Pakistan study notes for Matric, Intermediate, B.A, B.COM BSC, M.A, BCS. Free Pakistani Urdu educational school, colleges and University notes.



Software is a general term used for computer programs. A computer program is a planned, step by step of instructions that directs the computer what to do and how to do. There are two types of software, namely, System software and Application software.


System software: System software performs tasks associated with controlling and utilizing computer hardware. System software is of following types.

Operating system: Operating system is a set of program that controls and supervises the hardware of a computer and provides services to application software, programmers and users of computer.


Language translators: It translates a computer program into machine understandable form. Language translators are interpreter, compiler and Assembler. Interpreter translates and executes each program statement one at a time, translation is required if program is run again complier translates the whole program at a time and stores translated program on disk. The assembler is translator for Assembly language.


Data-management software: These software are used are organizing, updating and printing data. Editors: These software enable the user to type-in a program or generate text and make modification whenever necessary.


Utility software: These programs are used to perform a wide range of functions like virus cleaning etc.

Application software: Application software are programs that help a user to perform a specific job, and. are of two types: General-purpose and special-purpose. By using General-purpose software, a user can fulfill his general needs, e.g. MS-Office, Adobe shop etc. The software which performs only one task for which it has been designed, are termed as special-purpose software, e.g. Airline ticketing system or accounting software of a company etc.


Disk Operating System (DOS): DOS is an operating system. It manages the routine work of computer system, controlling everything from internal memory, monitor display, keyboard, input and external communication. When computer is started using DOS, the character C:\> appears on the screen [called prompt, it's an appearance can be different]. The C is drive, which can be changed by typing “drive letter”: and press the center key.

Data is stored into storage devices in the form of Filing, and DOS has naming convention for all files. Each file must have a name, which consists of two parts, the name and the extension. For example “myfile.txt”, here name is “my file”, and extension is “txt”.

While looking for particular file, wild cards can be used. “T’ can take the place of any sin le character, while *can replace any groups of characters.


DOS Commands: Command is a way of communication and used to perform specific tasks.


There are two types of commands namely, internal commands and external commands.

Internal commands are built into DOS, and loaded with DOS when computer is getting start d. These commands are immediately available in memory and con not be seen in the disk files list. The internal commands are DIR, CLS, DATE, TIME, COPY, VER, VOL, DEL, TYPE, REN, PROMPT, MD, RD, CD, PATH, etc.


External commands are stored on disk as files. DOS must read these commands from the disk before you can execute them. Some commands are FORMAT, CHKDSK, LABLE, DISKCOPY, PRINT, SYS, EDIT, XCOPY, DELTREE, DOSKEY, etc.

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