Raymond WashingtonRaymond Washington

Secondary StorageSecondary StorageChapter 8Chapter 8

Traditional Floppy DiskTraditional Floppy Disk The Traditional Floppy Disk is the 1.44 MB The Traditional Floppy Disk is the 1.44 MB

331/21/2-inch disk. They came out about 20 -inch disk. They came out about 20 years ago and still use today.years ago and still use today.

The most common one is labelled 2HD The most common one is labelled 2HD which means two-side, high-density.with which means two-side, high-density.with the two-side label data can be saved on the two-side label data can be saved on both sides.both sides.

This disk has the capacity of 1.44 This disk has the capacity of 1.44 megabytes which is about 350 typewritten megabytes which is about 350 typewritten pages.pages.

The floppy has a thin exterior jacket made The floppy has a thin exterior jacket made of plastic to protect the flexible disk.of plastic to protect the flexible disk.

There is a shutter on the disk that slides to There is a shutter on the disk that slides to the side to expose the recording surface. the side to expose the recording surface. There is also a label to name the disk.There is also a label to name the disk.

There is a write-protection notch that slides There is a write-protection notch that slides open and close. Files can be read in any open and close. Files can be read in any direction.direction.

Files are stored and organized on the floppy Files are stored and organized on the floppy according to tracks and sectors. Tracks are according to tracks and sectors. Tracks are rings of concentric circles with out visible rings of concentric circles with out visible grooves. grooves.

Sectors tracks that are divided into invisible Sectors tracks that are divided into invisible wedge-shaped sections. Each can store 512 wedge-shaped sections. Each can store 512 bytes.bytes.

High Capacity Floppy High Capacity Floppy DisksDisks

Known as the floppy-disk cartridge. Also has 3Known as the floppy-disk cartridge. Also has 31/2 1/2 inch diameter. But inch diameter. But are able to store more information, are thinker and require are able to store more information, are thinker and require different kind of special drive:different kind of special drive:

Zip disks have 100 MB, 250 MB, or 750 MB capacity. Internal zip Zip disks have 100 MB, 250 MB, or 750 MB capacity. Internal zip drives are standard on many of today's system units.the external drives are standard on many of today's system units.the external one are usually connected to the system unit using a UBS port.one are usually connected to the system unit using a UBS port.

HIFD disks from Sony and holds a capacity of 200 MB or 720 MB. It HIFD disks from Sony and holds a capacity of 200 MB or 720 MB. It is able to read data on today's traditional disks as well as they is able to read data on today's traditional disks as well as they could on their own. could on their own.

Super Disks are made from Imation and have a capacity of 120 MB Super Disks are made from Imation and have a capacity of 120 MB or 240 MB.just like HIFD disk they are able to use traditional or 240 MB.just like HIFD disk they are able to use traditional disks.disks.

Hard-Disk CartridgesHard-Disk Cartridges Known as removable hard disks and are Known as removable hard disks and are

easy to remove as a cassette from a easy to remove as a cassette from a videocassette recorder.videocassette recorder.

The amount of storage on a computer The amount of storage on a computer system is limited only by the number of system is limited only by the number of cartridges.cartridges.

Use to complement a internal hard disk.Use to complement a internal hard disk.

Hard disks have capacities of 10 to 20 Hard disks have capacities of 10 to 20 GB.the most common use one is from GB.the most common use one is from Iomega called Peerless disk.Iomega called Peerless disk.

For note book computers they have the For note book computers they have the PC Card hard disk they credit card size PC Card hard disk they credit card size and holds up to 5 GB.and holds up to 5 GB.

Well known IBM’s Microdrive and Well known IBM’s Microdrive and Toshiba's MK5002.Toshiba's MK5002.

Internal Hard DiskInternal Hard Disk

Also known as fixed disk disk is located inside system Also known as fixed disk disk is located inside system unit. unit.

Is designated as the C drive. Is designated as the C drive.

Is use to store programs and large data files.Is use to store programs and large data files.

Two advantages over floppy: Capacity and access Two advantages over floppy: Capacity and access speed.speed.

It has a 100-gigabyte internal hard disk which can hold It has a 100-gigabyte internal hard disk which can hold as much information as 70,000 standard disks.as much information as 70,000 standard disks.

Performance Performance EnhancementsEnhancements

Disk caching improves hard-disk performance by anticipating data Disk caching improves hard-disk performance by anticipating data needs. It performs a function similar to Ram caching.needs. It performs a function similar to Ram caching.

Redundant arrays of inexpensive disks (RAID) improve Redundant arrays of inexpensive disks (RAID) improve performance by expanding external storage, improving access performance by expanding external storage, improving access speed, and providing reliable storage.speed, and providing reliable storage.

File compression and file decompression increase storage capacity File compression and file decompression increase storage capacity by reducing the amount of space required to store data and by reducing the amount of space required to store data and programs.programs.

File compression programs scan files for ways to reduce the File compression programs scan files for ways to reduce the amount of required storage.amount of required storage.

