 | Management Information Systems 4/e - James A. O'Brien | |||||
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Chapter 4: Managerial Overview: Computer Hardware
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Arithmetic-Logic Unit
The unit of a computing system containing the circuits that perform arithmetic and logical operations. Binary Representation Pertaining to the presence or absence of electronic or magnetic "signals' in the computer's circuitry or in the media it uses. There are only two possible states or conditions - presence or absence. Central Processing Unit (CPU) The unit of a computer system that includes the circuits that control the interpretation and execution of instructions. In many computer systems the CPU includes the arithmetic-logic unit the control unit and primary storage unit. Computer System Computer hardware as a system of input processing output storage and control components. Thus a computer system consists of input and output devices primary and secondary storage devices the central processing unit the control unit within the CPU and other peripheral devices. Computer Terminals Any input/output device connected by telecommunications links to a computer. Control Unit A subunit of the central processing unit that controls and directs the operations of the computer system. The control unit retrieves computer instructions in proper sequence interprets each instruction and then directs the other parts of the computer system in their implementation. Digital Cameras Digital still cameras and digital video cameras enable you to shoot store and download still photos or full motion video with audio in your PC. Direct Access A method of storage where each storage position has a unique address and can be individually accessed in approximately the same period of time without having to search through other storage positions. Downsizing Downsizing computer platforms results from using networks of microcomputers to replace minicomputers and mainframes. Generations of Computing Reflect stages in the development of electronic computers characterized by major changes in technology or performance. Liquid Crystal Displays (LCD) Electronic visual displays that form characters by applying an electrical charge to selected silicon crystals. Local Area Network A communications network that typically connects computers terminals and other computerized devices within a limited physical area such as an office building manufacturing plant or other worksite. Magnetic Disk Storage Data storage technology that uses magnetized sports on metal or plastic disks. Magnetic Disk Storage A small plastic disk coated with iron oxide that resembles a Floppy Disk small phonograph record enclosed in a protective envelope. It is a widely used form of magnetic disk media that provides a direct access storage capability for microcomputer systems. Magnetic Disk Storage Secondary storage medium; generally nonremovable disks Hard Disk made out of metal and covered with a magnetic recording surface. It holds data in the form of magnetized sports. Magnetic Ink Character The machine recognition of characters printed with Recognition (MICR) magnetic ink. Primarily used for check processing by the banking industry. Magnetic Tape A plastic tape with a magnetic surface on which data can be stored by selective magnetization of portions of the surface. Mainframe Computer A larger-size computer system typically with a separate central processing unit as distinguished from microcomputer and minicomputer systems. Microcomputer A very small computer ranging in size from a "Computer on a chip" to a small typewriter-size unit. Microprocessor A semi-conductor chip with circuitry for processing data. Midrange Computer Are larger and more powerful than most microcomputers but are smaller and less powerful than most large mainframe computer systems. Minicomputer A small electronic general-purpose computer. Multimedia Computer Refers to technology that presents information in more than Systems one medium including text graphics animation video sound effects music and voice. Multiple Processors Refers to computers with more than one major processing element. Networked Computer Multiple computer systems connected via telecommunications networks. Network Server Are computers that are more powerful than microcomputers. They are used to coordinate telecommunications and resource sharing in local area networks of interconnected microcomputers and other computer system devices. Offline Pertaining to equipment or devices not under control of the central processing unit. Online Pertaining to equipment or devices under control of the central processing unit. Optical Character Recognition The machine identification of printed characters through (OCR)the use of light-sensitive devices. Optical Disk Storage Technology based on using a laser to read tiny spots on a plastic disk. The disks are currently capable of storing billions of characters of information. Optical Disk Storage: An optical disk technology for microcomputers featuring CD-ROM compact disks with a storage capacity of over 500 megabytes. CD-R Compact disk recordable (CD-R) enables computers with CD-R disk drive units to record their own data once on a CD then be able to read the data indefinitely. CD-RW Compact disk rewritable (CD-RW) enables computers with CD-RW disk drive units to record and erase data by using a laser to heat a microscopic point on the disk's surface. DVD Digital video disk or digital versatile