Friday, 25 March 2016
Software
Computer software also called a program or simply software is a series
of instructions that directs a computer to perform specific tasks or
operations. Computer software consists of computer programs, libraries
and related non-executable data (such as online documentation or digital
media). Computer software is intangible, contrasted with computer
hardware, which is the physical component of computers. Computer
hardware and software require each other and neither can be
realistically used on its own.
At the lowest level, executable code consists of machine language
instructions specific to an individual processor—typically a central
processing unit (CPU). A machine language consists of groups of binary
values signifying processor instructions that change the state of the
computer from its preceding state. For example, an instruction may
change the value stored in a particular storage location in the
computer—an effect that is not directly observable to the user. An
instruction may also (indirectly) cause something to appear on a display
of the computer system—a state change which should be visible to the
user. The processor carries out the instructions in the order they are
provided, unless it is instructed to "jump" to a different instruction,
or interrupted.
Software written in a machine language is known as "machine code".
However, in practice, software is usually written in high-level
programming languages that are easier and more efficient for humans to
use (closer to natural language).[1] High-level languages are translated
into machine language using a compiler or an interpreter or a
combination of the two. Software may also be written in a low-level
assembly language, essentially, a vaguely mnemonic representation of a
machine language using a natural language alphabet, which is translated
into machine language using an assembler.