Computer Systems Fundamentals

When the term computer is mentioned, you may think of a desktop or laptop computer.

There are many computers around us which are neither a desktop, nor laptop.

Examples include: TV, Alarm Clock, Microwave, Car and Printer among others

To understand why these can be classified as a computer, we need to understand the definition.

• A computer can accept input data
• A computer computes problems based on a set of instructions
• A computer can output information
• A computer stores data

It is worth noting that the first computers, for example the ENIAC, did not have the ability to store date.  In other words they did not have memory and had to be rewired for each problem.  During this time, the importance of having memory became clear.

So modern computers also have memory and can therefore, store data!

Reliability of a computer system is defined as the probability that a system will produce the correct outputs within a given timeframe.

Availability is the probability that a system is operational at a given time.

In other words, it is the amount of time a device is actually operating as the percentage of total time it should be operating.

A system with a high availability will be able to operate even when a fault occurs as it will disable the malfuctioning part and continue operating at a reduced capacity or sometimes even at the same capacity (depending on how the system has been designed and developed).

Maintainability or Serviceability is defined by how fast a system can be repaired or maintained.

The less time it takes to repair or maintain a system, the higher its availability.

Medicine
Radiation therapy
Robotic surgery
heart and lung machines

Recreation
Theme park rides

Transport
Cars, ships, trains, planes and space travel vehicles

Control Systems
Air traffic control systems
Airbag systems

• Development Process and Management
• Testing
• Legal Regulations and Standards