Microprocessor

A microprocessor incorporates most or all of the functions of a central processing unit (CPU) on a single integrated circuit (IC). The first microprocessors emerged in the early 1970s and were used for electronic calculators, using BCD arithmetics on 4-bit words. Other embedded uses of 4 and 8-bit microprocessors, such as terminals, printers, various kinds of automation etc, followed rather quickly. Affordable 8-bit microprocessors with 16-bit addressing also led to the first general purpose microcomputers in the mid-1970s.
Processors were for a long period constructed out of small and medium-scale ICs containing the equivalent of a few to a few hundred transistors. The integration of the whole CPU onto a single VLSI chip therefore greatly reduced the cost of processing capacity. From their humble beginnings, continued increases in microprocessor capacity have rendered other forms of computers almost completely obsolete , with one or more microprocessor as processing element in everything from the smallest embedded systems and handheld devices to the largest mainframes and supercomputers.
Since the early 1970s, the increase in processing capacity of evolving microprocessors has been known to generally follow Moore's Law. It suggests that the complexity of an integrated circuit, with respect to minimum component cost, doubles every 18 months. In the late 1990s, heat generation , due to current leakage and other factors, emerged as a leading developmental constraint.

Embedded Operating System

An embedded operating system is an operating system for embedded computer systems. These operating systems are designed to be very compact and efficient, forsaking many functions that non-embedded computer operating systems provide, and which may not be used by the specialized applications they run. They are frequently also real-time operating systems.

List of Embedded operating system:

• A/ROSE
• Embedded Linux
• QNX
• FreeBSD
• polyBSD (embedded NetBSD)
• Inferno (distributed OS originally from Bell Labs)
• ROM-DOS
• MINIX 3
• T2 SDE
• Windows XP Embedded
• Windows CE
• .NET Micro Framework
• OS/RT
• Open AT OS

Embedded System

An embedded system is a special-purpose computer system designed to perform one or a few dedicated functions, often with real-time computing constraints. It is usually embedded as part of a complete device including hardware and mechanical parts. In contrast, a general-purpose computer, such as a personal computer, can do many different tasks depending on programming. Embedded systems control many of the common devices in use today.
Since the embedded system is dedicated to specific tasks, design engineers can optimize it, reducing the size and cost of the product, or increasing the reliability and performance. Some embedded systems are mass-produced, benefiting from economies of scale.
Physically, embedded systems range from portable devices such as digital watches and MP3 players, to large stationary installations like traffic lights, factory controllers, or the systems controlling nuclear power plants. Complexity varies from low, with a single microcontroller chip, to very high with multiple units, peripherals and networks mounted inside a large chassis or enclosure.
In general, "embedded system" is not an exactly defined term, as many systems have some element of programmability. For example, Handheld computers share some elements with embedded systems such as the operating systems and microprocessors which power them but are not truly embedded systems, because they allow different applications to be loaded and peripherals to be connected.

Software Testing

Software testing is the process used to assess the quality of computer software. Software testing is an empirical technical investigation conducted to provide stakeholders with information about the quality of the product or service under test , with respect to the context in which it is intended to operate. This includes, but is not limited to, the process of executing a program or application with the intent of finding software bugs. Quality is not an absolute; it is value to some person. With that in mind, testing can never completely establish the correctness of arbitrary computer software; testing furnishes a criticism or comparison that compares the state and behaviour of the product against a specification. An important point is that software testing should be distinguished from the separate discipline of Software Quality Assurance (S.Q.A.), which encompasses all business process areas, not just testing.

Over its existence, computer software has continued to grow in complexity and size. Every software product has a target audience. For example, a video game software has its audience completely different from banking software. Therefore, when an organization develops or otherwise invests in a software product, it presumably must assess whether the software product will be acceptable to its end users, its target audience, its purchasers, and other stakeholders. Software testing is the process of attempting to make this assessment.

Software Development

Software development is the translation of a user need or marketing goal into a software product. Software development is sometimes understood to encompass the processes of software engineering combined with the research and goals of software marketing to develop computer software products. This is in contrast to marketing software, which may or may not involve new product development.
It is often difficult to isolate whether engineering or marketing is more responsible for the success or failure of a software product to satisfy customer expectations. This is why it is important to understand both processes and/or facilitate collaboration between both engineering and marketing in the total software development process. Engineering and marketing concerns are often balanced in the role of a project manager that may or may not use that title.
Marketing involvement is also known as software requirements analysis. Because software development may involve compromising or going beyond what is required by the client, a software development project may stray into processes not usually associated with engineering such as market research, human resources, risk management, intellectual property, budgeting, crisis management, etc. These processes may also cause the role of business development to overlap with software development.

How Software Operates

Computer software has to be "loaded" into the computer's storage (such as a hard drive, memory, or RAM). 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.
Instructions may be performed sequentially, conditionally, or iteratively.

• Sequential instructions are those operations that are performed one after another.
• Conditional instructions are performed such that different sets of instructions execute depending on the value(s) of some data. In some languages this is known as an "if" statement.
• Iterative instructions are performed repetitively and may depend on some data value. This is sometimes called a "loop." Often, one instruction may "call" another set of instructions that are defined in some other program or module. When more than one computer processor is used, instructions may be executed simultaneously.

Computer Software

Computer software is a general term used to describe a collection of computer programs, procedures and documentation that perform some tasks on a computer system. The term includes "application software" such as "word processors" which perform productive tasks for users, "system software" such as "operating systems", which interface with hardware to provide the necessary services for "application software", and middleware which controls and co-ordinates distributed systems.

Types of Software:

Application software allows end users to accomplish one or more specific (non-computer related) tasks. Typical applications include industrial automation, business software, educational software, medical software, databases, and computer games.

System software helps run the computer hardware and computer system. It includes operating systems, device drivers, diagnostic tools, servers, windowing systems etc

Programming software usually provides tools to assist a programmer in writing computer programs and software using different programming languages in a more convenient way. The tools include text editors, compilers, interpreters, linkers, debuggers, and so on.

Programming Language

A programming language is an artificial language that can be used to control the behavior of a machine, particularly a computer. Programming languages are defined by syntactic and semantic rules which describe their structure and meaning respectively. Many programming languages have some form of written specification of their syntax and semantics; some are defined only by an official implementation. Programming languages are used to facilitate communication about the task of organizing and manipulating information, and to express algorithms precisely. Some authors restrict the term "programming language" to those languages that can express all possible algorithms; sometimes the term "computer language" is used for more limited artificial languages. Thousands of different programming languages have been created, and new languages are created every year.

Source Code

In computer science, source code (commonly just source or code) is any sequence of statements or declarations written in some human-readable computer programming language. The source code which constitutes a program is usually held in one or more text files, sometimes stored in databases as stored procedures and may also appear as code snippets printed in books or other media. A large collection of source code files may be organized into a directory tree, in which case it may also be known as a source tree. A computer program's source code is the collection of files needed to convert from human-readable form to some kind of computer-executable form. The source code may be converted into an executable file by a compiler, or executed on the fly from the human readable form with the aid of an interpreter. The code base of a programming project is the larger collection of all the source code of all the computer programs which make up the project.