Transcript Hardware and Software

National 4 and National 5
Computer Science
Hardware Requirements (ISDD)
Technical Implementation:
Hardware Devices
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• input and output
devices
• processor clock speed
(Hz)
• memory (RAM, ROM)
• appropriate type of hardware
required for a specific
information system including:
• input and output devices
• processor type and speed
(Hz)
• memory capacity (RAM)
Computer Architecture
•Computer architecture - structure of a
computer system (5 block diagram)
MEMORY
INPUT
DEVICES
PROCESSOR
STORAGE
DEVICES
OUTPUT
DEVICES
Input Devices
•An input device is hardware which lets you
put information INTO the computer e.g.
• keyboard, mouse, trackpad
• microphone, sound card
• graphics tablet, touch sensitive screen
• joystick/controller
• digital still/video camera
• scanner
• webcam
• data glove
Output Devices
•An output device is hardware which allows
data to be displayed or passed out of a
computer system e.g.
•monitor
•printer – laser, inkjet, 3-D
•plotter
•loudspeakers and headphones
•sound card
•graphics card
•projector
Comparing Output Devices - Monitors
•LCD – Liquid Crystal Display (cheapest)
•LED – Light Emitting Diode – thicker than LCD
•OLED – organic LED – screens can be flexible
(most expensive)
Quality of display depends on resolution:
number of horizontal pixels X number of vertical rows
Inkjet Printer
- high quality text and graphics
- particularly good for printing photographs
- squirts ink onto the paper through small holes
in the print head
Laser Printer
- laser beam projects the image to be printed
onto a drum
- powder called toner sticks to image on the
drum
- toner transferred from the drum to the paper
Printer Speed
Pages Per Minute (PPM) – how many pages the
printer can produce in one minute
Colour printers have two ppm numbers
- one for monochrome (black and white) pages
- one for colour pages
Laser faster than Inkjet
3-D Printer
• 3-D printers produce three dimensional
objects.
• A CAD program is used to design the object.
Plotter
• like a printer but can print out onto very
large paper sizes
• most often used in Computer Aided Design
(CAD)
Sound card
(input and output device)
• improves the quality of sound output
• changes sound signal from digital to
analogue
• outputs signal to loudspeakers or
headphones
Graphics card
• improves the quality of the display signal
• contains it’s own RAM and processor so
reduces main processors workload
• especially good for hi-resolution games
• sends output to monitor or projector
Memory
•Used to store programs and data before and
after processing.
•Two kinds of memory chip – RAM and ROM
•Each used for a different purpose
RAM – Random Access Memory
•Holds running programs loaded from backing
storage (e.g. hard disk)
•Holds data temporarily – only while the computer
is ON – lost when computer is switched OFF
•Data in RAM can be altered by being written to
RAM – Random Access Memory
•May be written to / read from in any order by the
processor – a direct access medium
•Memory is divided into storage locations,
each location has a unique address
•More RAM improves computer performance:
• more / larger programs and files in RAM at once
• 100x faster to process files in RAM than hard disk
ROM – Read Only Memory
•Used to store data and program permanently
•Contents of ROM are NOT lost when computer is
turned OFF
•Contents of ROM written when ROM chip is
manufactured
ROM – Read Only Memory
•Data held in ROM may be read from in any order
by the processor – a direct access medium
•ROM contains part of the operating system (OS)
called the bootstrap loader, to help the computer
start when turned on. Bootstrap loader is used to
load the rest of the OS from disk.
Processor
•Processors carry out instructions. The
instructions come from a program (software).
•The part of the computer where sorting,
searching, calculating and decision making
happens.
Clock Speed
•Processors carry out instructions very quickly –
several billion instructions a second
•Clock speed is used to tell us how fast the
processor is capable of working
•Measured in GHz. 1 GHz is approx. 1,000 million
pulses a second.
Processor Cores
Clock Speed 1.6GHz
8 Cores
•To improve system performance
manufacturers now put > 1 processor or
‘core’ on a single chip.
•Dual core = 2 processors on one chip
•Quad core = 4 processors on one chip
Instruction Set
•Different processors support different instruction
sets
•Reduced Instruction Set Computers (RISC) have
simpler (not fewer) instructions than Complex
Instruction Set Computers (CISC)
•Simpler instructions take less time to execute, e.g.
in one clock cycle
What does the processor
do?
