Computer Computer SystemsSystems

Nat 4/5 Computing Nat 4/5 Computing ScienceScienceInput, Output and Input, Output and Backing StorageBacking Storage

Lesson AimsLesson Aims By the end of this lesson: Pupils will be able to:

Describe the features, functions and uses of: keyboard, mouse, microphone, touchpad, digital

camera, scanner, webcamDescribe the features, functions and uses of

monitor, LCD panel, inkjet and laser printers, loudspeakers

Compare devices using appropriate characteristics including resolution, capacity, speed of data transfer, cost

Input DevicesInput Devices

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An input device is a device which creates some new information to put INTO the system

Output DevicesOutput Devices

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An output device is a device which gets information FROM the system

Input/output DevicesInput/output Devices

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You have to be able to compare these devices in terms of appropriate characteristics such as: Resolution Capacity Speed of data transfer Cost

Backing StorageBacking Storage

Storage TermsStorage Terms

Term Abbreviation Description

Bit binary digit, 0 or 1

BIGG

ER ->

Byte a group of 8 bits – Single Letter

Kilobyte Kb 1024 bytes

Megabyte Mb 1024 Kilobytes

Gigabyte Gb 1024 Megabytes

Terabyte Tb 1024 Gigabytes

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Sequential AccessSequential Access To go from file A to

file Z in a sequential-access system, you must pass through all files in order.

Sequential access is sometimes called serial access

Direct/Random AccessDirect/Random Access Refers to the ability to

access data at random. In a random-access system, you can jump directly to file Z.

Disks are random access media, whereas tapes are sequential access media

Types Of AccessTypes Of Access

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Backing StorageBacking Storage Backing storage is used to save permanent

copies of your files onto. There are 3 main types

Magnetic These use magnetic fields to store the data

Floppy Disks/Hard Disk Drives Magnetic Tapes

Optical These store data by means of lasers ‘burning’ a disk

CDROM/DVD/Blue Ray Solid State

This uses no moving parts at all, uses memory chips USB Drives SSD Hard Drives

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Floppy DisksFloppy Disks Floppy Discs are small pieces of plastic film

wrapped in a plastic case, they are fast becoming very scarce due to their slow transfer speed and limited capacity, have basically been replaced with USB Flash Drives

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Type Of Access Direct/Random

Capacity 1.44 Megabytes

Portability Very – Only requires another drive

Transfer Rate Very Slow – 500Kbps

Price Approx 25p per Disk

Hard Disk Drives (HDD’s)Hard Disk Drives (HDD’s) Hard Disk Drives are usually stored

inside the computer. They use disks of metal which are magnetically charged. These are read by a small head – like a

record player, which moves over the disks.

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Type Of Access Direct/Random

Capacity Up to 3TB

Portability Not portable

Transfer Rate Up to 600Mbps

Price Approx £40 - £220

Magnetic TapeMagnetic Tape Magnetic tapes are essentially the same

as music tapes. To access a file you have to sequentially go

through every file by fast forwarding or rewinding.

They are however relatively cheap and easy to store. Often used for backups

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Type Of Access Sequential

Capacity Up to 80GB

Portability Very portable, requires another drive

Transfer Rate Up to 7Mbps

Price Up to £20 per tape

Optical Storage – Optical Storage – CD/DVDCD/DVD

CD and DVD’s are optical media – a laser is used to burn holes (pits) into the surface of the disk. CD/DVD-R are recordable once CD/DVD-RW are rewritable more than once

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Type Of Access Direct/Random

Capacity CD: 700MB (80 minutes audio)DVD 4.7GB up to 50GB Blue Ray

Portability Very portable, requires another drive

Transfer Rate Approx 130Mbps

Price CDR: 20-30p DVDR: 30p-£1

USB Flash DrivesUSB Flash Drives USB (Universal Serial Bus) flash drives use

memory chips to store data, this means there are no moving parts at all – this is called solid state storage, this means they are very robust. These are often used in MP3 – Players – Ipod

Nano/Shuffle uses this. Some are even waterproof or branded with company

logos

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Type Of Access Direct/Random

Capacity Up to 128GB

Portability Very portable, only requires USB port

Transfer Rate 10-30MBps

Price £10-£100+

SummarySummary There are three main types of backing

storage Optical Magnetic Solid State

There are two main types of access Sequential Direct/Random

Input Devices put information INTO the computer

Output Devices get information FROM the computer