Chapter one • Information technology (IT) – the study, design, development, implementation, support or management of computer-based information systems – deals with the use of electronic computers and computer software to convert, store, protect, process, transmit, and retrieve information • Information System (IS) – collects, processes, stores, analyzes, and disseminates information for a specific purpose • A Computer-based Information System (CBIS) – an information system that uses computer and often telecommunications technology to perform some or all of its intended tasks • E.g. Ethiopian Airlines reservation system • Dashen Bank’s banking system • Commercial bank ATM system etc What is Computer Science • a science concerned with information i.e. representation, storage, manipulation or processing and presentation • computer Science uses a special device called COMPUTER • has different fields of specialization or subdisciplines – – – – – – – – Software engineering Computer engineering (Architecture) Automata theory Database Architecture Artificial intelligence Communications Human-Computer Interaction Concurrent, parallel, and distributed systems What is a Computer • is an electronic device that accepts data, performs computations, and makes logical decisions according to instructions that have been given to it; then produces meaningful information in a form that is useful to the user • It saves time, space, money, labors Characteristics of computers • Speed – • Accuracy – • computer is accurate and consistent provided that the data and the instructions are correct Storage Capacity – • The ability of computers to store and process vast amounts Durability and reliability – • They can operate error-free over long periods of time Versatility – • The ability of the computers to carry out their instructions in a very short period of time a wide array of application Even if the above main characteristics of computers are increasing with time, the cost and size of computers are decreasing. Types of Computers • Based on the operational principle – Analog – Digital – Hybrid • Analog – operate by measuring – deal with continues variables – E.g • • Thermometer Voltmeter – Almost an extinct type of computer these days • Digital computers – deal with discrete variables – operate by counting rather than measuring – operate directly up on numbers (or digits) that represent numbers, letters, or other special symbols. – E.g. . • Desk & pocket computers • The general purpose computers – have higher accuracy and speed – on the principle of binary mathematics • Hybrid computers • combination of both Analog and Digital computers • Based on functionally – Special purpose – General purpose • Special purpose computers – computers that are designed for a specific task – E.g. ATM, • General purpose computers – computers that perform many tasks without specialization. – E.g. Desktop Computers, Laptops, etc • Based on size, capacity, speed and reliability – Micro computer – Minicomputer – Mainframe computer – Supercomputer • Microcomputer – A personal computer; designed to meet the computer needs of an individual. – Provides access to a wide variety of computing applications, such as word processing, photo editing, e-mail, and internet. • Desktop – – A microcomputer that fits on a desk and runs on power from an electrical wall outlet. – The CPU can be housed in either a vertical or a horizontal case. – Has separate components (keyboard, mouse, etc.) that are each plugged into the computer • Laptop – A portable, compact computer that can run on an electrical wall outlet or a battery unit. – All components (keyboard, mouse, etc.) are in one compact unit. – Usually more expensive than a comparable desktop. – Sometimes called a Notebook Minicomputers • are bigger in size than the Microcomputer systems • can give parallel access to up to 100 users Mainframe • Large expensive computer capable of simultaneously processing data for hundreds or thousands of users. • Used to store, manage, and process large amounts of data that need to be reliable, secure, and centralized. • maximum I/O connectivity as they accommodate huge disc farms. • occupy an entire room and could cost over million dollars they have almost become extinct Supercomputer • A computer that was the fastest in the world at the time it was constructed. • Can tackle tasks that would not be practical for other computers. – Typical uses • Breaking codes • Modeling weather systems Handheld • Also called a PDA (Personal Digital Assistant). • A computer that fits into a pocket, runs on batteries, and is used while holding the unit in your hand. • Typically used as an appointment book, address book, calculator, and notepad. • Can be synchronized with a personal microcomputer as a backup. Application of Computers • Learning Aids • Entertainment • Commercial or business applications • Scientific – engineering and research applications • Information Utilities • Electronic Banking and Service • Shopping from Home • Weather and Environment • Transportation • Medical and Health Care • Routine and dangerous Tasks • Consultant (Expert system)