•Processor needs to do the following:
•fetch, decode and execute instructions
•perform arithmetic calculations and logical
operations
•control the system
•Uses a control unit, arithmetic and logical
unit and registers to do these tasks
Control Unit
•controls all the parts of the
processor
•makes sure program instructions carried out
in the correct order
•has a clock line that sends out a signal to
keep everything synchronized
Arithmetic and Logical Unit (ALU)
•carries out calculations (arithmetic)
•used to make decisions (logical operations)
e.g. is one number the same as, larger than or
less than another number
Registers
•temporary storage locations
within the processor
•store memory addresses, data or instructions
Example:
If the processor was performing the following:
is (5+4) > (6+1)
ALU and store the
1. Add the 5+4 using the _____
result of 9 in a register
_____
ALU and store the
2. Add the 6+1 using the _____
result of 7 in a register
_____
3. Fetch the 9 and 7 from _____
registers
ALU to calculate 9 > 7 and store
4. Use the _____
true in a register
_____
Buses
•The processor is connected to the rest of the
inside of a computer system (e.g. memory)
using buses
•A bus is a set of wires which each carry a 0 or
a1
Buses (cont)
•address bus – carries the memory location
(address) from the processor to memory and
other devices attached to the bus. It is
unidirectional (one way)
Buses (cont)
•data bus – carries the data to and from the
processor, memory and any other devices
attached to the database. It is bi-directional
(two-way).
Technical Implementation:
Storage
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Storage devices:
• built-in, external,
portable
• magnetic, optical
• capacity, speed
• rewritable, read-only
• interfaces
• local v. cloud
• built-in v. portable
• magnetic, optical, solid-state
including functionality and
capacity
• appropriate storage (type,
capacity and interface type)
for specific information
system
Interfaces
•An interface is hardware and software that
allow the processor to communicate with a
peripheral
•Peripheral – a device connected to the
outside of a computer.
•e.g.
•Input, output and storage
devices
Functions of an Interface
•Interfaces allow devices that work differently
to communicate with each other
•Differences may be:
•data is in different formats
•data transferred at different speeds
•devices operate at different voltages
Data format conversion
•computers use digital signals
•some devices use analogue signals
•sound, light and temperature are
all analogue signals
•interfaces need to convert between analogue
and digital or vice-versa
Digital to Analogue & vice-versa
•Can you think of any situations where a
computer system will need to convert
between
•digital and analogue?
•analogue and digital?
Data format conversion
e.g.
Playing an MP3:
Interface carries out digital
to analogue conversion
Playing a console game:
Interface carries out
analogue to digital
Data Storage
•Peripherals may work at different speeds
from the processor
•A keyboard or printer may transfer data more
slowly than the processor
•To solve this problem an interface can store
data temporarily so the processor and device
can communicate
Other Interface functions
•Voltage conversion - computer and
peripheral may operate at different voltages
•Status signals – communication between
computer and peripheral e.g. ‘ready to send
data’ or ‘I’ve run out of paper’
USB 2
•USB = Universal Serial Bus
•USB standardised the connection of devices –
many now use USB
•can only send OR receive data at any one time
•speed: 480 Megabits per second
Firewire
•IEEE 1394 / Firewire (Apple) / i.Link (Sony)
•designed for devices with large amounts of
data to transfer e.g. connecting digital
video camera
•speed: 800 Megabits per second
USB 3.0
•can send and receive data at the
same time
•speed: 10 x faster than USB2 (5 Gigabits per
second)
SATA
•SATA – connects storage drives to the
computer motherboard
•speed: can transfer up to 6 Gigabits per
second
Other Interfaces
•VGA / DVI / HDMI – graphics card to
monitor/projector
•Headphone jack
Types of Access
Sequential
Direct/Random
•to go from file A to Z
you must pass
through all other
files in order
•tapes are sequential
•to go from file A to Z
you jump directly to
Z
•disks are random
access
Backing Storage
• is not the same as memory
• used to store programs
• used to save permanent copies of your data /
files
• three main types: magnetic, optical & solid
state
Magnetic – Hard Disk Drives (HDD)
•magnetically charged metal disks
•read by a small head which moves over the
disks – direct/random access
•large storage capacity (how much it stores)
•speed (how fast disk is turning) measured in
rpm (revolutions per minute)
•high capacity and high speed are best
•internal or external (portable)
Magnetic – Tape
•just like music tapes (ask your parents!)
