PRESENTED BY:Sabin Kafle

Why secondary storage?

Non-VolatileFasterSimple, Portable, EasyMemory UnlimitedPopularityCheaper than Primary Memory

Points to Remember

Storage Devices

Disk types

• Floppy disks• Hard disks• Magnetic Tape• Zip disks• Flash drive• Optical disks ( CD-ROM, CD, DVD, RW)

Magnetic Storage Devices

Floppy Disk

low capacity only 1.44 Mb Zip as ‘Super floppies’ 100 Mb Read-write Small, light, portable Outdated

Magnetic Sorage Device

Hard Disk

Non-Volatile Faster than floppy Higher capacity terms of GB. Non-removable, Removable, most common. R-W drive 1st introduced in IBM PC Coated with magnetic material Expensive one

Magnetic Storage Device

Magnetic tape

Ribbon of plastic materialMagnetic recordingAnalogue dataRW and DurableCapacity depends upon length and sizeNot suitable for data files

Storage Device

Optical disks

CD-ROM

Non-Volatile Digital optical device laser technology, extremely fast Typical capacity of 700 Mb Store any type of data Being replaced Diameter of 120mm Thickness of 1.2mm Low quality playback than DVDs

Storage Devices

Compact Disc-RecordableWrite Once Read ManyMade of polycarbonateRetains a high level of compatibilityCheaper formRead using Laser light

CD-ROptical disk

Optical Storage Device

CD-RW

Rewritable optical discRequire a more sensitive laser opticsHardware with RW is requiredRe-Written up to 10,000 times

Recordable optical discCheaperRecords multi-formatsCapacity of 4.7GB Non-Volatile data storage

Optical Storage Device

DVD-R

Optical Storage Device

DVD-RW

Rewritable optical diskTypically 4.7GBHardware capability requiredWidely usedDiameter of 8 cm

Electronic Storage Device

Flash memory

Opto-Magnetic storageEEPROM based technologyData transferPortable, Easy, SimpleHigher speed Multiple purpose