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Computer System Categories

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Microcomputer Systems

Personal Computer (PC) – microcomputer for use by an individual

Desktop – fit on an office deskLaptop – small, portable PCWorkstation – a powerful, networked PC for

business professionalsNetwork Server – more powerful

microcomputers that coordinate telecommunications and resource sharing in small networks

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Terminals

Devices that allow access to a networkDumb terminals – keyboard and video monitor

with limited processingIntelligent terminals – modified networked PCs

or network computers

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Information Appliances

Hand-held microcomputer devicesPersonal digital assistants (PDA)

BlackBerryVideo-game consolesInternet enabled cellular phones

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Midrange systems

High-end network serversMinicomputers for scientific research and

industrial process monitoring Less costly to buy, operate and maintain than

mainframe

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Mainframe Computer Systems

Large, fast powerful computer systemsLarge primary storage capacityHigh transaction processingComplex computations

Can be used as superservers for large companies

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Supercomputer Systems

Extremely powerful systemsScientific, engineering and business

applications at extremely high speedsGlobal weather forecasting, military defenseParallel processing with thousands of

microprocessorsBillions of operations per secondMillions of dollars

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Computer System hardware functions

InputConvert data into electronic form

Processing - Central Processing Unit (CPU)Arithmetic-logic unit performs the arithmetic

functionsControl unit

OutputConvert electronic information into human-

intelligible formStorage

Primary Storage Unit or MemorySecondary Storage: Magnetic disks and Optical disks

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How corporate buyers choose PCs

Solid performance at a reasonable priceOperating system readyEnough storage capacityConnectivity – reliable network

interface or wireless capability

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Storage tradeoffs

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Computer Storage FundamentalsBinary representation

Data are processed and stored in computer system through the presence (1) or absence (0) of signals

Bit (short for binary digit)Smallest element of dataEither 0 or 1

ByteGroup of eight bits which operate as a single unitRepresents one character

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Representing characters in bytes

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Measuring storage capacitiesKilobyte (KB): one thousand bytesMegabyte (MB): one million bytesGigabyte (GB): one billion bytesTerabyte (TB): one trillion bytes

Processing/Clock speed of CPU:Megahertz (MHz) – millions of cycles/instructions

per secondGigahertz (GHz) – billions of cycles/instructions

per second

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Two types of semiconductor memory

RAM: random access memoryMost widely used primary storage mediumVolatile memoryRead/write memory

ROM: read only memoryFrequently used programs burnt into chips

during manufacturingCan be read but cannot be overwrittenCalled firmware

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Radio Frequency Identification (RFID)

Tag and identify mobile objectsE.g., store merchandise, postal packages, pets

Use RFID chips to transmit and receive radio signals

Chips half the size of a grain of sandPassive chips:

do not have power source and derive power from signal in reader

Active chips: Self-powered