Computer System Reliability
Necessary to be reliable and robust because society is dependent
Reliability improved by getting higher quality components and testing system in development
Robustness improved by using verification and validation techniques to prevent abnormal input
Robustness improved by testing erroneous inputs and preventing them in future
Important to be both reliable and robust because:
Non reliable systens could fail or crash --> medical situation or business have serious consequencies
Non robust systems can 'hang' --> prevent customer completing transaction
Reliability - ability of computer system to complete functions without failure
Robustbess - ability of computer system to continue operation normally despite abnormal inputs
Compatibility - ability of 2 different type computers to run same software
Interoperability - ability of different systems to exchange data using common standards
Standards - 1. Industry, 2. De facto, 3. Open, 4. Proprietary
1. Where hard/software endorsed by an organisation for standards. Advantage is USB cables can be gotten from different manufacturers because they have a standard configuration --> user choice
2. Exist where they have been accepted by majority of IT industry. eg QWERTY keyboard
3. (open source). User choose how to amend source for their needs, eg operating system Linux
4. (closed source). owned and defined by market leader. eg Apple control hardware and operating system for their computer devices.
Ethical and Environmental Considerations
Ethics - set of principles to promote what is morally 'good' for individuals and society
Ethical is set of principles to promote what is 'good'. different for different people. Software Engineering code of Ethics and Professional Practice is widely use
Environmental - consider recycling of devices, energy usage, sustainability
3 choices what to do with old device - Computer users should dispose of devices safely and delete data on device, Recycle devices, donate to less developed countries
Computers use lots energy cooling. energy supplies costly so make energy use efficient. Reduce heat made in system. Reuse waste heat to heat other parts of building to reduce energy usage.
Could use automatic energy-reduction devices like: auto-lights, auto-heating, low-energy devices
Sustainability - method of resource usage that aims to meet current needs and those for future
Increase use of sustainable resources by - Paper-free(online), electronic communication(not post), videoconferencing or teleowrking(no fuel).
Consider: 1. Data Protection Act, 2. Copyright Law, 3. Computer Misuse Act
1. ensure data held about clients was secure, up to date, and not kept longer than needed
Use software to help protect client data: Passwords - needs to be strong(numbers, symbols, upper&lowercase), Encryption - unreadable to people who do not have key to decode it, Selective drop-down menus - /sometimes used/ adds letters for a password istead of just typing.
2. protect property of material originally produced
Useful protecting: Software piracy - illegal copying of sotware, theft - competition purchasing software and reselling it cheaper (have no cost of development)
3. Prevent attacks on IT system eg Hacking - practice of breaking into secure computer systems, Viruses - programs desgined to casue damage to computer, Firewall - prevent unauthorised requests from hackers, Spyware - programs run in a computer system to gather info.
To counteract hacking, use firewall. Anti-virus software minimise risk of virus. Anti-spyware program detects and prevents spyware