From Wikipedia, the free encyclopedia
Computer software or just
software, is a collection of
computer programs and related
data that provides the instructions for telling a
computer
what to do and how to do it. Software refers to one or more computer
programs and data held in the storage of the computer for some purposes.
In other words, software is a set of
programs, procedures, algorithms and its
documentation concerned with the operation of a data processing system. Program software performs the
function of the
program it implements, either by directly providing
instructions to the computer hardware or by serving as input to another piece of software. The
term was coined to contrast to the old term
hardware (meaning physical devices). In contrast to hardware, software "cannot be touched".
[1] Software is also sometimes used in a more narrow sense, meaning
application software
only. Sometimes the term includes data that has not traditionally been
associated with computers, such as film, tapes, and records.
[2]
Computer software is so called to distinguish it from
computer hardware,
which encompasses the physical interconnections and devices required to
store and execute (or run) the software. At the lowest level,
executable code consists of machine language instructions specific to an
individual processor. A machine language consists of groups of binary
values signifying processor instructions that change the state of the
computer from its preceding state. Programs are an ordered sequence of
instructions for changing the state of the computer in a particular
sequence. It is usually written in
high-level programming 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 language using a
natural language alphabet. Assembly language must be assembled into
object code via an
assembler.
[edit] History
The first theory about software was proposed by
Alan Turing in his 1935 essay
Computable numbers with an application to the Entscheidungsproblem (Decision problem).
[3] The term "software" was first used in print by
John W. Tukey in 1958.
[4] Colloquially, the term is often used to mean application software. In computer science and
software engineering, software is all
information processed by
computer system, programs and
data.
[4] The academic fields studying software are
computer science and
software engineering.
The history of computer software is most often traced back to the first
software bug in 1946
[citation needed].
As more and more programs enter the realm of firmware, and the hardware
itself becomes smaller, cheaper and faster as predicted by
Moore's law,
elements of computing first considered to be software, join the ranks
of hardware. Most hardware companies today have more software
programmers on the payroll than hardware designers
[citation needed], since software tools have automated many tasks of
Printed circuit board engineers. Just like the
Auto industry, the
Software industry has grown from a few visionaries operating out of their garage with
prototypes.
Steve Jobs and
Bill Gates were the
Henry Ford and
Louis Chevrolet of their times
[citation needed], who capitalized on ideas already commonly known before they started in the business. In the case of
Software development, this moment is generally agreed to be the publication in the 1980s of the specifications for the
IBM Personal Computer published by
IBM employee
Philip Don Estridge. Today his move would be seen as a type of
crowd-sourcing.
Until that time, software was
bundled with the hardware by
Original equipment manufacturers (OEMs) such as
Data General,
Digital Equipment and IBM
[citation needed]. When a customer bought a
minicomputer, at that time the smallest computer on the market, the computer did not come with
Pre-installed software,
but needed to be installed by engineers employed by the OEM. Computer
hardware companies not only bundled their software, they also placed
demands on the location of the hardware in a refrigerated space called a
computer room.
Most companies had their software on the books for 0 dollars, unable to
claim it as an asset (this is similar to financing of popular music in
those days). When Data General introduced the
Data General Nova, a company called Digidyne wanted to use its
RDOS operating system on its own
hardware clone. Data General refused to
license their software (which was hard to do, since it was on the books as a free asset), and claimed their "bundling rights". The
Supreme Court
set a precedent called Digidyne v. Data General in 1985. The Supreme
Court let a 9th circuit decision stand, and Data General was eventually
forced into licensing the Operating System software because it was ruled
that restricting the license to only DG hardware was an illegal
tying arrangement.
[5] Soon after, IBM 'published' its
DOS source for free,
[citation needed] and
Microsoft was born. Unable to sustain the loss from lawyer's fees, Data General ended up being taken over by
EMC Corporation. The Supreme Court decision made it possible to value software, and also purchase
Software patents.
The move by IBM was almost a protest at the time. Few in the industry
believed that anyone would profit from it other than IBM (through free
publicity). Microsoft and
Apple
were able to thus cash in on 'soft' products. It is hard to imagine
today that people once felt that software was worthless without a
machine. There are many successful companies today that sell only
software products, though there are still many common software licensing
problems due to the complexity of designs and poor documentation,
leading to
patent trolls.
With open software specifications and the possibility of software
licensing, new opportunities arose for software tools that then became
the
de facto standard, such as DOS for operating systems, but also various proprietary word processing and
spreadsheet programs. In a similar growth pattern, proprietary development methods became standard
Software development methodology.
