Like the human body, the computer is composed of various peripheral "limbs"
and central organs that perform diverse functions. Peripherals or peripheral devices
include input-output units, secondary storage devices, and other auxiliary equipment.
Just as humans use their eyes to read information and send it to the brain, a computer
uses an input device that reads or accepts the information into a computer "brain," the
central processing unit (CPU). The information is read by the CPU and logical action is
taken according to a preset plan (program) that provides step-by-step instructions.
These components interact to solve problems, with numerical data instructions
constantly being sent back and forth between components. The entire process is
controlled by instructions provided in a software program. When the task is complete,
the results can be "memorized" into the computer memory. They can also be written or
punched on cards or tape by output devices.
read: to accept or obtain data from some source, as, for instance, a storage
write: to record or deliver data to a storage device, for example, to punch data
on cards in the form of a pattern of holes.
Figure 2-4. Computer components.
software: programs used to direct computer problem-solving and oversee
THE CENTRAL PROCESSING UNIT
a. The Central Processing Unit. Also known as the central processor or CPU,
this is the heart of the computer system. It selects, interprets, and executes program
instructions, stores data temporarily, maintains order, and directs overall functioning. It
does not perform actual processing operations on data. The CPU consists of three
parts: the arithmetic unit, the primary storage unit, and the control unit. The CPU is
often quite simply referred to as the computer.