IGCSE - ICT - Chapter 3

Storage device

A peripheral device that are used to hold data even when the computer is turned off.

Storage medium

is the part that holds the data

backing storage

some device outside of the computer to store data

Processor

can only use data and instructions in the memory

Magnetic storage media

store data as magnetized particles on a surface (hard drive)

Optical storage media

store data on their surface by little pits burnt by a laser into the surface

Solid-state storage

Also referred to as removal media, is a non-volatile, removable medium that uses intergrated circuits.

Fixed hard disk

They are the main method used for data storage. It has read/write heads allowing data to be written to or read from the disk surface.

Read/write heads

can write and read the data on the disk

Use of fixed hard disk

1. large storage capacity

2. quick access

3. no limit to the numbers of times they can delete and reuse the medium

Types of data it can store

1. O.S

2. User's applications

3. user's data

Direct access to data

the read/write head will brows in the index and lead straight to the data

Portable hard disks

useful for making backup of all the data in a system

Magnetic tapes

stored in a long line on the tape rather than being scattered over the surface of a disk

advantage--- cheaper

harder to be corrupted

Serial storage

data is stored one piece after another

Sequential storage

data stored in certain order

advantage--- make sure nothing miss out

CD

compact disk

storage limit about 1 GB

commonly used to store music files

DVD

digital versatile disk

use laser to read and write data

more squeezed therefore more data can be stored

R

recordable

RW

rewritable

Are CD-ROMS, DVD-ROMS changeable or unchangeable

unchangeable

CD-RS,DVDRS

make copy of files, store data. ( can only be changed once)

CD-RWs, DVD-RWs

ideal for moving files from one computer to another (can be edited repeatedly)

DVD-RAM

This is a recent addition to the optical media group. They can write and read at the same time.

HD-DVD

The high-definition optical disc formatting standard, promoted by Toshiba, that was defeated by the Blu-ray Disc standard as the widely accepted high-definition standard.

blu-ray

A disk that enables the recording, rewriting and play back of high-definition video and the storing of large amounts of data. It has more than 5 times the storage capacity of traditional DVDs and can hold up to 25GB on a single layer disk and 50 GB on a dual layer disk.

Memory disk

small

ideal for storing data and software that needs to be transported from one computer to another

Flash Memory cards

Small portable cards to which data can be written and rewritten.

Disavantage

price

life span

Very large storage capacity

Fixed hard disk

Portable hard disks

Magnetic tapes

Which storage media has a large storage capacity

Memory disks

Flash memory cards

Blu-ray/HD-DVD

DVD-ROM

DVD-R

DVD-RW

DVD-RAM

Limited storage capacity

CD

Very fast access to data

Flash memory cards

Memeory sticks and pen dirves

Fast access to data

Fixed hard disks

Portable hard disks

CD,DVD,Blu-ray

Slow access to data

Magnetic tape (speed)

Very portabel

Flash memory cards

Memory sticks

CD,DVD

Less portable because of size

Portable hard disks (portable, size?)

Not portable

Fixed hard disks (portable?)

archive

providing statistical information