•to access a file must go sequentially through
every file by fast forwarding or rewinding
•cheap and easy to store
•often used for backups (as don’t need fast
access)
Optical
•Types:
•CD (Compact Disc)
•DVD (Digital Versatile Disc)
•Blu-Ray
•Need to know capacity – some discs have more
than one layer
•Form:
•ROM = Read Only – cannot be changed
•R = Writeable – can write data onto the disc
•RW = Rewriteable – can write data onto the
disc and change or delete it later
Optical (cont)
Optical disc storage capacities:
Type
Capacity
CD
700Mb
DVD
4.7Gb
Blu-Ray
25-50Gb
Optical (cont)
• spiral track is used to store the data
• laser is used to burn holes (pits) into the
surface of the disc
• lower power laser used to read the disc
Solid State
• Solid State Drive (SSD) - no moving parts –
data stored on chips
• also known as flash memory or flash ROM
(same as USB disks and memory cards)
• uses less power than optical or magnetic
drives
• fast access speeds
• many laptops use SSD
• internal or external (portable)
Cloud Computing
Cloud Computing is the use of computing
resources which are delivered as a service
over the internet.
One service of cloud computing is web/cloud
storage – storing your files on a server on the
internet.
Cloud Storage
Cloud Storage
Advantages of cloud storage:
• security – if you lose data locally, a backup
is available from the cloud
• storage capacity – virtually unlimited cloud
storage compared to local storage
• scaling – you can just buy more storage
space if you need it
• access – can access your files from
anywhere on multiple devices
Cloud Storage
Disadvantages of cloud storage:
• security – cloud providers will not accept
responsibility for lost data
• privacy – who can see your private files?
e.g. cloud company employees
• access time – need a fast internet
connection – consider upload v download
speed
• internet connection down = no file access
• cost – free for individuals but only up to a
certain capacity – companies usually need
to pay
Local Storage
Advantages
• privacy – only you can see your data
• availability – no problems accessing if
internet connection down
Disadvantages
• security – you need to backup your own files
• cost – need more space – you buy it
Technical Implementation:
Networking/Connectivity
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• stand-alone or
networked
• LAN/internet
• wired/wireless
• data speeds/ease of use of
wired/optical/wireless
• hardware required for
network connectivity: NIC,
router, hub, switch
• network type for specific
information system: hardware
+ transmission media
What is a network?
•A network is a linked set of computers which
can
•share programs and data
•send messages between them
•A computer not in a network is called a
stand-alone computer.
Types of network
• LAN – Local Area Network
• covers a small area such as a room or building
• school computers are connected to a LAN
• WAN – Wide Area Network
• covers a larger area such as a city or country or
more
• internet is a public WAN (a network of
networks)
Bandwidth
•Bandwidth or data transfer speed
•measure of the amount of data which may
be carried by a communications channel
(network or interface cable) at any one
time
•Measured in
Mbps – Megabits per second or
Gbps – Gigabits per second
Transmission Media
•Wired
•copper cables
•subject to electrical interference
•can be tapped (data read)
•corrodes over time
•low bandwidth
•cheap
Transmission Media
•Wired
•optical fibre
•not subject to electrical interference
•cannot be tapped
•does not corrode
•high bandwidth (1000x copper)
•longer range (100 x) than copper
•expensive
Transmission Media
•Wireless
•Bluetooth
•range 10m
•data transfer rate 1 to 3 Mbps
•good for temporary short-range links
between personal devices
Transmission Media
•Wireless
•Wifi
•range 30m inside
•range 200m outside (802.11n)
•data transfer rate 600 Mbps (802.11n)
•Microwave & Satellite
•used in telephone network
Why does your home network not
use Bluetooth?
