Преглед
Harddiskdrive(HDD)referstoadevicethatcontrolsharddiskaddressingandaccessingdatainapersonalcomputer.Throughtheharddrive,thecomputercanstoredata.Althoughharddiskdriveandharddiskaretwoconcepts,sincethetwoareusuallypackagedtogether,bothharddiskandharddiskusuallyrefertothedeviceformedbythecombinationofthetwo.
Състав
Themechanicalharddiskismainlycomposedofamagneticheadandamagneticdisk.Themagneticheadisthekeypartofthemechanicalharddisktoreadandwritedata.Whenthemechanicalharddiskisworking,theheadwillwritetrackdataorreadexistingdatawhilethediskisspinning.
Как работи
TheharddisksusedinearlydesktopcomputersusedIDEinterfaces.IDEinterfaceharddisksarecheapbutcost-effective;mostpersonalcomputersuseSATAinterfacesorSCSIinterfaces.TheadvantageoftheSCSIinterfaceharddiskisthatuptosevendifferentdevicescanbeconnectedtothesamecontrollerpanel.Sincetheharddiskrotatesataconstanthighspeedof3000-15000revolutionsperminute,itonlytakesashorttimetoreaddatafromtheharddisk.
Първият твърд диск в света
Първият твърд диск в светаisIBM’sSystem305,producedin1956,usedforRAMACrandomcalculationandcontrolledaccessmethodtostoredata.Theentireharddriverequires50platterswithadiameterof24inchesandthesurfaceiscoatedwithmagneticpulp.Thecapacityofthisharddriveisonly5MB.
Предпазни мерки
Ifthesolidstatedriveispoweredoff,itmaycausethecurrenttodisturbthemaincontrol,whichwillcausethemaincontroltogodown.Therefore,userswhousesolid-stateharddrives,pleasedonotcutoffthepowercasually.Althoughsolid-stateharddrivesareseveralordersofmagnitudelesslikelytobedamagedthanmechanicalharddrivesinprinciple,theystillcannotwithstandman-madefailures.