Computer Systems 1 Fundamentals of Computing Performance, Data + Health & Safety

Computer Systems 1Fundamentals of Computing

Performance, Data + Health & Safety

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


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


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


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


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


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)


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)


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


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


Analogue A continuously varying signal

Varying in terms of frequency, amplitude, or both A signal that is constantly changing Analogue can represent many values


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


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/


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


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


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


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


What you know now:Performance

Hyper-threading Pipelining Problem solving

Data Representation Analogue Vs Digital ASCII Unicode Compression

Jargon AI HCI other jargon...


Health & Safety


Health & Safety Working with computers Effects on life

Health & SafetySocial aspectsLegal requirements / implicationsEquipment specific aspectsEnvironmental issuesErgonomics


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


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)


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


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.


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


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


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


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


Solutions - Overview Working environment

OHSA (US) Occupational

Health and

Safety

Administration

www.osha.gov

UK Health and

Safety Executive www.hse.gov.uk


Solutions - Overview Ergonomics

Correct posture Positioning of components Copy holders Better work environment Adjustable chair, desk, etc.

Wrist supports Monitor filters Regular breaks


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


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


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


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


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


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


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


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?


Health & Safety What you know now:

Aspects of safetyGeneral working requirements IT Specifics

Monitors Working with computers Health & Safety Issues VDU usage Workstation Equipment safety

Documents

Computer Systems 1 Fundamentals of Computing Performance, Data + Health & Safety