[edit] Types of software
Software includes all the various forms and roles that digitally stored
data may have and play in a computer (or similar system), regardless of whether the data is used as
code for a CPU, or other
interpreter, or whether it represents other kinds of
information. Software thus encompasses a wide array of products that may be developed using different techniques such as ordinary
programming languages,
scripting languages,
microcode, or an
FPGA configuration.
The types of software include
web pages developed in languages and frameworks like
HTML,
PHP,
Perl,
JSP,
ASP.NET,
XML, and
desktop applications like
OpenOffice.org,
Microsoft Word developed in languages like
C,
C++,
Objective-C,
Java,
C#, or
Smalltalk.
Application software usually runs on an underlying software
operating systems such as
Linux or
Microsoft Windows. Software (or
firmware) is also used in
video games and for the configurable parts of the
logic systems of
automobiles,
televisions, and other
consumer electronics.
Practical
computer systems divide
software systems into three major classes
[citation needed]:
system software,
programming software and
application software, although the distinction is arbitrary, and often blurred.
[edit] System software
System software is
computer software designed to operate the
computer hardware to provide basic functionality and to provide a platform for running
application software.
[6][7] System software includes
device drivers,
operating systems,
servers,
utilities, and
window systems.
System software is responsible for managing a variety of independent
hardware components, so that they can work together harmoniously. Its
purpose is to unburden the
application software programmer from the often complex details of the particular computer being used, including such accessories as
communications devices,
printers, device readers, displays and keyboards, and also to partition
the computer's resources such as memory and processor time in a safe
and stable manner.
[edit] Programming software
Programming software include tools in the form of programs or
applications that software developers use to create, debug, maintain, or
otherwise support other programs and applications. The term usually
refers to relatively simple programs such as
compilers,
debuggers,
interpreters,
linkers, and
text editors,
that can be combined together to accomplish a task, much as one might
use multiple hand tools to fix a physical object. Programming tools are
intended to assist a programmer in writing
computer programs, and they may be combined in an
integrated development environment (IDE) to more easily manage all of these functions.
[edit] Application software
Application software
is developed to perform in any task that benefits from computation. It
is a set of programs that allows the computer to perform a specific data
processing job for the user. It is a broad category, and encompasses
software of many kinds, including the
internet browser being used to display this page. This category includes:
[edit] Software topics
[edit] Architecture
Users often see things differently than programmers. People who use modern general purpose computers (as opposed to
embedded systems,
analog computers and
supercomputers) usually see three layers of software performing a variety of tasks: platform, application, and user software.
- Platform software: Platform includes the firmware, device drivers, an operating system, and typically a graphical user interface which, in total, allow a user to interact with the computer and its peripherals (associated equipment). Platform software often comes bundled with the computer. On a PC you will usually have the ability to change the platform software.
- Application software: Application software
or Applications are what most people think of when they think of
software. Typical examples include office suites and video games.
Application software is often purchased separately from computer
hardware. Sometimes applications are bundled with the computer, but that
does not change the fact that they run as independent applications.
Applications are usually independent programs from the operating system,
though they are often tailored for specific platforms. Most users think
of compilers, databases, and other "system software" as applications.
- User-written software: End-user development tailors systems to meet users' specific needs. User software include spreadsheet templates and word processor
templates. Even email filters are a kind of user software. Users create
this software themselves and often overlook how important it is.
Depending on how competently the user-written software has been
integrated into default application packages, many users may not be
aware of the distinction between the original packages, and what has
been added by co-workers.
[edit] Documentation
Most software has
software documentation so that the
end user
can understand the program, what it does, and how to use it. Without
clear documentation, software can be hard to use—especially if it is
very specialized and relatively complex like
Photoshop or
AutoCAD.
Developer documentation may also exist, either with the code as
comments and/or as separate files, detailing how the programs works and
can be modified.
[edit] Library
An executable is almost always not sufficiently complete for direct execution.
Software libraries include collections of
functions
and functionality that may be embedded in other applications. Operating
systems include many standard Software libraries, and applications are
often distributed with their own libraries.
[edit] Standard
Since software can be designed using many different
programming languages and in many different
operating systems and
operating environments,
software standard is needed so that different software can understand and exchange information between each other. For instance, an
email sent from a
Microsoft Outlook should be readable from
Yahoo! Mail and vice versa.
