Post on 25-Dec-2015
Computer Systems 1 (2004 - 2005)
Performance, Data & Jargon Performance Terms
Operational CPU Specific
Data Representation Analogue Vs Digital ASCII Unicode Data Reduction
Jargon Deciphering some computing terminology
Computer Systems 1 (2004 - 2005)
Performance Terms FLOPS
FLoating Point Operations Per Second 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
Another way to measure processor speed MFLOPS = MegaFLOPS (MillionFLOPS /s) GFLOPS = GigaFLOPS (BillionFLOPS /s)
Thought to be inaccurate Some operations can take longer than others
Computer Systems 1 (2004 - 2005)
Performance Terms ‘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 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
Overheating of CPU Processing errors
Computer Systems 1 (2004 - 2005)
CPU Types / Performance CISC
Complex Instruction Set Computer Supports up to 200 instructions Instructions for complex operations Original Pentium processors & x86
RISC Reduced Instruction Set Computer
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 Combination of CISC & RISC
Computer Systems 1 (2004 - 2005)
CPU Performance
‘Pipelining’ Technique used in modern processors
CPU fetches next instruction while processing current instruction A bit like a factory assembly line
Pipeline split into segments Each segment executes a specific function in sync with other segments
then data is moved along Sync is produce by clock cycle
Pipeline Segments Fetch Decode Execute
Can reduce bottleneck restrictions
Computer Systems 1 (2004 - 2005)
CPU Performance ‘Pipelining’
Example: Four instructions to carry out
1, 2, 3 & 4
Pipeline Segments Fetch (F), Decode (D), Execute (E)
Clock Cycle
F(1) F(2)
D(1)
F(3)
D(2)
E(1)
F(4)
D(3)
E(2)
D(4)
E(3) E(4)
Computer Systems 1 (2004 - 2005)
CPU Performance ‘Hyper-Threading’
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 ‘Hyper-Threading’
Based on the Simultaneous Multi-Threading (SMT) method Parallel execution of process threads
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 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
UPS Un-interruptible Power Supply Battery backup System Can also perform power conditioning and surge protection
‘Cleans’ power supply
POST Power On Self Test
Checks performed by the BIOS when computer is powered up Beep codes Also have POST diagnostic cards
Computer Systems 1 (2004 - 2005)
Analogue A continuously varying signal
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 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 ASCII
American Standard Code for Information Interchange
Represents English language characters using numbers (0 to 127) 7 bits for each character
E.g- 115 is a small ‘s’ Extended ASCII (uses 8 bits = more characters) http://www.asciitable.com/
Computer Systems 1 (2004 - 2005)
Basic Data Representation
Unicode Another standard for representing language
characters Uses 16 bits for each character
> 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
‘Compression’ Using an algorithm to reduce the size of a computer file or
program Loss-less compression
Information is compacted without destroying or removing any data from the file
E.g- zipping a file Lossy compression
Information is compacted but information deemed to be insignificant or redundant is thrown away
E.g- MP3
Computer Systems 1 (2004 - 2005)
Jargon Busting AI
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 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 HCI
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:
Haptic: movement, gestures, physical interaction Auditory: using sounds to interact
Pervasive Computing “Ubiquitous Computing”
Integration of computing technology to everyday life Introducing technology into everyday ‘ordinary’ objects Allowing everything to be networked and live
Computer Systems 1 (2004 - 2005)
What you know now:Performance
Hyper-threading Pipelining Problem solving
Data Representation Analogue Vs Digital ASCII Unicode Compression
Jargon AI HCI other jargon...
Computer Systems 1 (2004 - 2005)
Health & Safety Working with computers Effects on life
Health & SafetySocial aspectsLegal requirements / implicationsEquipment specific aspectsEnvironmental issuesErgonomics
Computer Systems 1 (2004 - 2005)
Working with computers
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 “All businesses must ensure their workplace -
whether this is a factory, office or shop - meets minimum health and safety standards.”
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
Risk Assessment All business must carry out an assessment Issues
What are the potential hazards? What hazard prevention measures are in place?
Five Step Risk Assessment1. Look for the hazards2. Decide who might be harmed and how3. Evaluate risks and decide whether existing precautions are
adequate or whether more needs to be done4. Record your findings5. Review your risk assessment from time to time and revise it
Computer Systems 1 (2004 - 2005)
General Health & Safety
Equipment Regulations Equipment must be suitable and safe to use under the
Provision and Use of Work Equipment Regulations 1998 (PUWER).
All equipment must be: 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 Health and Safety (Display Screen
Equipment) Regulations 1992
Measures: 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 Health and Safety (Display Screen Equipment)
Regulations 1992
Measures continued: 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 http://www.hse.gov.uk/pubns/indg36.pdf
Computer Systems 1 (2004 - 2005)
Health and Safety
Predominantly because of keyboard and mouse useRSI (Repetitive Strain Injury)
Primarily affects the hand and arms (pain!!!) Can cause permanent damage
CTS (Carpal Tunnel Syndrome) Mainly affects the wrists of computer users
Especially in the mouse hand
Swelling of tendons, causes pressure on the nerves
Computer Systems 1 (2004 - 2005)
Health and Safety
VDU use VDU = Visual Display Unit
The monitor or screen to you and I Eye strain Poor positioning of monitor Issues with electrostatic fields
Skin and eye irritation Magnetic & light radiation Issues with electromagnetic fields
Reduction of immune system effectiveness
Computer Systems 1 (2004 - 2005)
Solutions - Overview Working environment
OHSA (US) Occupational
Health and
Safety
Administration
www.osha.gov
UK Health and
Safety Executive www.hse.gov.uk
Computer Systems 1 (2004 - 2005)
Solutions - Overview 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 Computer screens should:
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: 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 Keyboards should:
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: 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
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: 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 Some design features on laptops and
portable computers can make them uncomfortable to use for long periods
Employees shouldn't therefore use laptops where full-sized equipment is available
Laptops should: be as light as possible - 3kg or under be fitted with as large and clear a screen as
possible preferably detachable or height-adjustable
come with a lightweight carrying case with handle and shoulder straps
Computer Systems 1 (2004 - 2005)
Laptop Advice Laptops should:
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 Laptops users should be aware of:
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,
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 Desks:
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
Chair: 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 Computers are everywhere!
IT training becoming a necessity Everyone prone to health and safety issues with
technology Stress / ‘Computer rage’
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?