Computer Technology-2

COMPUTER TECHNOLOGY

M.M.Palitha Mahinda MunasingheDistrict Agricultural Training CentreHomagama -Sri LankaInput Technologies2008/04/062mmpmmNatural user interface Enter data and commands directly into a computerElectronic mice and touch padsOptical scanning, handwriting recognition, voice recognition

Pointing Devices2008/04/063mmpmmUsed for entering data and textWork with your operating systems graphical user interface (GUI)Electronic mouseTrackballPointing stickTouch padTouch screen

Pen-Based Computing2008/04/064mmpmm

Used in many hand-held computers and PDAs

Graphics tablet Digitizer pen

Speech Recognition Systems2008/04/065mmpmmDigitize, analyze, and classify your speech and its sound patternsAllow operators to perform data entry without using their hands to key in data or instructionsSpeaker-independentVoice-messaging computers

Optical Scanning2008/04/066mmpmmRead text or graphics and convert them into digital inputEmploy photoelectric devices to scan the characters being read

Optical character recognition (OCR) Reads OCR characters & codes Merchandise tags Product labels Sort mail, score testsHand-held optical scanning wandsReads bar codingUniversal Product Code (UPC)

Optical Scanning 2008/04/067mmpmm

Other Input Technologies2008/04/068mmpmmMagnetic stripe technologyCredit cards

Smart cards Embedded microprocessor chip Debit, credit, and other cards

Digital camerasStill camerasDigital camcorders

Other Input Technologies 2008/04/069mmpmmMagnetic ink character recognition (MICR) technologyUsed by banks to sort and post checks and deposit slips14 characters of a standardized designReader-sortersVideoPrintStorage

Video Output

2008/04/0610mmpmmVideo monitors Cathode ray tube (CRT)Liquid crystal displays (LCDs)

Inkjet PrintersSpray ink onto the page one line at a time

Laser PrintersUse an electrostatic process similar to a copier

Printed Output

2008/04/0611mmpmm2008/04/0612mmpmmLaser Printers Components

Storage Trade-Offs

2008/04/0613mmpmmInformation is stored through the presence or absence of electronic or magnetic signalsBinary representation 1 = ON 0 = OFF

2008/04/0614mmpmmComputer storage2008/04/0615mmpmmBitThe smallest element of dataMay have a value of either one or zeroByteBasic grouping of bitsTypically, a byte consists of 8 bits and represents one character of dataComputer storageComputer storage fundamentalsStorage capacitiesKilobytes (KB) = 1,000 bytesMegabytes (MB) =1 million bytes

2008/04/0616mmpmmComputer storage2008/04/0617mmpmmComputer storageComputer storage fundamentals Gigabytes (GB) = 1 billion bytes Terabytes (TB) = 1 trillion bytes Petabyte (PB) = 1 quadrillion bytes2008/04/0618mmpmmDirect and sequential accessTerms direct access and random access describe the same conceptAn element of data or instructions can be directly stored and retrieved by selecting and using any of the locations on the storage mediaEach storage positionHas a unique addressCan be individually accessed in approximately the same time

Computer storage2008/04/0619mmpmmSequential accessDoes not have unique storage addressesSerial processData are recorded one after another in a predetermined sequenceLocating an individual item requires searching all of the data until the desired item is locatedComputer storage2008/04/0620mmpmm

Computer storageSemiconductor Memory2008/04/0621mmpmmPrimary storage of your computerAdvantagesSmall sizeGreat speedShock and temperature resistantDisadvantageVolatilitySemiconductor Memory 2008/04/0622mmpmmTwo basic types of semiconductor memory

RAM random access memoryVolatile memoryRead/write memoryworking memory

Semiconductor Memory2008/04/0623mmpmmROM read only memoryNonvolatileUsed for permanent storageCan be read but not erased or overwritten

Variations of ROMPROMProgrammable read only memoryEPROMErasable programmable read only memoryMagnetic Disk Storage2008/04/0624mmpmmMost common form of secondary storageData is recorded on tracks in the form of tiny magnetized spotsThousands of bytes recorded on each track

Magnetic Disk Storage

2008/04/0625mmpmmTypes of Magnetic DisksFloppy disks

Zip disks

Hard disk drives

Magnetic Disk Storage 2008/04/0626mmpmm Redundant arrays of independent disks (RAID)Provides large capacities with high access speedsData are accessed in parallel over multiple paths from many disksFault tolerantStorage area networks (SANs)Fiber channel LANs that connect many RAID units

Magnetic Tape Storage2008/04/0627mmpmmUsed as secondary storageAlso used in robotic automated drive assembliesLower-cost storageArchival storage

Optical Disk Storage

2008/04/0628mmpmmCD-ROMCD-RCD-RW

DVDDVD-ROMDVD-RW

Optical Disk Storage 2008/04/0629mmpmmBusiness applicationsImage processingProvide access to reference materials in a convenient, compact formvideos