Transcript Document 7293184

Computer Systems 1
Fundamentals of Computing
Performance, Data + Health & Safety
Performance, Data & Jargon
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Performance Terms
 Operational
 CPU
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Specific
Data Representation
 Analogue
Vs Digital
 ASCII
 Unicode
 Data
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Reduction
Jargon
 Deciphering
some computing terminology
Computer Systems 1 (2004 - 2005)
Performance Terms
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FLOPS
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FLoating Point Operations Per Second
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Another way to measure processor speed
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How many fractional calculations can processor carry out?
Processors often have a FPU (Floating Point Unit) designed to do
these calculations
 Improve number intensive tasks
 Such as graphics rendering
 Also called maths-coprocessor
MFLOPS = MegaFLOPS (MillionFLOPS /s)
GFLOPS = GigaFLOPS (BillionFLOPS /s)
Thought to be inaccurate
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Some operations can take longer than others
Computer Systems 1 (2004 - 2005)
Performance Terms
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‘Benchmark’
 The measuring stick against which something is measured
 Tests which have been devised to measure a specific type of
equipment or program
 Used to measure and compare performance of computer
software of hardware
‘Overclock(ing)’
 Processes happen in sync with clock cycle
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Theory: Quicker Clock = Quicker Computer
Forcing a CPU to run faster than it’s approved and tested speed
Used to force a little more power out of the processor
Risks attached
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Overheating of CPU
Processing errors
Computer Systems 1 (2004 - 2005)
CPU Types / Performance
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CISC
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Complex Instruction Set Computer
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RISC
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Reduced Instruction Set Computer
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Supports up to 200 instructions
Instructions for complex operations
Original Pentium processors & x86
Less instructions than CISC
Less Instructions = Faster (?)
Cheaper to produce
Puts bigger burden on software (?)
Motorola processors found in Apple computers
Pentium 2, 3 & 4 Use CRISC
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Combination of CISC & RISC
Computer Systems 1 (2004 - 2005)
CPU Performance
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‘Pipelining’
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Technique used in modern processors
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CPU fetches next instruction while processing current instruction
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Pipeline split into segments
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Each segment executes a specific function in sync with other segments
then data is moved along
 Sync is produce by clock cycle
Pipeline Segments
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A bit like a factory assembly line
Fetch
Decode
Execute
Can reduce bottleneck restrictions
Computer Systems 1 (2004 - 2005)
CPU Performance
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‘Pipelining’
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Example:
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Four instructions to carry out
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1, 2, 3 & 4
Pipeline Segments
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Fetch (F), Decode (D), Execute (E)
Clock Cycle
F(1)
F(2)
F(3)
F(4)
D(1)
D(2)
D(3)
D(4)
E(1)
E(2)
E(3)
Computer Systems 1 (2004 - 2005)
E(4)
CPU Performance
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‘Hyper-Threading’
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Hyper-Threading Technology (HT Technology) is
a groundbreaking technology that enables a
processor to execute two threads in parallel —
allowing you and your software to multi-task more
effectively than ever before. (Intel)
Computer Systems 1 (2004 - 2005)
CPU Performance
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‘Hyper-Threading’
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Based on the Simultaneous Multi-Threading (SMT) method
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Parallel execution of process threads
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Allows programs to run multiple threads in parallel on one
processor
 A Thread can be thought of as a single task that makes up
a process
 Involves creating two logical processors
 System becomes a pretend dual-processor machine
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A logical processor can be multi-tasking
 Provides multi-tasking through time-slicing
Is a theoretical parallel processing system
Fools the OS into thinking there are two processors
Computer Systems 1 (2004 - 2005)
Problem Prevention / Solving
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UPS
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Un-interruptible Power Supply
 Battery backup System
 Can also perform power conditioning and surge
protection
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‘Cleans’ power supply
POST
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Power On Self Test
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Checks performed by the BIOS when computer is powered up
Beep codes
Also have POST diagnostic cards
Computer Systems 1 (2004 - 2005)
Analogue
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A continuously varying signal
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Varying in terms of frequency, amplitude, or both
A signal that is constantly changing
Analogue can represent many values
Computer Systems 1 (2004 - 2005)
Digital
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A signal with discrete value changes
Signal levels are either on or off
Often thought of as either 1 or 0, especially in
computers, but digital can represent many
different values using discrete levels
Computer Systems 1 (2004 - 2005)
Basic Data Representation
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ASCII
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American Standard Code for Information
Interchange
 Represents English language characters
using numbers (0 to 127)
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7 bits for each character
E.g- 115 is a small ‘s’
 Extended ASCII (uses 8 bits = more
characters)
 http://www.asciitable.com/
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Computer Systems 1 (2004 - 2005)
Basic Data Representation
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Unicode
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Another standard for representing language
characters
Uses 16 bits for each character
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> 65,000 unique characters
Useful for complex languages (Greek, Japanese, etc.)
special characters, symbols, etc.
