Input, Output and Backing Storage
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Transcript Input, Output and Backing Storage
Computer
Systems
Nat 4/5 Computing Science
Input, Output and Backing
Storage
Lesson 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, webcam
Describe 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
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Input Devices
An
input device is a device which creates
some new information to put INTO the
system
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Output Devices
An
output device is a device which gets
information FROM the system
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Input/output Devices
You
have to be able to compare these
devices in terms of appropriate
characteristics such as:
Resolution
Capacity
Speed of data transfer
Cost
Backing Storage
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Storage Terms
Term
Abbreviation
Description
binary digit, 0 or 1
Byte
a group of 8 bits – Single Letter
Kilobyte
Kb
1024 bytes
Megabyte
Mb
1024 Kilobytes
Gigabyte
Gb
1024 Megabytes
Terabyte
Tb
1024 Gigabytes
BIGGER ->
Bit
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Types Of Access
Sequential Access
To go from file A to file
Z in a sequentialaccess system, you
must pass through all
files in order.
Sequential access is
sometimes called serial
access
Direct/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
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Backing 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
Optical
These store data by means of lasers ‘burning’ a disk
Floppy Disks/Hard Disk Drives
Magnetic Tapes
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 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
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
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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.
Type Of Access
Direct/Random
Capacity
Up to 3TB
Portability
Not portable
Transfer Rate
Up to 600Mbps
Price
Approx £40 - £220
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Magnetic 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
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
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Optical Storage – CD/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
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
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USB 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
Type Of Access
Direct/Random
Capacity
Up to 128GB
Portability
Very portable, only requires USB port
Transfer Rate
10-30MBps
Price
£10-£100+
Summary
There
Optical
Magnetic
Solid State
There
are three main types of backing storage
are two main types of access
Sequential
Direct/Random
Input
Devices put information INTO the
computer
Output Devices get information FROM the
computer