Storage Devices

Secondary Storage Devices

Group Members Muhammad Waseem Saba Batool Uzma Batool Israr Ahmad Muhammad Waseem

Magnetic Tape

Magnetic Tape Magnetic Tape is the most popular storage medium that are accessed and processed sequentially.

Structure: • Magnetized recording material • Plastic ribbon • Length varies from 50-2400 ft

Basic Principle of Operation • Storage Organization • Storage Capacity • Data Transfer rate • Tape Drive • Tape Controller

Storage Organization • • • • • •

Vertical columns called frames Horizontal rows called tracks Older magnetic tape with 6 tracks BCD code format Parity bit Most modern magnetic tape with 9 tracks • EBCDIC code format • IRG (inter record gaps) • IBG (inter block gaps)

• Storage capacity Storage capacity of a tape = Data recording density x Length

• Data transfer rate Data transfer rate = Data recording density x speed

Tape

• Tape Drive Storage and retrieval of data

• Tape Controller Read/Write of information Interprets the command for operator tape drive

Storage Organization

Types of Magnetic Tapes • 1/2 –inch tape reel • 1/2-inch tape cartridge • ¼-inch streamer tape • 4mm-digital audio tape (DAT)

Half-Inch Tape Reel

Half-Inch Tape Cartridge

Quarter-Inch Streamer Tape

4mm Digital Audio Tape (DAT)

Advantages of Magnetic Tape • Storage Capacity is virtually unlimited. • Low Cost • Portability

Limitations of Magnetic Tape • No Direct Access • Slow • Environment Problem • Temperature Problem • Must be labeled

Uses of Magnetic Tape • Sequentially data processing • Back up of data • Achieving of data • Transferring of data and programs • Distribution of software by vendors

Magnetic Disk

Magnetic Disk • Magnetic disk are the most popular direct access secondary storage device. They are also the most popular online secondary storage device.

Basic Principles of Operation • • • •

Storage Organization Storage Capacity Access Mechanism Access Time i. ii. iii.

Seek Time Latency Transfer Rate

Storage Capacity

Storage Organization

SECTOR

Access Mechanism

Basic Principle of Operation • Disk Formatting • Disk Drive • Disk Controller

Types of Magnetic Disks

Floppy Disk • Floppy Disk (31/2-inch Floppy Disk)

Storage of Data in 31/2 inch Floppy • Double Density 40 tracks, 18 sectors/track, 512 bytes/sector 2 x 40 x 18 x 512 = 737280 => 720 KB

• High Density 80 tracks, 18 sectors/track, 512 bytes/sector 2 x 80 x 18 x 512 = 1474560 => 1.4 MB

• Very High Density 80 tracks, 36 sectors/track, 512 bytes/sector

Floppy Disk Drive

Hard Disk

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Hard Disk A primary online secondary storage device.

They are ridge metal (aluminum) platters comes in many sizes, range, 114 inch diameter.

Part s of Har d Disk

Types of Hard Disk

o Zip Disk

o Disk Pack

o Winchester Disk

Advantages of Magnetic Disks • • • • • • • • •

Direct Access Multiple Uses Suitable for online & offline storage of data Unlimited Storage Capacity Low Cost Light in weight & size Portable High Data Transfer Rate Less vulnerable to data corruption

Limitations of Magnetic Disks • Less efficient than magnetic tape • Security of information • Recovery of loss data • Portability • Expensive • Environment as dust free • Must be labeled

Uses of magnetic disks • • • •

Random data processing Shared on line secondary storage devices Back up for off line data storage Archiving of data that may be used occasionally • Transferring of data between two computers • Distribution of software by vendors

Composed By

Muhammad Waseem Yousaf Roll # 2053

[email protected] [email protected] [email protected] For more help u can mail me 0300-7324189