disk (DVD) enables computers with DVD disk drive units hold from 3.0 to 8.5 gibabytes of multimedia data on each side of a compact disk. Optical Disk Storage: Optical disk that allows users to write once read many WORM Disk times. Optical Scanning Using a device (scanner) that scans characters or images and generates their digital representations. Pen-Based Computing Tablet-style microcomputers that recognize hand-writing and hand drawing done by a pen-shaped device on their pressure sensitive display screens. Peripheral Devices In a computer system any unit of equipment distinct from the central processing unit that provides the system with input output or storage capabilities. Personal Digital Assistant Handheld microcomputer devices which are designed for convenient mobile communications and computing. Pointing Devices Devices which allow end users to issue commands or make choices by moving a cursor on the display screen. Pointing Device: A small device that is electronically connected to a Electronic Mouse computer and is moved by hand on a flat surface in order to move the cursor on a video screen in the same direction. Buttons on the mouse allow users to issue commands and make responses or selections. Point Device: A small buttonlike device sometimes likened to the Point Stick eraser head of a pencil. The cursor moves in the direction of the pressure you place on the track point. Point Device: Is a small rectangular touch-sensitive surface usually placed Touchpad below the keyboard. The cursor moves in the direction your finger moves on the pad. Point Device: A roller device set in a case used to move the cursor on a Trackball computer's display screen. Primary Storage Unit The main (or internal) memory of a computer. Usually in the form of semiconductor storage. Printers A device that produces hard copy output such as paper documents or reports. Secondary Storage Device External or auxiliary storage device that supplements the primary storage of a computer. Semiconductor Memory Microelectronic storage circuitry etched on tiny chips of silicon or other semiconducting material. Semiconductor Memory: Also known as main memory or primary storage; type of RAM memory that temporarily holds data and instructions needed shortly by the CPU. RAM is a volatile type of storage. Semiconductor Memory: Also known as firmware; a memory chip that permanently ROM stores instructions and data that are programmed during the chip's manufacture. Three variations on the ROM chip are PROM EPROM and EEPROM. ROM is a nonvolatile form of storage. Sequential Access A sequential method of storing and retrieving data from a file. Smart Cards Cards such as debit and credit cards which have an embedded microprocessor chip and several kilobytes of memory. Storage Capacity Elements Units used for storage capacity and data: bits bytes kilobytes (KB) megabytes (MB) gigabytes (GB) terabytes (TB). Storage Capacity Elements: A contraction of "binary digit". It can have the value of Bit either 0 or 1. Storage Capacity Elements: A sequence of adjacent binary digits operated on as a unit Byte and usually shorter than a computer word. In many computer systems a byte is a grouping of eight bits that can represent one alphabetic or special character or can be "packed" with two decimal digits. Storage Capacity Elements: When referring to computer storage capacity it is equivalent Kilobyte (K or KB) to 2 to the 10th power or 1 014 in decimal notation. Storage Capacity Elements: One million bytes. More accurately 2 to the 20th power Megabyte(MB)1 048 576 in decimal notation. Storage Capacity Elements: One billion bytes. More accurately 2 to the 30th power or Gigabyte (GB) 1 073 741 824 in decimal notation. Storage Capacity Elements: One trillion bytes. More accurately 2 to the 40th power or Terabyte (TB) 1 009 511 627 776 in decimal notation. Storage Media Trade-offs The trade-offs in cost speed and capacity of various storage media. Supercomputer A special category of large computer systems that are the most powerful available. They are designed to solve massive computational problems. Time Elements Units used for measuring processing speeds: milliseconds microseconds nanoseconds picoseconds. Time Elements: Millisecond A thousandth of a second. Time Elements: Microsecond A millionth of a second. Time Elements: Nanosecond One billionth of a second. Time Elements: Picosecond One trillionth of a second. Touch-Sensitive Screen An input device that accepts data input by the placement of a finger on or close to the CRT screen. Trends in Computers Smaller faster and cheaper. Video Input/Output Video input can serve as input as well as output. Video displays are the most common type of computer output. Voice Recognition Direct conversion of spoken data into electronic form suitable for entry into a computer system. Also called voice data entry. Voice Response Output that emerges as spoken words rather than as a visual display. Volatility Memory (such as electronic semiconductor memory) that loses its contents when electrical power is interrupted. Wand A handheld optical character recognition device used for data entry by many transaction terminals. Workstation A computer terminal or micro or mini computer system designed to support the work of one person. Also a high-powered computer to support the work of professionals in engineering science and other areas that require executive computing power and graphics capabilities. |
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