210 likes | 343 Views
The components of a computer (Part I). Overview : A computer. accepts data and processes it into useful information consists of input: accepts data in machine-readable form and sends it to the processor. Processor (CPU):executes computer instructions to turn the data into useful information.
E N D
Overview : A computer • accepts data and processes it into useful information • consists of • input: accepts data in machine-readable form and sends it to the processor. • Processor (CPU):executes computer instructions to turn the data into useful information. • Output:makes the machine-readable information available for users. • Storage:supplements main memory - diskettes, hard disk, CD-ROM, etc.
Main Components of a Computer Secondary Storage Input Processing Output
Input • Input devices accept data and instructions from the user • keyboard: you type in your input (the display screen is actually an output device • mouse:moves pointer on screen, pressing button invokes commands • scanners: bar code readers, flat bed scanners, etc., captures codes, photos, drawings, text into the computer directly • writing tablets:reads hand-written Chinese characters • data glove: captures gestures as well as 3D coordinates • sensors:temperature, pressure,… • card readers: one line of data/instruction per card
Processor • The central processing unit (CPU) is the brain of the computer • it transforms raw data into useful information • it executes program instructions • it consists of electronic circuits etched into silicon or other material - a chip of a set of chips plugged into circuit boards
Memory • Computer memory, or primary storage, is not part of the CPU but closely associated with it • memory holds the program and the data being processes by the CPU • while the data and program are in memory, the processor can communicate with it directly • this built-in memory is called random-access memory (RAM) • the common unit of measures is the byte-8 bits - the amount needed to store a single character (Chinese characters need more than 1 byte) • common short-hands - kilobyte (KB) and megabyte (MB)
Output • Raw data processed into useable information • 2 common devices are the display screen (monitor) and the printer • early monitors display only characters in one color, now they can display any shape or symbols in virtually any color • printers produce printed material under the control of a program
Secondary Storage • Secondary storage is where the computer stores data and programs that it is not currently using • common media : magnetic disk and magnetic tape • data in secondary storage cannot be accessed directly (unlike main memory) • but • they have larger capacity • they retain their contents even when the computer is turned off • they are much cheaper per unit
Common diskettes come in 2 sizes: 3-1/2 and 5-1/4 • hard disks have large capacity and offer faster access time then diskettes • optical disks have much higher capacity, but cannot be written on easily • magnetic tape is similar to audio/video tapes, they are inexpensive, but can only be accessed sequentially
MICROPROCESSOR • Microprocessor Comparison • Intel Pentium • Intel Celeron • AMD (Intel-compatible) • Motorola PowerPC • Alpha
MICROPROCESSOR • Microprocessor Comparison • Intel processors • Xeon • Pentium II with MMX • Celeron
MICROPROCESSOR • Processor Installation and Upgrades • Zero-insertion force (ZIF) sockets • Upgrades • Chip for chip • Piggyback • Daughterboard
MICROPROCESSOR • Coprocessors • Special processor chip or circuit board designed to assist the processor in performing specific tasks • Floating-point coprocessor
MICROPROCESSOR • Parallel Processing • Using multiple processors simultaneously to execute a program • Speeds execution • Requires special software
Classes of Computers • Mainframes - very high speeds and very large data volumes • Minicomputers - a step down • Super-minis • Personal Computers(PC) - microcomputers • Super-micros • laptops - notebooks, runs on battery • Sub-notebooks • Pen-based Computers - personal digital assistants
Communication • Computers started out very large, with many dumb terminals connected • Gradually computers become smaller and smaller, with only one set of keyboard/monitor • These PCs need to communicate with one another, as well as mainframes • Again we have many PCs (intelligent terminals) connected to mainframe, or many mainframes
A Simple Computer Network • Processing have been decentralized, or distributed • It becomes a network • By far the most important network service is electronic mail • Now the Internet is rapidly gaining in importance