Storage Devices Terms

S T U D E N T S W I L L B E A B L E T O :

•U S E T E R M S A S S O C I A T E D W I T H S T O R A G ED E V I C E S ;

Objective

S T U D E N T S W I L L B E A B L E T O :

•U S E T E R M S A S S O C I A T E D W I T H S T O R A G ED E V I C E S ;

Disk read/write head

• A device that reads(senses) and writes(records) data on amagnetic disk or tape

• Move above the diskplatter and transformplatter’s magnetic fieldinto electrical current(read the disk)

• Transform electricalcurrent into magneticfield (write the disk)

• A device that reads(senses) and writes(records) data on amagnetic disk or tape

• Move above the diskplatter and transformplatter’s magnetic fieldinto electrical current(read the disk)

• Transform electricalcurrent into magneticfield (write the disk)

Tracks

• Path on tape, disk, drumon which data are stored

• On a disk these paths areconcentric circles, on atape there are parallelrows; on a drum thereare bands of equal sizealong the circumference

• Each track is numberedstarting from 0

• Path on tape, disk, drumon which data are stored

• On a disk these paths areconcentric circles, on atape there are parallelrows; on a drum thereare bands of equal sizealong the circumference

• Each track is numberedstarting from 0

Sectors

A pie shaped division ofeach disk track

Basic unit of data storageon a hard disk

diagram shows 3 disksectors highlighted

Sector A pie shaped division of

each disk track

Basic unit of data storageon a hard disk

diagram shows 3 disksectors highlighted

Diagram shows one tracksector

This is the area ofintersection of a trackand a sector

Each track sector isidentified by a uniqueaddress which identifiesevery recording location

Diagram shows one tracksector

This is the area ofintersection of a trackand a sector

Each track sector isidentified by a uniqueaddress which identifiesevery recording location

Cylinders

• refers to all data foundon the same track ofdifferent platters (i.e.above and below oneanother), as this forms a"cylinder" of data

• A parallel set of tracks ina hard drive accessiblefrom one position of theread/write head

• refers to all data foundon the same track ofdifferent platters (i.e.above and below oneanother), as this forms a"cylinder" of data

• A parallel set of tracks ina hard drive accessiblefrom one position of theread/write head

Clusters

Is a set of track sectors, ranging from 2 to 32 ormore, depending on the formatting scheme used

Buffers

Also known as disk cache or cache buffer

Immediate storage location where data istemporarily stored until it is ready to be used

Many parts of the computer operate at differentspeeds, e.g. Printer and CPU

Also known as disk cache or cache buffer

Immediate storage location where data istemporarily stored until it is ready to be used

Many parts of the computer operate at differentspeeds, e.g. Printer and CPU

• Access time: the amount of time it takes tocomplete a request for data to be retrieved fromstorage

• Sequential access: accessing data in the order inwhich it was stored.

• Direct access: accessing data by going to the exactlocation and reading only the required data

• Access time: the amount of time it takes tocomplete a request for data to be retrieved fromstorage

• Sequential access: accessing data in the order inwhich it was stored.

• Direct access: accessing data by going to the exactlocation and reading only the required data

Device interfaces(SCSI)

• Small Computer SystemsInterface (SCSI): set ofstandards for physically connecting andtransferring data between computers andperipheral devices

• SCSI standards define commands, protocols,electrical and optical interfaces

• Commonly used for hard disks and tapedrives

• Provide faster data transmission rates thanserial and parallel ports ( up to 80MB persecond)

• Can attach many devices to a single SCSIport, making it an I/O bus than simply aninterface

• Small Computer SystemsInterface (SCSI): set ofstandards for physically connecting andtransferring data between computers andperipheral devices

• SCSI standards define commands, protocols,electrical and optical interfaces

• Commonly used for hard disks and tapedrives

• Provide faster data transmission rates thanserial and parallel ports ( up to 80MB persecond)

• Can attach many devices to a single SCSIport, making it an I/O bus than simply aninterface

Integrated Drive Electronics (IDE): aninterface for mass storage devices

The controller is integrated into the disk or CD-ROM drive

Device Interface(IDE)

Integrated Drive Electronics (IDE): aninterface for mass storage devices

The controller is integrated into the disk or CD-ROM drive

Serial Advanced Technology Attachment(SATA): a computer bus primarily designed fortransfer of data between a computer and massstorage devices such as hard disks drives andoptical drives

Device Interface(SATA)

Serial Advanced Technology Attachment(SATA): a computer bus primarily designed fortransfer of data between a computer and massstorage devices such as hard disks drives andoptical drives

References

Oxford Information Technology for CXC CSEC byGlenda Gay, Ronald Blades

CXC Information Technology by Kelvin Skeete

Oxford Information Technology for CXC CSEC byGlenda Gay, Ronald Blades

CXC Information Technology by Kelvin Skeete