Computers today. Гурьянова В.И. - 22 стр.

                                  Computer software
      Software, consisting of programs, enables a computer to perform specific
tasks, as opposed to its physical components (hardware) which can only do the
tasks they are mechanically designed for. The term includes application software
such as word processors which perform productive tasks for users, system soft-
ware such as operating systems, which interface with hardware to run the neces-
sary services for user-interfaces and applications, and middleware which con-
trols and coordinates distributed systems.

                           Relationship to computer hardware

      Computer software is so called in contrast to computer hardware, which
encompasses the physical interconnections and devices required to store and
execute (or run) the software. In computers, software is loaded into RAM and
executed in the central processing until. At the lowest level, software consists of
a machine language specific to an individual processor. A machine language
consists of groups of binary values signifying processor instructions (object
code), which change the state of the computer from its preceding state. Software
is an ordered sequence of instructions for changing the state of the computer
hardware in a particular sequence. It is usually written in high-level program-
ming languages that are easier and more efficient for humans to use (closer to
natural language) than machine language. High-level languages are compiled or
interpreted into machine language object code. Software may also be written in
an assembly language, essentially, a mnemonic representation of a machine lan-
guage using a natural language alphabet. Assembly language must be assembled
into object code via an assembler.

                                          Types

      Practical computer systems divide software systems into three major
classes: system software, programming software and applications software, al-
though the distinction is arbitrary, and often blurred.
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