[edit] Execution
Computer software has to be "loaded" into the
computer's storage (such as the
hard drive or
memory). Once the software has loaded, the computer is able to
execute the software. This involves passing
instructions from the application software, through the system software, to the hardware which ultimately receives the instruction as
machine code. Each instruction causes the computer to carry out an operation – moving
data, carrying out a
computation, or altering the
control flow of instructions.
Data movement is typically from one place in memory to another.
Sometimes it involves moving data between memory and registers which
enable high-speed data access in the CPU. Moving data, especially large
amounts of it, can be costly. So, this is sometimes avoided by using
"pointers" to data instead. Computations include simple operations such
as incrementing the value of a variable data element. More complex
computations may involve many operations and data elements together.
[edit] Quality and reliability
Software quality is very important, especially for commercial and system software like
Microsoft Office,
Microsoft Windows and
Linux.
If software is faulty (buggy), it can delete a person's work, crash the
computer and do other unexpected things. Faults and errors are called "
bugs." Many bugs are discovered and eliminated (debugged) through
software testing.
However, software testing rarely – if ever – eliminates every bug; some
programmers say that "every program has at least one more bug"
(Lubarsky's Law). All major software companies, such as Microsoft,
Novell and
Sun Microsystems, have their own software testing departments with the specific goal of just testing. Software can be tested through
unit testing,
regression testing
and other methods, which are done manually, or most commonly,
automatically, since the amount of code to be tested can be quite large.
For instance,
NASA
has extremely rigorous software testing procedures for many operating
systems and communication functions. Many NASA based operations interact
and identify each other through command programs called software. This
enables many people who work at NASA to check and evaluate functional
systems overall. Programs containing command software enable hardware
engineering and system operations to function much easier together.
[edit] License
The software's license gives the user the right to use the software
in the licensed environment. Some software comes with the license when
purchased off the shelf, or an OEM license when bundled with hardware.
Other software comes with a
free software license, granting the recipient the rights to modify and redistribute the software. Software can also be in the form of
freeware or
shareware.
[edit] Patents
Software can be patented in some but not all countries; however,
software patents
can be controversial in the software industry with many people holding
different views about it. The controversy over software patents is about
specific
algorithms or techniques that the software contains, which may not be duplicated by others and considered
intellectual property and
copyright infringement depending on the severity.
[edit] Design and implementation
Design and implementation of software varies depending on the complexity of the software. For instance, design and creation of
Microsoft Word software will take much more time than designing and developing
Microsoft Notepad because of the difference in functionalities in each one.
Software is usually designed and created (coded/written/programmed) in
integrated development environments (IDE) like
Eclipse,
Emacs and
Microsoft Visual Studio that can simplify the process and
compile the program. As noted in different section, software is usually created on top of existing software and the
application programming interface (API) that the underlying software provides like
GTK+, JavaBeans or
Swing. Libraries (APIs) are categorized for different purposes. For instance,
JavaBeans library is used for designing
enterprise applications,
Windows Forms library is used for designing graphical user interface (GUI) applications like
Microsoft Word, and
Windows Communication Foundation is used for designing
web services. Underlying
computer programming concepts like
quicksort,
hashtable,
array, and
binary tree
can be useful to creating software. When a program is designed, it
relies on the API. For instance, if a user is designing a Microsoft
Windows desktop application, he/she might use the
.NET Windows Forms library to design the desktop application and call its APIs like
Form1.Close() and
Form1.Show()[8]
to close or open the application and write the additional operations
him/herself that it need to have. Without these APIs, the programmer
needs to write these APIs him/herself. Companies like
Sun Microsystems,
Novell, and
Microsoft provide their own APIs so that many applications are written using their
software libraries that usually have numerous APIs in them.
Computer software has special economic characteristics that make its
design, creation, and distribution different from most other economic
goods.
[specify][9][10]
A person who creates software is called a
programmer,
software engineer,
software developer, or
code monkey, terms that all have a similar meaning.
[edit] Industry and organizations
A great variety of software companies and programmers in the world
comprise a software industry. Software can be quite a profitable
industry:
Bill Gates, the founder of
Microsoft was the richest person in the world in 2009 largely by selling the
Microsoft Windows and
Microsoft Office software products. The same goes for
Larry Ellison, largely through his
Oracle database software. Through time the software industry has become increasingly specialized.
Non-profit software organizations include the
Free Software Foundation,
GNU Project and
Mozilla Foundation. Software standard organizations like the
W3C,
IETF develop software standards so that most software can interoperate through standards such as
XML,
HTML,
HTTP or
FTP.
