A computer is a system comprising several electronic items that work together to achieve a task in a period of time that is much shorter than if done manually. It basically receives information (text, pictures, audio files ...) and then processes it and put in a format that is easy to understand and use.
When used properly, a computer can handle large amount of information and can therefore be very efficient. Computers may be used to process, store, transform, retrieve, generate, analyze and present large amount of information.
The most important electronic component in a computer is the central processing unit (CPU) which in turn comprises the Arithmetic Logical Unit (ALU) that does the actual arithmetic and logical computations. Data and instructions are held in memory ready to be transported through the control and data bus to and from the CPU and also to the input/output peripherals such as monitors, printers, scanners, digital cameras and speakers.
Fig. 1 - Computer Architecture
The CPU uses the address bus to carry the addresses of the memory location or I/O devices it is accessing. The control bus is used by the CPU to carry control signals between the CPU and other components such as input/output peripherals in the computer.
The hardware is made up of all the physical parts such as CPU, memory, monitor, printer ... and the software is the set of all programs (set of instructions) that helps the computer do what it is supposed to do.
All operations in a computer are done on binary numbers represented using 1s and 0s only. Physically, the 1 is represented by a swicth that is "ON" and a 0 is represented by a switch that is "OFF". These are done using electronic devices that work at a very high speed. From the keyboard, we input letters and numbers in decimal form but all these are translated into streams of 1s and 0s using codes and then processed.