Chapter 1 (COMPUTER SYSTEMS: Integrated collection of part(hardware and…
COMPUTER SYSTEMS: Integrated collection of part(hardware and software) that work together for some defined purpose.
- A SYSTEM IS A COLLECTION OF PARTS WHICH WORK TOGETHER FOR A COMMON PURPOSE.
- An activity that involves input, processing and output is said to be a computer system.
- For a system to be useful it must produce something, an output . It needs to receive and process inputs in order to produce outputs. There may be many inputs and outputs.
- Systems often interact with other systems. systems may be made from many sub-systems. Interconnections between systems are called interfaces.
- Computer systems are an integral part of most people's lives.
- Computer systems are based on processing data and producing information . They are electronic which makes them fast and the important thing about them is that they are programmable. This means a computer can be made to do many things based on the instructions we give it.
SOME COMPUTER SYSTEMS ARE DEDICATED: -Dedicated :Something which is designed for a fixed purpose.
- e.g. an engine management system in a car is used to show faults and control its operation. It is not designed to do anything else.
SOME COMPUTER SYSTEMS ARE 'GENERAL PURPOSE' :
-General purpose computer systems:They can be used for different reasons according to what work needs to be done.
- PC's are general purpose and can run word processors, browse the internet and play music and movies.
SOFTWARE CAN BE DEDICATED TOO.
- In other words it is written for the particular device and the situation it controls.
- e.g. a computer chip controls a washing machine. It contains software that times each stage of the washing cycle, sets the water temperature and in some cases can react to sensors which detect how dirty the washing is.
- This software is sophisticated but it is not useful for controlling other devices, such as operating a camera.
DEDICATED COMPUTER SYSTEMS THAT ARE FOUND IN MOST ELECTRONIC DEVICES ARE CALLED EMBEDDED SYSTEMS:
- Embedded system: A computer system that forms part of an electronic device.
There may be a general purpose operating system such as Linux supporting dedicated software applications. This reduces the effort needed to write software for the device, because much of the functionality is 'borrowed' from the operating system. Examples of systems that make use of the Linux kernel include some GP navigation systems, media players and smartphones. The Android phone is based on the Linux kernel. -Kernel: The lowest level of an operating system that controls the hardware.
IMPORTANCE OF COMPUTER SYSTEMS IN THE MODERN WORLD:
- Embedded systems = Computers in the home are used to automatically control various systems and reduce workload. E.g. washing machine , central heating control, burglar alarm, dishwasher and security cameras.
- Home entertainment and communication = Most modern households use a range of computer-driven devices for entertainment and communication. Smartphones are widely used to surf the internet, send emails and make calls.
- Business = Most organisations use computer systems widely. E.g. videoconferencing, website creation, online sales, collaborative working.
- Medical systems = Doctors and hospitals use computer systems to treat patients and diagnose illnesses. E.g. administration, diagnostics with scanners and radio therapy.
AN ACTIVITY THAT INVOLVES INPUTS, PROCESSING AND OUTPUTS IS SAID TO BE A COMPUTER SYSTEM; COMPUTER SYSTEMS ARE BASED ON INPUTS, PROCESSING AND OUTPUTS.
E.g. Washing machine:
Input-Buttons, sensors including weight, temperature and water-level
Process- It uses data from these inputs to calculate water temperature
Output-It outputs information on a display and by using 'beeps'
- Input = This is where data is inputted into the computer system. It can be entered manually by using a keyboard to type in a part number into an online shopping form or by using a bar code to enter details of a sale at a supermarket.
- Process =This is where the data inputted is used to convert the input into a readable form; the bar code read in can be processed to obtain a description of the product, the size of the product and the price.
- Output = The information obtained by processing the data is resented to the user in a logical form; in the case of a supermarket, this could be to produce a display as the product is scanned in and all the products purchased could be printed out on a till receipt with suitable calculations when the shopping transaction is completed.
One way to ensure that systems are reliable is to adhere to certain standards .If a new system is developed according to defined standards, it is more likely to be successful and satisfy its users.
Standards also help to make sure that different computer systems can talk to each other.
These are standards owned by a company.For example, any software that runs under Windows must handle data in a certain way, communicate with the operating system in defined ways and work with a defined interface. Flash animations must conform to standards set up by Adobe company.
