Fundamentals of Computer Systems

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.

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