May ultimately replace ASCII
www.unicode.org
Computer Systems 1 (2004 - 2005)
Data Reduction
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‘Compression’
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Using an algorithm to reduce the size of a computer
file or program
 Loss-less compression
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Information is compacted without destroying or removing
any data from the file
E.g- zipping a file
Lossy compression
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Information is compacted but information deemed to be
insignificant or redundant is thrown away
E.g- MP3
Computer Systems 1 (2004 - 2005)
Jargon Busting
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AI
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Artificial Intelligence
Attempting to make the computer behave like a human or think
for itself
Used in games to simulate human and random behaviour
Expert systems or knowledge bases allow decisions or
recommendations to be given based on input
Meta
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Information about information
Thing of Meta as meaning “about”
Meta-data = data about data
Meta-language = a language about a language
Computer Systems 1 (2004 - 2005)
Jargon Busting
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HCI
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Human Computer Interaction
How the user and computer communicate and interact with each
other
Make interaction faster, easier and better
Many different forms of interaction:
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Haptic: movement, gestures, physical interaction
Auditory: using sounds to interact
Pervasive Computing
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“Ubiquitous Computing”
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Integration of computing technology to everyday life
Introducing technology into everyday ‘ordinary’ objects
Allowing everything to be networked and live
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Computer Systems 1 (2004 - 2005)
What you know now:
 Performance
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Hyper-threading
Pipelining
Problem solving
 Data
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Representation
Analogue Vs Digital
ASCII
Unicode
Compression
 Jargon
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AI
HCI
other jargon...
Computer Systems 1 (2004 - 2005)
Health & Safety
Computer Systems 1 (2004 - 2005)
Health & Safety
Working with computers
 Effects on life
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 Health
& Safety
 Social aspects
 Legal requirements / implications
 Equipment specific aspects
 Environmental issues
 Ergonomics
Computer Systems 1 (2004 - 2005)
Working with computers
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Risks and effects associated with computer use
These are not only health related but also have
social and economical implications
Computers and technology encroach on many
aspects of everyday life
 Desktop
computers
 Laptop computers
 PDA’s
 Mobile phones
Computer Systems 1 (2004 - 2005)
Working with computers
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“All businesses must ensure their workplace
- whether this is a factory, office or shop meets minimum health and safety
standards.”
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IT Related employer responsibilities:
 carrying
out a risk assessment
 ensuring employees use IT equipment safely
 reporting accidents or dangerous incidents in the
workplace to the relevant authorities
UK Law (www.businesslink.gov.uk)
Computer Systems 1 (2004 - 2005)
General Health & Safety
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Risk Assessment
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All business must carry out an assessment
Issues
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What are the potential hazards?
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What hazard prevention measures are in place?
Five Step Risk Assessment
1.
2.
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4.
5.
Look for the hazards
Decide who might be harmed and how
Evaluate risks and decide whether existing precautions are
adequate or whether more needs to be done
Record your findings
Review your risk assessment from time to time and revise it
Computer Systems 1 (2004 - 2005)
General Health & Safety
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Equipment Regulations
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Equipment must be suitable and safe to use under the
Provision and Use of Work Equipment Regulations 1998
(PUWER).
All equipment must be:
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suitable for its intended use
maintained in a safe condition
accompanied by suitable safety measures such as protective
devices, markings and warnings
Only people who have received adequate information,
instruction and training use the equipment.
Computer Systems 1 (2004 - 2005)
Specific IT Regulations
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Health and Safety (Display Screen
Equipment) Regulations 1992
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Measures:
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Ensure workstations and workplace layout
meet a range of minimum requirements in
areas such as clarity of image, adjustable
chairs and suitable lighting
 Ensure staff receive a Display Screen
Equipment risk assessment and arising
problems are resolved
Computer Systems 1 (2004 - 2005)
Specific IT Regulations
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Health and Safety (Display Screen Equipment)
Regulations 1992
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Measures continued:
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Give staff regular breaks away from display screens
Pay for employees' eye tests on request
Provide training so staff can use their VDU and
workstation safely
VDU User Guide
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http://www.hse.gov.uk/pubns/indg36.pdf
Computer Systems 1 (2004 - 2005)
Health and Safety
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Predominantly because of keyboard and
mouse use
 RSI
(Repetitive Strain Injury)
Primarily affects the hand and arms (pain!!!)
