A PRESENTATION ON COMPUTER DATA STORAGE -

PRIMARY & SECONDARY MEMORY

By Ayush Garg

1. Primary Memory2. Secondary Memory3. Summary4. Questions & Answers5. Thank You

Flow of the Presentation

Primary Memory…1. Only one directly accessible to the CPU.2. Used to hold the temporarily data during the

execution.3. Other names are – Main Memory or Internal

Memory4. Types of Primary memory–

1. RAM – Random Access Memory2. ROM – Read Only Memory3. PROM/EPROM - Programmable ROM

5. It has a Limited Capacity6. Information is retained only when it is Actively

Rehearsed.

Primary Memory…

EPROM

ROM

RAM

sSecondary Memory . . .

1. Secondary Memory also known as EXTERNAL MEMORY or AUXILIARY MEMORY.

2. Often formatted according to a File Systems Format.

3. Provide abstraction necessary to organize data into files and directories.

4. Also Providing Additional Information METADATA describing the owner of the certain file.

Random Access Storage Devices

Allows Stored Data to Be Accessed Quickly In Any Random OrderIt Has Taken The Form Of Integrated Circuits It is Associated With Volatile Types Of Memory Where The Stored Data Is LOST If The Power Is REMOVED Any Location In The Device Can Be Selected At Random, Access To The Information Stored Is DIRECT

A Class Of Data Storage Device It Reads the Data In Sequence Very Much In Contrast With RAM (where Data Can Be Accessed In Any Order) They Are Usually A Form Of Magnetic Devices Access Can STILL Be Made To Arbitrary Locations Typically Used For Secondary Storage It Has High Density And Cost As Compared To RAM As Well As Resistance to Wear and Non-Volatility EXAMPLE – Hard Disks, CD- ROMS And Magnetic Tapes

Sequential Access Storage Devices

HARD DISKS

PERFORMANCE ENHANCEMENTS

OPTICAL DISKS

SPECIALISED MEDIA

FLOPPY DISKS

Types Of SASD

Portable And Removable

Flat Circular Mylar Media

Magnetic Charge on Metal Oxide Film Coating

Standard 2 HD 1.44 MB

Parts

Tracks Sectors

Floppy Disks

Floppy disk cartridgesZip Disks

250 MBSuper Disks

120 MBHiFD disks

200 MB

High Capacity Floppy Disks

Metallic disksFast retrieval, greater capacityRead/write heads ride cushion of

air .000001” thickThree types

Internal hard diskHard-disk cartridgeHard-disk pack

Hard Disks

No Entry

Inside system unitNon-removable or portableGreat capacity

Over 100 GigabytesFast access speed

Internal Hard Disks

HARD DISK CARTRIDGESPortable,

removableComplement

internal hard driveJAZ from Iomega SPARQ from

SyQuestPC Card Hard

DisksLaptop

computers

HARD DISK PACKSUsed in mainframesRemovable

Resemble stack of vinyl records

Multiple read/write heads

Massive storage capacity

Fast access time

Performance Enhancements

Improving performance of hard disksDisk caching Redundant Arrays of Inexpensive Disks

(RAID)File compression and decompression

Very large capacityUp to 17 gigabytes

Use reflected light projected by a laser

Lands and Pits represent 1’s and 0’s

FormatsCompact Disk (CD)Digital Versatile

Disk (DVD)Data Play

Optical Disks

Widely used format today

Can store from 650 MB to 1 GB

Rotational speed = data transfer time

Types of CDsCD-ROMCD-RCD-RW

Compact Disks

Digital Versatile Disk

Rapidly replacing CDs Higher capacity17 times the

capacity of a CD

DVD

DVD typesDVD-ROM

Read only memoryDVD-R

RecordableDVD-RAM or DVD-RW

Competing rewritable formats

DVD Types

DATA PLAYOptical write-once

formatSimilar to CD-RSize of a quarterUsed for special

applicationsStoring digital

photographsStoring music for

portable players

MAGNETIC TAPESequential accessCommonly used for backing-up

dataVery large capacityTypes of magnetic tape

Tape cartridgesMagnetic tape reels

Tape cartridgesBackup tape for microcomputer Capacities range from 120 MB to 5

GBDigital audio tape (DAT)

Tape reelsMinicomputer and mainframe1/2 inch wide and 1/2 mile longStores 1600 to 6400 cpi

Internet hard driveFree or low-cost storage on the WebAccess information from any locationAccess time is greater

Solid-state storageNo moving partsFlash memory cards

Internet Hard Drives &

Solid States

A Look To The FutureBlue laser light optical

devicesAimed more

accuratelyCan increase storage

capacity to 27 GB per standard optical disk

New players will likely play both

Questions & Answers

THANK YOU