The advantage of this insistence on standards are that the system will:
- Look and feel familiar to users and this will speed up learning new systems
- Work in a predictable way, which will in turn improve reliability
- Be maintained by one company and although there will be different versions of the software, versions that contain minor updates are usually provided free of charge
- Sometimes known as closed source are owned and defined by a market leader a typical example is Apple computers that control the hardware and operating system for their computer devices, such as the iPad, iPhone, MacBook and iPod.
- Standards that are agreed across the computing industry. Many of these relate to hardware and allow easy interconnections between devices.
- One example is the Universal Serial Bus(USB), which has become the standard way to connect devices to most computer systems. The rage of devices that use USB connections is enormous.
- Industry standards are where the hardware of software is endorsed by a standards organisation such as ISO(International Standards Organisation).A typical benefit of industry standards is that the USB connecting cables can be obtained from a variety of manufacturers since they have a standard configuration, allowing the organisation to choose a cable at the right quality and price.
De facto standards:
- Some standards just develop through common usage until they become the accepted way of doing things.
- HTML started off as a de facto standard and as it gained popularity it became a de jure standard which means that you must adopt it if you want to communicate with anyone else.
- PDF started as a proprietary standard created by Adobe but the copyright was handed over to the International Organisation for Standardisation (ISO) in order to make the movement of digital files more open, so when free PDF readers became common, it was natural for them all to use the same format.The Microsoft Word doc standard has become the de facto standard for supplying word processed documents and all word processor programs need t be able to read ad write doc files.
- De facto standards exist when they have been adopted by a large sector of the ICT industry due to dominance in the market; for example the QWERTY keyboard layout has become the standard over a period of time.
- Open standards refer to standards that are publicly available, to an extent that software developed under them can be modified by users.
- They are becoming increasingly popular. The source code is publically available, so anyone with the time and expertise can make changes.
- Another feature of software produced under open standards is that it is often updated by a community of developers who make regular updates available to anyone usually for no or minimal cost.
- Software is often of very high quality because the community of developers act quickly to fix problems. However, there is no one to blame when things go wrong.
- Examples of open source software are the Android operating system, Linux, the Apache web server and the Python programming language.
- Open standards are sometimes linked to the term 'open source'; this is where the user has the option to modify the source code for their own purpose if they have the time and the necessary expertise. Typical examples of open standards are the operating system Linux and the programming software Python.
RELIABILITY = Is the ability of the computer system to perform the required function without failure. ROBUSTNESS = Is the ability of a computer system to continue to operate normally despite abnormal inputs or calculations.
- It is necessary for computer systems to be reliable and robust as society has become much more dependent on them.
- Reliability of computer systems can be improved by purchasing high-quality components and fully testing them during the development.
- Robustness can be improved by using validation and verification techniques to prevent abnormal inputs. Also when the computer system is commissioned, robustness can be improved by testing for erroneous inputs and then preventing them in the future using either hardware or software techniques.
In ICT standards are crucial in the areas of compatibility and interoperability between computer systems, which are defined as:
- When two machines from a different manufacture or specification run the same programs, they are considered to be software compatible.
- Interoperability enables different systems to work together and exchange data, and this is achieved by using common standards. This feature is mainly made use of in networking where two incompatible computers can interoperate if they both support the same networking protocol, such as the Internets TCP/IP.
- COMPATIBILITY = Is the ability of two different specification computers to run the same software.
- INTEROPERABILITY = Is the ability of different systems to exchange data using common standards.
- The Data Protection Act(1998) = Enacted in order to protect people's privacy . It contains a number of sensible safeguards such as demanding that those who keep personal data on a computer system should take care of it and protect it from unauthorised people. Similarly , people should be able to inspect any personal data held about them to satisfy themselves that it is accurate.
- The Data Protection Act was introduced to ensure that the data held on clients conformed to certain principles such as: being up to date, being held securely and not being kept longer than necessary.
- Keeping data secure is a key feature of this legislation and so when developing software application, it is necessary to add a range of software methods to help protect client data such as:
-Passwords entered into software applications should only be accepted if they are strong and so are more difficult to break; strong passwords are created by using a mixture of numbers, letters and symbols, using upper case and lower case, so that the final password does not look like a word.