 Can cause permanent damage
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 CTS
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Mainly affects the wrists of computer users
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(Carpal Tunnel Syndrome)
Especially in the mouse hand
Swelling of tendons, causes pressure on the
nerves
Computer Systems 1 (2004 - 2005)
Health and Safety
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VDU use
 VDU
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= Visual Display Unit
The monitor or screen to you and I
 Eye
strain
 Poor positioning of monitor
 Issues with electrostatic fields
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Skin and eye irritation
 Magnetic
& light radiation
 Issues with electromagnetic fields
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Reduction of immune system effectiveness
Computer Systems 1 (2004 - 2005)
Solutions - Overview
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Working environment
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OHSA (US)
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Occupational
Health and
Safety
Administration
www.osha.gov
UK Health and
Safety Executive
 www.hse.gov.uk
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Computer Systems 1 (2004 - 2005)
Solutions - Overview
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Ergonomics
 Correct posture
 Positioning of components
 Copy holders
 Better work environment
 Adjustable chair, desk, etc.
Wrist supports
Monitor filters
Regular breaks
Computer Systems 1 (2004 - 2005)
VDU Legal Requirements
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Computer screens should:
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tilt and swivel to suit the needs of the user
be adjusted to the correct height for the user
show clear characters with adequate spacing
show a stable image with no flickering
have easily adjustable brightness and contrast controls
be free of reflected glare
have a screen size suitable for its intended use
You should also ensure that users know:
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how to adjust brightness and contrast controls to suit
keep the screen surface clean
how to adjust software settings to make text large enough to read
easily
take frequent breaks
Computer Systems 1 (2004 - 2005)
Keyboard Legal Requirements
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Keyboards should:
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be tilt adjustable and separate from the screen to
allow the user to work comfortably
have enough space in front of them to allow the user
to rest their hands and arms when not keying
be legible and have a matt surface to minimise glare
You should also ensure that users:
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adjust the keyboard to get a comfortable position
keep their wrists straight when keying
use the keys lightly and not overstretch their fingers
take frequent breaks
Computer Systems 1 (2004 - 2005)
Pointing Device Legal Requirements
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If an employee uses a mouse, trackball or other
pointing device for long periods, they may develop
problems in their hands, wrists or upper body
Minimise risk by:
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Train user to use the mouse with relaxed arm and a straight wrist
informing the user that their fingers should rest lightly on the
buttons and not press too hard
limiting the length of intensive mouse sessions
ensuring users take frequent short breaks
ensuring the device is suitable for the task
training the user in keyboard shortcuts
training the user to adjust the software settings - these control the
reaction time between the mouse and the cursor on the screen
Computer Systems 1 (2004 - 2005)
Laptop Advice
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Some design features on laptops and
portable computers can make them
uncomfortable to use for long periods
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Employees shouldn't therefore use laptops
where full-sized equipment is available
Laptops should:
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be as light as possible - 3kg or under
be fitted with as large and clear a screen as
possible
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preferably detachable or height-adjustable
come with a lightweight carrying case with
handle and shoulder straps
Computer Systems 1 (2004 - 2005)
Laptop Advice
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Laptops should:
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have a tilt-adjustable keyboard
be able to be used with a docking station
have friction pads underneath to prevent
sliding across work surfaces
 have enough memory and speed for the
software used
 be fitted with as long a battery life as possible
and have extra transformer/cable sets
provided so that the user has a set in each
main location where the equipment is used
Computer Systems 1 (2004 - 2005)
Laptop Advice
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Laptops users should be aware of:
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comfortable postures for using a laptop
using the keyboard at the right height
adjusting the screen to reduce reflection and
glare
 the need for regular rest breaks
 how to report any problems that develop
 how to reduce the manual handling risk,
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eg by reducing the amount of extra equipment
and paperwork to be carried
how to reduce the risk from theft or mugging
Computer Systems 1 (2004 - 2005)
The Workstation
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Desks:
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big enough to allow the user to arrange the screen,
keyboard, documents, etc in a flexible way
 have a matt surface
 big enough to let the user work comfortably & change
position
 be stable and positioned so that it's comfortable and
easy to use where an employee uses a document
holder
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Chair:
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be stable and allow the user to work comfortably
be adjustable in height
have a seat back adjustable in height and tilt
Computer Systems 1 (2004 - 2005)
Social Implications of Computers
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Computers are everywhere!
 IT training becoming a necessity
 Everyone prone to health and safety issues with
technology
 Stress / ‘Computer rage’
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Software manufacturers fault?
Information easily available and easy to share
Less need for social interaction
Why can’t the computer do it?
Laziness?
Un-sociable society?
Computer Systems 1 (2004 - 2005)
Health & Safety
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What you know now:
 Aspects
of safety
 General working requirements
 IT Specifics
Monitors
 Working with computers
 Health & Safety Issues
 VDU usage
 Workstation
 Equipment safety
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Computer Systems 1 (2004 - 2005)