Maxtor 4320 manual Glossary, Access Time

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GLOSSARY

Glossary

A

ACCESS

Toobtaindatafrom,orplacedatainto,RAM,aregister,ordatastoragedevice.

ACCESS TIME

Theintervalbetweentheissuingofanaccesscommandandtheinstantthatthetarget datamaybereadorwritten.Accesstimeincludesseektime,latencyandcontroller overheadtime.

ADDRESS

Anumber,generallybinary,distinguishingaspecificmemberofanorderedsetof locations.Indiskengineering,theaddressmayconsistofdrives(unitaddress),radial positions(cylinderaddress),orcircumferentialposition(sectoraddress).

ALLOCATION

Aprocessofassigningdesignatedareasofthedisktoparticularfiles.

ALTERNATE TRACK

Asparetrackusedintheeventthatanormaltrackbecomesdamagedorisunusable.

ANALOG

Asignalorsystemthatdoesnotusedigitalstatestoconveyinformation.Asignalmay haveanynumberofsignificantstates(values),contrastedtodigitalsignalswhichcan onlyhavetwostates.

ANSI

AmericanNationalStandardsInstitute.

APPLICATION PROGRAM

Asequenceofprogrammedinstructionsthattellthecomputerhowtoperformsome end-usertask,suchasaccountingorwordprocessing.

AREAL DENSITY

Bitdensity(bitsperinch)multipliedbytrackdensity(tracksperinch)orbitspersquare inch.

ASYMMETRY

Adistortionofthereadbacksignalwhichisshownindifferentintervalsbetweenthe positiveandnegativevoltagepeaks.

AUXILIARY MEMORY

Memoryotherthanmainmemory;generallyamass-storagesubsystemcontainingdisk drivesandbackuptapedrives,controller(s)andbuffermemory(alsocalledperipheral memory).

AVERAGE ACCESS TIME

Theaveragetimetomakeallpossiblelengthaccesses(seeks).

AVERAGE SEEK TIME

Theaveragetimetomakeallpossiblelengthseeks.Atypicalmeasureofperformance.

B

BAD BLOCK

Ablockthatcannotstoredatabecauseofamediaflaw.

BIT

Anabbreviationforbinarydigit,ofwhichtherearetwo(0and1).Abitisthebasic dataunitofmostdigitalcomputers.Abitisusuallypartofadatabyteorword,butbits maybeusedsinglytocontrolorreadlogic“on-off”functions.Thefundamentalunit information,oftenusedlooselytorefertoacircuitormagnetizationstateataparticular instantintime.

BIOS

AcronymforBasicInput/OutputSystem.ThefirmwareareaofaCPUthatcontrols operationsthroughthesystembusandtotheattachedcardsandperipheraldevices.

BPI

Acronymforbitsperinch.Seebitdensity.

BLOCK

Agroupofbyteshandled,stored,andaccessedasalogicaldataunit,suchasan individualfilerecord.

BUFFER

Atemporarydatastorageareathatcompensatesforadifferenceindatatransferrates and/ordataprocessingratesbetweensenderandreceiver.

BUS

Acollectionoffunctionallyparallelconductorsthatformsaninterconnectionbetween functionalblocksinadigitaldevice.Alengthofparallelconductorsthatformsamajor interconnectionroutebetweenthecomputersystemCPU(centralprocessingunit)and itsperipheralsubsystems. Dependingonitsdesign,abusmaycarrydata,addresses, power,andmore.

BYTE

Anorderedcollectionofbitstreatedasaunit.Mostoften,abyteisunderstoodto consistofeightbits.Onebyteisnecessarytodefineanalphanumericcharacter.

C

CACHE

Randomaccessmemory(RAM)usedasabufferbetweentheCPUandthediskdrive.

CAPACITY

Theamountofdata,usuallyexpressedinbytes,whichcanbestoredinagivendevice orportionofsame.

CENTRAL PROCESSING UNIT (CPU) Theheartofthecomputersystemthatexecutesprogrammedinstructions.Itincludes thearithmeticlogicunit(ALU)forperformingallmathandlogicoperations,acontrol sectionforinterpretingandexecutinginstructions,internalmemoryfortemporary storageofprogramvariablesandotherfunctions.

CHANNEL

Acollectionofelectroniccircuitsusedintheprocessofwritingandreading informationtoandfrommagneticmedia.

CHARACTER

Anorderedcollectionofbitsrepresentingoneofasetofpredefinedsymbols.Oftenthe termisusedinterchangeablywithbyte,butthisisinexact.

