Cơ sở dữ liệu - Chapter 3: Computer hardware

Chapter 3Computer HardwareLearning ObjectivesUnderstand the history and evolution of computer hardware.Identify the major types and uses of microcomputer, midrange, and maiframe computer systems.Outline the major technologies and uses of computer peripherals for input, output, and storage.Learning ObjectivesIdentify and give examples of the components and functions of a computer system.Identify the computer systems and peripherals you would acquire or recommend for a business of your choice, and explain the reasons for your selections.Section 1Computer Systems: End user and Enterprise ComputingI. Introduction All computers are systems of Input, Processing, Storage, Output, and Control ComponentsVI. Technical Note: The Computer System ConceptUnderstanding the computer as a system is of vital importanceThe Computer is MORE than a collection of electronic devices:Input – convert data into electronic form for entry into the systemProcessing – the CPU (Central Processing Unit) consists of the Arithmetic-Logic Unit (ALU – performs the arithmetic and logic functions) and the Control Unit (controls the rest of the computer)VI. Technical Note: The Computer System ConceptVII. Moore’s LawMoore’s Law 1965 – the number of transistors on a chip will double every 18-24 months; more broadly interpreted – the power or speed of a computer will double every 18-24 monthsThe Price would halve in that same time, which has also proven to be trueRecent statistics indicate this time has decreased to 12 monthsSection 2Computer Peripherals: Input, Output, and Storage TechnologiesI. PeripheralsPeripheral - a generic name for all input, output, and secondary storage devices not part of the CPU but part of the systemOnline – electronically connected to and controlled by the CPUOffline – separate from and not controlled by the CPUII. Input technologiesSource Document – the original record of the data, very important for auditing purposes; now accepted in both electronic or physical formGraphical User Interface (GUI) – presents icons, buttons, windows, etc. for use with Pointing Devices (as opposed to a text-based interface)IV. Storage Tradeoffs Tradeoffs are Cost vs. speed vs. capacity, but all regularly increase in speed, cost and capacityPrimary Storage (Random Access Memory or RAM) – Semiconductor memory, Volatile; faster but more expensiveSecondary Storage – Magnetic Disks, Optical Disks, Magnetic Tape; Non-Volatile; slower but cheaperIV. Storage Tradeoffs Direct and Sequential AccessDirect Access – Random Access Memory (RAM) and Direct Access Storage Devices (DASD) – Direct Access and Random Access are the same concept; locate an address on the storage device and go directly to that location for access to the datumSequential Access – All tape devices are accessed serially – device must be read one record at a time from the first stored datum until the desired datum is locatedV. Semiconductor MemoryRAM (Random Access Memory) – volatile, may be read and over-writtenROM (Read Only Memory) – non-volatile, may be read but not over-written or erased; PROM and EPROM may be reprogrammedFlash (Jump) Drives – solid-state memoryVII. Radio Frequency Identification (RFID) RFID – for tagging and identifying mobile objects (store merchandise, postal objects, sometimes living organisms); provides information to a reader when requestedPassive – no power source, derives power from the reader signalActive – self-powered, do not need to be close to the readerRFID Privacy Issues – may be used as spychips; gathers sensitive information about an individual without consent