Fundamentals of Computer Systems
- A computer is an electronic, programmable data processing machine.
- A system is a collection of parts working together for a purpose, think about it like an organ system working together to keep you alive.
- A computer system is a collection of hardware and software that works together to achieve some data processing task
Systems receive inputs from the outside. They process these inputs. They output the results of the processing.
This is an outline of a system:
Inputs - Processes - Outputs
A system is separated from the outside world by a system boundary.
These boundaries are often called interfaces.
Fundamentals of Computer Systems
Importance of Computer Systems
Most aspects of our lives are affected by computer systems.
They have led to:
- Improved quality in manufacturing - robotic machinery is more accurate
- Cheaper manufacturing - don't have to pay the machines wages and allows 24/7 working
- Faster to access information - jobs can be done quicker with computer systems to help
- Better decision making - with lots of organised, available facts decision can be better informed
- New ways of doing business - more buying online, more choice
- New ways of communicating - email, SMS, mobile phones
Example of a computer system you may have used:
Washing machine, Inputs: temperature, water levels, dirtiness, Outputs: timer Processing: check values, determine washing parameters
Types of Computer Systems
General Purpose Systems
- Personal computers such as desktops, laptops, and smartphones
- They're designed to perform multiple tasks
- Various applications (apps) can be loaded so they can be used for different purposes
- Specially produced to perform a single function or set of functions
- For example, a ticket machine at a train station it performs a single set of instructions
- Computer systems that are part of a larger system
- Can be simple and can be complex
- They include some portable devices such as digital watches, satnavs, cameras
- Computers designed to behave like a human expert
- They have a knowledge base, an inference engine, and an interface
- They are commonly used for diagnosing diseases, finding faults in machinery
Computer might have a role in life or death situations:
- Aircraft navigation and control
- Railway signalling
- Many medical situations
Medical computers have important activities:
- Record keeping
- Diagnosis of diseases
- Drug interactions
Mistakes in the design and production of systems can lead to:
- Down time
- Expensive errors
- Data loss
- Compromised privacy
- This relates to data being accurate and consistent throughout its life
- Also means that the data store reflects real-world reality
- Database systems usually have rules that prevent inconsistent changes being made
Data Integrity can be Compromised by:
- Human errors when data is entered
- Errors that occur when data is transmitted
- Software bugs
- Hardware malfunctions
Ways to reduce risks:
- Backing up data regularly
- Controlling access to data
- Using validation rules
Reliability and Testing
Reliability is improved by thorough testing. Testing is designed to uncover errors.
Testing can never be complete:
- Software is so complex
- Testing is expensive
- Testing is time-consuming
There are huge numbers of pathways through most modern systems so there are usually errors even in extensively tested systems.
There are various categories of standards
In computing, standards exist for:
- Programming languages
- Operating systems
- Data formats
- Communication protocols
- Electrical interfaces
Originally there were no standards. This was a problem.
Standards are important because they:
- Enable equipment from different manufacturers to work together
- Make learning new systems easier because they have similar characteristics
- Minimise waste
- Brings costs down by opening markets to competition
De facto standards
Standards developed over time from common use.
They make it so files and systems can be used by anyone
- The QWERTY keyboard
- Microsoft Word
- They are owned by an organisation.
- The ensure compatibility between the companies products
- They are widely used but not approved by an independent standards body
- Because products have the similar interfaces it makes learning and getting to grips with the product easier.
- publicly available
- produced collaboratively
- not dominated by any one interest group
- not for a profit and available free of charge or at a small cost
- sufficiently detailed
Open standards ensure that access to resources is not dependent upon:
- a single application
- a particular hardware platform
Some examples of open standards:
Ethical and Legal Issues
An ethical act is one that is morally right, and a legal act is one that doesn't break any laws.
Computers have laws about:
- data security
- access to sensitive data
The data protection act covers any data about a living and identifiable individual.
Typical data protection laws include provisions that organisations must:
- allow people to view data held about them
- correct information when requested
- only collect data for a specified and lawful purpose
- not use data in any way that may potentially cause damage or distress
Old computers which are no longer in use have to be disposed of. They contain toxic materials such as:
- flame retardants
E-waste is often shipped to developing countries where there are few safeguards. Much waste goes to landfills, where toxic chemicals can leak into the soil. Old computers contain a lot of plastics, for example in circut boards. When these are burnt they release dangerous chemicals such as dioxins.