CP1610:Introduction to Computer Components

Archival Storage Devices

What is Archival Storage?

Similar to secondary storage. Typically more durable. Used for long-term or permanent storage:

Data backups from hard disks;Permanent storage of data that will not be

changed (ex: music or movies);

Common Archival Storage Media

Optical Storage Flash Memory Magnetic Storage

Optical Storage

Use light (lasers) to read and write data. Not subject to data loss or corruption. Compact Discs (CD’s) Digital Video Disks (DVD’s)

How Optical Storage Works

Light is used to burn a series of ‘pits’ (dark spots) on a disk.

Dark spots and light spots are read as 0’s and 1’s (binary).

Re-writable discs use ‘Phase’ technology:Special dyes are used that react to the laser;The ‘Phase’ of the dyes can be changed to

change the data.

Data Storage on Optical Media

CD-ROM drives Use CDFS (Compact Disc File System) or UDF (Universal Disk

Format);

Hold about 780 MB of data.

DVD drives Use only UDF;

Uses the MPEG-2 encoding standard;

Standard hold about 4.5 GB of data.

Dual-layered DVD’s can hold up to 8.5 GB of data.

Optical discs have tracks and sectors, just like magnetic disks.

Tracks and sectors are arranged in a spiral, instead of concentric circles.

Floppy Disk

Flash Memory

Also called solid-state storage. No moving parts (Data on the media is altered

using electrical signals). Relatively high memory capacity. Commonly used for:

USB drives; MP3 players; Digital camera memory; Mobile phone and PDA memory;

Multimedia Compression Standards

MPEG-1 standard Image compression for business/home applications

MPEG-2 standard Video film compression on DVD-ROM

MPEG-3 standard Audio compression

MPEG-4 standard Video transmissions over the Internet

Magnetic Storage

Like a cross between a floppy or hard disk, and an audio cassette.

Stores data by aligning magnetic particles on a ‘tape.’

Magnetic particles are read as 0’s or 1’s (binary).

Advantages of Magnetic Storage Advantages

Inexpensive and convenient

Large capacity

Several types and formats

Disadvantage

Sequential access

Other Archival Storage Media ZIP Disks (By Iomega)

and SuperDisks (by Imation). Similar to 3.5 inch floppy

disks, but bigger, with more capacity.

Never became popular because of CD’s and DVD’s