• Range
not far enough
• Speed not fast enough
Networking Hardware
•Network Interface Card (NIC)
•connects a computer device to a network
•may be wired (Ethernet) or wireless (Wifi)
Networking Hardware
•Router
•connects two networks together e.g. house
or business to the internet
•home routers usually also contain a hub or
a switch to connect all your devices to
Networking Hardware
•Hub
•broadcasts data from server or router to
every device connected to the network
•inefficient – creates unnecessary network
traffic
Networking Hardware
•Switch (hubs smarter brother)
•an efficient version of a hub
•only sends data to the device it is meant
for
Connecting to the internet
•What networking hardware do you need to
connect to the internet?
wifi
NIC
or
ethernet
router
with hub /
switch in it
broadband
connection
+ Internet
Service
Provider
Network Structure
•Peer-to-Peer (P2P)
•all computers have the same status
•all information and programs stored locally
on that computer
•users must backup their own data
•login to different machines possible but
cannot access your files from another
computer
Network Structure
•Client/Server
•client workstations use resources from one
or more servers
•client – usually a desktop or laptop
•server – computer which handles requests
for data, emails, file transfers etc from
client computers – files from all users
backed up by system administrator
Types of Server
•File server
•central disk storage for users files and
programs
•larger storage capacity than a desktop
computer
•requires secure access (logging on)
•network and server need to be working to
access your files
Types of Server
•Print server
•controls a printer for use by client
computers
•provides a queuing facility so users get
their documents in turn
Benefits of networks over stand-alone
computers?
• share data and programs
• share peripherals
• email
• secure access (login) to protect files
Desktop
•mains (electricity) operated
•monitor, keyboard, pointing device (e.g.
mouse)
•hard disk drive or solid-state drive
•NIC (wired)
Laptop
•battery (rechargeable) operated (4-8 hours
usage)
•built-in LCD display, keyboard and pointing
device (track pad)
•hard disk drive or solid-state drive (more
common now)
•NIC (wired and wireless)
Tablet
•battery (rechargeable) operated
•touch sensitive screen – used for input and
output
•solid-state storage
•NIC (wireless)
Smartphone
•same features as a tablet but also allows
making and receiving phone calls
Mainframe
• processes large amounts of data at high
speed e.g. supermarket stock control,
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• multi-user or multi-access
• multi processor with large amounts of RAM
• dumb terminal (screen and keyboard) used
by users, all storage and
processing is done on
the mainframe
Supercomputer
•even more powerful than a mainframe
•used for intensive mathematical calculations
e.g.
•weather/climate forecasting
•digital animation for movies
Technical Implementation:
Software
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• Operating system
platform required
• OS purpose including: HCI,
running software, controlling
peripherals
• Web browser features
• Software required for a
specific Information System
Applications Software
Application – a program designed for a
particular task
Task might be a game, a word processor,
photograph editing etc.
Applications Software (cont)
e.g.
•Word Processor
MS Word
•Spreadsheet
MS Excel
•Database
MS Access
•Desktop Publishing
MS Publisher
•Photo Editing / Animation Serif Draw Plus
•Sound Editing
Audacity
•Movie Editing
Movie Maker
What software program do all
computers need?
Operating System (OS)
•software that controls the operation of the
computer
•no OS = useless computer, it can do nothing
without the OS
•two most popular:
Mac OS
Windows
Operating System Functions
HCI (Human Computer Interface)
•lets user give commands and see their effect
•graphical user interface (like Windows)
•command line interface (user types
commands)
Operating System Functions
Manages running software
•decides where in RAM running programs go
•makes sure the OS in RAM not overwritten by
user programs and data
Controlling peripherals
•manages receiving data from input devices
•manages sending data to output devices
Operating System Functions
Controls the security of the system
Lets the user know if errors have occurred
Manages file system
Operating System Example
How the Operating System helps a user who is going to
write a word document:
backing storage into the correct
1. Load MS Word from _____________
RAM
place in the computers _____.
2. Each time the user presses a key on the ________,
keyboard
the OS checks to see which key was pressed and
character on the screen.
displays the _________
3. When the document is finished the OS asks the user
RAM to
to name the file and saves it from _____
backing
storage
_____________.
4. If the user wants to print the document the OS
sends the data to the printer.
Your PC has 2.8 GHz Intel processor, 2GB RAM
and a half full 500GB hard disk. The operating
system is Windows 7.
Which of the following pieces of software will run
on your PC. Explain your answer.
System
Reqs
OS
Min.
Processor
Minimum
RAM
Storage
Grabbit
Windows
XP
2.7 GHz
Trappit
4 GB
Windows
Vista
2.8 GHz
(3.2 pref)
2 GB
25 GB
100 GB
Stoppit
Pausit
Windows 7 Windows 8
1.9 GHz
2.6 GHz
1 GB
3 GB
300 GB
40 GB