Compact DiscCompact Disc Compact DiscCompact Disc is also known as a CD. It is also known as a CD. It

is one of the most widely used optical is one of the most widely used optical formats. CD drives can hold 650 MB to formats. CD drives can hold 650 MB to 1 GB.1 GB.

Read only-CD-ROM ( COMPACT DISC-Read only-CD-ROM ( COMPACT DISC-READ ONLY MEMORY).READ ONLY MEMORY). This means it This means it can not be written on or erased by the can not be written on or erased by the user. user.

Write once-CD-R (CD Recordable).Write once-CD-R (CD Recordable). It It can only be written to once after that it can only be written to once after that it can be read many times. It can not be can be read many times. It can not be erased.erased.

Rewriteable-CD-RW (compact disc Rewriteable-CD-RW (compact disc rewritable).rewritable). Similar to CD-R, but disc Similar to CD-R, but disc surface is not permanent. Mostly used surface is not permanent. Mostly used to edit and create multimedia to edit and create multimedia presentations.presentations.

Picture CDs/Photo CDsPicture CDs/Photo CDs use a special use a special format developed by Eastman Kodak format developed by Eastman Kodak to store digital images.to store digital images.

Digital Versatile DiscDigital Versatile Disc DVD stands for digital versatile disc or digital video disc.

DVDs and CDs are very similar DVD disc can store 4.7 GB to 17 GB on a single DVD disc-17 times the capacity of CDs.

Read only-DVD stands for digital versatile disc-read only memory it provide over two hour of very high-quality video and sound comparable to what's found in motion pictures theatres.

Write once-DVD-R and DVD+ are two competing write once format. Both stand for DVD recordable.

DVD-R and DVD+R drives are typically used to create permanent archives for large amounts of data and to records videos.

Rewritable- three most widely used formats are DVD-RW,DVD+RW, and DVD-RAM.

DVD-RW and DVD+RW stands for DVD rewritable. DVD-RAM stands for DVD random-access memory.

DataPlayDataPlay Is an optical write once Is an optical write once

format similar to CD-R. format similar to CD-R.

Size of a quarter with the Size of a quarter with the capacity of 500 MB or capacity of 500 MB or enough to hold five hours of enough to hold five hours of CD-quality sound.CD-quality sound.

Uses includes storing and Uses includes storing and playing music files.playing music files.

The music industry The music industry supports these the most.supports these the most.

Solid- State StorageSolid- State Storage Solid-state storage devices have no moving Solid-state storage devices have no moving

parts. Data and information are stored and parts. Data and information are stored and retrieved electronically directly from these retrieved electronically directly from these devices much as they would from devices much as they would from conventional.conventional.

Flash memory cards are solid-state storage Flash memory cards are solid-state storage devices widely used in notebook computer.devices widely used in notebook computer.

Flash memory is also used in a variety of Flash memory is also used in a variety of specialized input devices to capture and specialized input devices to capture and transfer data to desktop computer.transfer data to desktop computer.

Key chain hard drives have recently been Key chain hard drives have recently been introduction. Key chain flash memory introduction. Key chain flash memory devices are compact and can be devices are compact and can be transported on a key ring or a necklace.transported on a key ring or a necklace.

Key chain hard drives conveniently connect Key chain hard drives conveniently connect direct to a computer’s UBS port to transfer direct to a computer’s UBS port to transfer files and have typical capacities of 1 GB.files and have typical capacities of 1 GB.

Internet Hard DrivesInternet Hard Drives User storage site on the internet. Also known as I-drive or online User storage site on the internet. Also known as I-drive or online

storage.storage.

The advantages over other secondary storages is the lower cost The advantages over other secondary storages is the lower cost and flexibility to access information from any location using the and flexibility to access information from any location using the internet.internet.

Access speed is a little slower because information has to travel all Access speed is a little slower because information has to travel all across the internet.across the internet.

Often used as a specialized secondary storage device.Often used as a specialized secondary storage device.

Sites focus on supplying services to businesses or to individuals.Sites focus on supplying services to businesses or to individuals.

Magnetic TapeMagnetic Tape Sequential access and direct access are Sequential access and direct access are

the two different approaches to the two different approaches to external storage.external storage.

Tapes provides slower sequential Tapes provides slower sequential access and disk provides fast direct access and disk provides fast direct access.access.

Like the floppy and hard disk magnetic Like the floppy and hard disk magnetic tape stores data and programs by tape stores data and programs by altering the electromagnetic charges on altering the electromagnetic charges on a recording surface.a recording surface.

Computers once used exclusively used Computers once used exclusively used magnetic tape reels.magnetic tape reels.

This type of tape is ½-inch wide and 1 This type of tape is ½-inch wide and 1 ½-mile long and provides a massive ½-mile long and provides a massive storage.storage.

Today computers use tape cartridges or Today computers use tape cartridges or magnetic tape streamers to back up magnetic tape streamers to back up data.data.

The EndThe End