Computer Systems

Computer Systems

1. Computer

   • A electronic, programmable data processing machine.

2. System

   • A collection of parts that work together for a defined purpose.

3. Definition: A collection of hardware and software that works together to achieve a set task.

4. For a system to be useful, it must produce something (output). It needs to receive and process in puts in order to produce outputs.

5. Outline of a system

   • Inputs: Systems receive inputs from outside.
     • Process: They process these inputs.
       • Storage
       • Output: They output the results of the processing.

6. Types of systems

   • Dedicated
     • A computer system with a dedicated purpose.
       • Microwave, calculators.
   • Embedded
     • A computer system with a dedicated function embedded as part of a complete device.
       • ATMs, mobile phones, thermostats.

7. Reliability

   • Is it life threatening?
   • How many people are effected?
   • Are they inconvenienced or more?
   • MTBF- Mean Time Between Failure.

8. Disaster recovery

   • On site and off site backups.
   • Disk mirroring (RAID)
   • Hardware sourcing plans.

9. Software development standards.

   • How to document what the system needs to do.
   • How to break the system into small parts that can be developed.
   • How to allocate staff to teams.
   • How to keep track of changes.
   • How to code programs.
   • How to test.
   • How to document the whole system.

10. Program coding standards.

    • Comments in the code.
    • Variable names and naming conventions.
    • Formatting code
    • Version names and numbers.

11. Benefits of Software standards.

    • Efficiency
      • Any member can edit any part of the code. without changing programming style.
    • Fewer errors
      • Standards result in accurate coding.
    • Easy to maintain
      • Structure is easy to understand and therefore easy to maintain.