CLOSED LOOP

Acontroltechniquethatenablesthepositioningsystemtocorrectoff-trackerrorsin realtime.Theactualheadpositionismonitoredandcomparedtotheidealtrack positiontodetermineanypositionerrorthatmightbeoccurring.Thisinformationis thenusedtoproduceacorrectionsignal(feedback)thatgoestothepositionertocorrect theerror.(Seealsotrackfollowingservo).

CLOSED LOOP SERVO

Aservocontroltechniquethatusespositionfeedbacktocorrectoff-trackerrors.See TrackFollowingServo.

CLUSTER

ThesmallestallocatableunitofdiskstorageallowedbyMS-DOS;eachFATentry representsonecluster.

CONTROLLER

Anelectronicdeviceforconnectingoneormoremassstorageperipherals(rigiddisk drives,tapedrives,andopticaldiskdrives)totheinput/outputcircuitsofahost computer.Controllersvaryincomplexity,withmoresophisticatedunitsabletobuffer andschedulecommands,correctdataerrors,andbypassmediadefectswithouthost intervention.

CONTROLLER

AminiatureCPUdedicatedtocontrollingaperipheraldevice,suchasadiskdrive, tapedrive,videodisplayterminal,orprinter.Thecontrollerexecutescommandsfrom thecentralprocessingunitandreissuescommandstotheperipheraldevice.

CORRECTABLE ERROR

AnerrorthatcanbeovercomebytheuseofErrorDetectionandCorrection.

GL – 1

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Contents HA RD Drive Produc T MA Nual DiamondMax Revisions Manual No U T I O N Before You BeginContents Handling and Installation Product SpecificationsHost Software Interface AT Interface DescriptionGlossary Interface CommandsService and Support Figures Maxtor Corporation IntroductionManual Organization AbbreviationsConventions Signal ConventionsKey Words NumberingProduct Description DiamondMax 4320 Key FeaturesFunctional / Interface Product FeaturesLogical Block Addressing On-the-Fly Hardware Error Correction Code ECCDefect Management Zone DMZ Software ECC CorrectionCache Management Read-Ahead ModeBuffer Segmentation Automatic Write Reallocation AWRMajor HDA Components Jumper Location/Configuration Subsystem ConfigurationCylinder Limitation Dual Drive SupportDrive Configuration Product SpecificationsPerformance Specifications Models and CapacitiesParameter Standard Metric Physical DimensionsPower Mode Definitions Power Requirements AverageEPA Energy Star Compliance Environmental LimitsShock and Vibration Reliability SpecificationsCanadian Emissions Statement Safety Regulatory ComplianceRadiated Electromagnetic Field Emissions EMC Compliance Hard Drive Handling Precautions Handling and InstallationPre-formatted Drive Important NoticeMulti-pack Shipping Container Unpacking and InspectionRepacking Physical InstallationRecommended Mounting Configuration Before You Begin General Requirements Mounting Drive in System Attaching Interface Power Cables System Setup Hard Drive Preparation System Hangs During Boot AT Interface Description Interface ConnectorPin Description Summary PINPin Description Table PIN Name Signal Name Signal DescriptionPIO Timing Timing Parameters ModeDMA Timing Ultra DMA Timing Mode MIN MAXSustained Ultra DMA Data In Burst Device Terminating an Ultra DMA Data In Burst Initiating an Ultra DMA Data Out Burst Device Pausing an Ultra DMA Data Out Burst Device Terminating an Ultra DMA Data Out Burst Features Register Error RegisterHost Software Interface Task File RegistersSector Number Register Sector Count RegisterCylinder Number Registers Device/Head RegisterCommand Register Summary Command Name Command Code Parameters UsedTimer Value TIME-OUT Period Alternate Status Register Control Diagnostic RegistersDevice Control Register Digital Input RegisterInterrupt Handling Reset and Interrupt HandlingReset Handling Set Feature Commands Interface CommandsRead Verify Sectors Read CommandsRead Sectors Read Multiple Read DMASet Multiple Mode Write CommandsWrite Sectors Write Verify SectorsWrite DMA Write MultipleValue Description Set Feature CommandsSet Features Mode Power Mode Commands Sleep Mode Identify Drive Initialization CommandsWord Content Description 15-8 = PIO data transfer mode = Write Cache enabled Initialize Drive Parameters Execute Drive Diagnostic Seek, Format and Diagnostic CommandsError Code Description Format Track Execute S.M.A.R.T A.R.T. Command SetService Policy Service and SupportNo Quibble Service SupportInternet MaxFax ServiceCustomer Service Glossary Access TimeCylinder Zero Gigabyte GB Logical Block Addressing Read Gate Signal THIN-FILM Media
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