A computer is an electronic, programmable data processing machine. A system is a collection of parts that work together for a defined purpos. A computer system is a collection of hardware and software that works together to achieve a data processing task.
Systems recieve inputs which are processed into outputs from the results of processing. The system is separated from the outside world by a system boundary, these are often called interfaces.
Computer systems have meant;
- improved manufacturing quality - robot machinery
- cheaper manufacturing - reduce in wage costs
- faster access to information
- better decision making - facts are organised, available and people are better informed
Types of Computer system
- General purpose systems - computer systems used for a wide variety of purposes, e.g. laptops and tablets
- Dedicated systems - specially produced to perform single functions e.g. ticket vending machine
- Control systems - used to control machinery, used in manfacturing proces.
- Embedded system - dedicated function within a larger system, includes portable devices such as digital watches and cameras.
- Expert systems - designed to behave like humans would. They have a knowledge base, and inference engine (software that makes deductions using knowledge base) and an interface (allows user to access system). Can be used for diagnosing diseases and finding faults in machinery.
- Management information systems bring together all information from an organisation so managers can make decisions. They cover technology, data and people. Produce reports based on the organisations data e.g. school management information system used to deal with school administration
Reliability is expected when new computer systems are made. Mistakes in design lead to down time, expensive errors, data loss and compromised privacy
Reliability refers to data being accurate and consistant throughout its lifetime. This is known as data integrity, it also means that the stored data reflects real world reality. Database systems usually have rules which are used to prevent inconsistent changes being made to the underlying data. Data integrity can be compromised when human errors are made when data is entered. Errors can occur when data is transmitted from one computer to another moreover software bugs, viruses and malware can compromise data integrity. However risks can be reduced by, regularly backing up data, controlling access to data using secuity and using validation routines.
Reliability is improved through testing which is designed to uncover errors in the system. Testing can never be complete as software is very complex and testing it can be expensive and time consuming.
Standards refer to conventions and rules, they are normally defined by an organisation and the various standards that already exist are for programming languages, operating systems, data formats, communications protocols and electrical interfaces. Originally no standards existed and each manufacturer made up their own rules. Standards are important because they enable equipment from different manufacturers to work together. Moreover they make learning new systems easier as they will have similar characteristics.
De facto standards develop over time because of common use, they ensure files and systems can be accessed by anyone e.g. the QWERTY keyboard layout and microsoft word. De jure means by law, these are de facto standrds that have become so accepted that they will not change this includes PDF + Unicode.
Industry standards are set by recognised non commercial organisations for example ANSI , this company sets standards fro some programming languages. The IEEE sets standards for progamming languages.
Proprietary standards are owned by an orgnisation, these ensure that the companies products can be used together. These standards can be used to reduce competition from rival products and an example of this is APPLE. Proprietary standards are widley used however they are not approved by an independent standards body.
Open standards are publicaly available and produced collaboatively. This also means that they are not dominated by a specific group of people. Open standards are available either free of charge or at a very low price and are sufficiently detailed to allow interperability between developers. Open standards ensure that access to resources is not depedant on single applications or a particular hardware platform. An example of open standards is HTML or SQL.
Ethical and legal issues
An ethical act is morally right and a legal act is one that does not break any laws.
Data protection acts set up by governments protect the privacy of individuals when they have data on computer systems. The UK data protection act covers any data about a living and identifiable individual this is because it is becoming easier to copy, transmit and match data. Typical data protection laws contain rules that organisations must allow people to view data stored about them, correct information when requested, not use data in a way that will cause damage or distress and allow people to say that the data stored about them is not allowed to be used for marketing. The laws passed also state that the organisations should protect the data eficiently and only collect data for a specific purpose. Data is also not to be transmitted outside the EU, this as other areas may have different laws on collecting and transmitting data. Other laws that exist make it illegal to access or modify unauthorised computer material.
Cyber crime is criminal offence comitted with the aid of a computer. These are difficult to police due to the many international boundaries that the internet crosses.
The use of computers has been good for the environment as it reduces the need for travel and the transport of goods can be made by robots with a greater degree of accuracy. This means that more efficient products last longer and use enegy more efficiently. However, computers can cause waste and energy.
Computers contain many toxic materials such as lead, cadmium, beryllium and flame retardants. Computer waste is often shipped to developing countries where there are few safeguards. A lot of the waste goes into landfill where most of the chemicals leach into the soil. Old computers also contain plastics and when these are burned chemicals such as dioxins are produced. Computers and data centres use energy. Much of the enegy used is for air conditioning needed to keep the computers cool. To reduce energy used by computer systems;
- virtual servers - reduces number of physical severs used therefore less air conditioning needed
- solid state stoage - less enegy needed than rotating disk storage
- automatic standby - turns computers off when not in use
- laying out equipment so it can be cooled efficiently
- air condtioning at optimum level
- using modern screens - less energy intensive than CRT monitors