Chapter 2 - Chapter 2: software The instructions and...

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Chapter 2: software The instructions and associated data that direct the computer to perform a task. For example, a word processor and its associated dictionary or thesaurus are software. A report you create using a word processor is not software (it does not contain instructions for the computer.) A specific item of software is a software package. You purchase software and by the nature of the purchase become licensed to install and use it on a single computer. Most often, you are not supposed to install the same software package on more than one computer (single-user license). Some software comes with a multiple-user license for a specified number of users, priced per user. Other software comes with a site license which enables anyone at a particular location (university campus, hospital) to use it. Public domain software is owned by the public, not the author and can be duplicated and distributed freely. Shareware is owned by a software author, but the author distributes it for free. The author hopes that users will like it enough to purchase enhanced versions. The user may become a registered user for a small fee, or for a larger fee be entitled to upgrades and newer versions as they become available. 2 Major categories of software: System software helps the computer carry out its basic operating tasks (written for the computer to enable it to perform useful operations) - operating system, language compiler, software to control a CD ROM drive (or other peripheral unit). Applications software helps computer users perform specific tasks: word processing, payroll, inventory control, playing games, education. Most important piece of system software: operating system. It acts as a liason between the hardware and the application software, performing essential tasks for the application software such as retrieving data stored in files (accessing the hard disk, determining where file data is stored and transferring file data to main memory), printing reports (controlling the flow of information from memory to the printer). The operating system is also the interface between the user and the computer hardware and other software. Some operating system functions: Controls basic input and output - controls flow of data to and from computer and peripheral devices like keyboard, screen, printer, disk drives that may be used for program input or output. Allocate system resources - Allocates processor time so that
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Chapter 2 - Chapter 2: software The instructions and...

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