Use of Computers
Computers are central to most of our work and leisure activities. They also play a part in many more important situations:
- aircraft navigation and control
- railway signalling
- many medical situations.
Medical computer systems include activities such as:
- record keeping
- diagnosis of diseases
- CAT (computer axial tomography) scans
- drug interactions
- use of search engines and expert systems to check symptoms
- robotic or remote surgery
- DNA sequencing
Mistakes in Design and Production
Reliability is expected when computers are comissioned.
Mistakes in the design and production of systems can lead to:
- down time
- expensive errors
- data loss
- compromised privacy
Reliability also refers to data integrity.
This relates to data being accurate and consistant throughout its life.
Data integrity also means that the stored data reflects real-world reality.
Database systems normally have rules that prevent inconsitent changes being made to the underlying data.
Data Integrity Risks
Data integrity can be compromised by:
- human errors when data is entered
- errors that occur when data is transmitted from one computer to another
- software bugs
- viruses and other malware
- hardware malfunctions
- natural disasters
Examples of ways to reduce risks to data integrity include:
- backing up data regularly
- controlling access to data via security mechanisms
- using validation rules to prevent input of invalid data
- using error detection and correction software when transmitting data
Reliability and Testing
Reliability is improved through testing. Testing is designed to uncover errors.
Testing can never be complete because:
- software is too complex
- testing is expensive
- testing is time consuming
There are huge numbers of pathways through modern systems so there are usually errors even in extensively tested systems.