. Under ideal conditions, they function only within 0.1 percent
accuracy. It is important to note that while numerical results are obtained from an
analog computer, they are arrived at indirectly.
analog computer: used primarily in engineering and scientific computing, it
measures continuous physical or electrical magnitudes, such as pressure,
temperature, current voltage, and so forth.
Figure 2-2. This thermometer is an analog device. It perceives temperature
as a continuous function. A microprocessor converts the reading into
digital terms and advances the liquid crystal display (LCD) 2/10 of a
degree at a time. When the temperature stabilizes, the reading is
locked in and a beeper sounds.
DIGITAL COMPUTER FUNCTION
All digital computers, no matter what size or shape, have certain similarities in
the way they are organized. A computer must be able to read or accept instructions
and data, remember the problem solved and the data to use, perform arithmetical
calculations and logical manipulations on the data, read out the results, and control the
entire operation. The five functions of a computer are given in figure 2-3.
Figure 2-3. The five functions of a computer.