-Encryption is used to make stored data more secure, by making it unreadable to people who do not have the key to decode it. This method is commonly used to protect data transmitted over the internet.
-Selective drop-down menus are sometimes used as a security method to add letters for a password, rather than just typing them; this prevents key-logging software from viewing systems and gaining access to important passwords
- Computer Misuse Act(1990) = Makes it illegal to gain unauthorised access to computer systems or to modify the data stored in them .
- The Computer Misuse Act was introduced with the express purpose of preventing attacks on ICT systems to commit crimes or to damage the system; this legislation made hacking and the introduction of a computer virus into criminal offences.
- Hacking is the process of breaking into a computer system and it is essential that preventative measures are taken. The main techniques are to utilise a firewall and to set u some intrusion detection.
- ICT systems are constantly communicating with the outside world, which involves connection to public networks and the associated difficulty of effectively policing access to the system.A firewall is a combination of hardware and software that is designed to check the integrity of incoming messages and requests for service from the system.
- Intrusion detection systems are designed to monitor the network or computer system for malicious activities. Once an incident is detected, a report is produced which is sent to the network management for further action to prevent any risk to the system.
-A computer virus is a program designed to cause damage to a computer system.The use of a virus scanner or anti-virus software helps to minimise the risk from viruses; this software searches the computer system for viruses and deletes them once detected.
-Spyware can be loaded into a computer system as a software virus. It is important to run an anti-spyware program which will prevent and detect spyware from being installed and to remove any spyware that has previously been installed.
Copyright Design and Patents Act(1998) = The Copyright Design and Patents Act aimed to protect the intellectual property of individuals and organisations that create and produce materials based on their own individual ideas.
-Protecting your copyright is especially worthwhile when you or your organisation have invented a new hardware or software concept.
- Copyright legislation is useful in protecting the following aspects of computer technology:
-Software piracy is the illegal copying of software for either personal or business use.
-Theft of hardware and software ideas and innovations . In an industry that moves so fast there is seldom time to patent your invention before you release it on the open market. Many organisations purchase their rivals products with the express purpose of copying their ideas, which saves them considerable expense on research and development.
- There are many websites that can help the create to protect or patent their work.The main implication for ICT organisations is that they make the public aware of their intellectual property rights; this can be achieved by ensuring that they include documentation with their products, stating that their designs are copyrighted, can't be modified or coped or to use 'reverse engineering' techniques to product replicas.
*The computer system developer needs to take account of the following environmental considerations:Recycling/Disposal of digital devices:
Climate Change and Energy Usage:
- Recycling can have many benefits in protecting the environment as it reduces that amount of landfill sites that are needed, which is useful since we're running out of landfill space.
- It is important that computer users dispose off their old digital devices safely by using the local authority waste disposal sites. In most cases, the user should delete any data from either their computer hard disks or from the SIM card on their mobile phone.
- Old digital devices can also be recycled to less developed countries to extend their useful working life.
- Old computer equipment is referred to as e-waste. Computers contain many toxic components . In the USA, old computers are referred to as hazardous waste. Much electronic waste is sent to landfill sites, where toxic materials can escape into the wider environment. Much waste is exported to countries with low standards or environmental protection . Sometimes children pick over the waste in order to extract metals that can be recycled and sold. This saves resources on a global scale but exposes children to danger. The safe disposal of recycling e-waste is a problem that is not going away.
- Computers use a large amount of energy; much of this energy is used in cooling electronic devices and systems. This is especially true in data centres where air conditioning is used to maintain a correct working environment.
- Energy supplies are expensive and so is important to make energy use efficient this can be achieved by reducing the heat created in new computer systems. In some cases, it is possible to reuse the waste heat from data centres to heat other parts of the building and so reduce the organisations overall energy usage and the impact on climate change.
- Computer technology can be used to reduce the damage on the environment by using automatic energy-reduction techniques within the workplace:
-Lights can be switched off automatically in individual offices when no one is in the room.
-Improved heating controls automatically take account of which rooms need to be heated and at what level.
-The use of low-energy devices for lighting is also making a contribution to energy reduction.
- Computer systems use energy . Data centres are particularly hungry for power. A lot of energy is wasted in the inefficient generation of heat which has to be removed from the equipment . Air conditioning in data centres use yet more energy. This is of concern to us all because energy supplies are finite and getting more expensive..