How Software Works

Overview

• Machine Language
• High Level Language
• Instructions
• Compiled Language, Compiler
• Interpreter, Interpreted Language
• Object Program
• Source Program
• Linking
• Application software
• System software

The microprocessor only understands machine language- the instructions set that is hard wired with in the microprocessors circuit. Therefor instructions written in high level language (English like language, example:- C, C++, Visual Basic, Java etc..) must be translated into machine language (consists of only 0 and 1) before a computer can use them. Figure below gives an idea of what happens to a high-level instruction when it is converted into a machine language instruction.

A program can be translated into machine language in two ways. When each statement in the source program is translated individually and executed immediately, the programming language is called an interpreted language, and the program doing the translation is called an interpreter.

A compiler translates all the instructions in a program before anyone statement is executed. The program doing the translation is called a compiler and the programming language is called compiled language. The machine language version of the original source program is called the Object program. An object program is simply a translated version of the source program that can be executed by the computer system with one more processing step, called Linking.

Most programs contains statements that use preprogrammed routines, called library functions, for finding such quantities as logarithms, square roots, trigonometric values, absolute values, or other commonly encountered mathematical calculations. Additionally, a large C program may be stored In two or more separate program files. However, multiple files must ultimately be combined to form a single program before the program can be executed. In both of these cases it is the task of the linker to combine all of the intrinsic functions and individual object files into a single program ready for execution. This final program is called an executable program. For ease of operation, all operating system that provide a C compiler also provide a single command that both compiles a C program and links it correctly with any other required object programs using one command.

Software is categorized as application software or system software. Software used for creating documents, crunching numbers, drawing designs, and editing photographs are categorized as Application Software. Primary purpose of application software is to help people carry out tasks using a computer.

Other category is System software, which includes your computers operating system, device drivers, and utilities. The primary purpose of System software is to help the computer carry out its basic operating functions.

Other relavent topics

• What is inside a computer?
• Operating system
• Programing Language
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• Unix tutorial

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