A computer is a machine for manipulating data according to a list of instructions. It consists of the hardware – the physical components, and the software – a variety of programs.
The CPU is the brain of a computer and it usually consists of:

• An Arithmetic and Logic Unit (ALU) – performing basic arithmetical and logical operations,
• A control and timing unit – ensuring sequencing and coordination of operations,
• Memory – that is small and uses high speed that temporarily stores and controls information. The memory is composed of registers that are often only 32 bits.

---

The CPU executes various programs by following the programmed instructions which are first examined and then executed in a sequential manner. It uses three buses for its internal communications with its built-in memory: one address bus, one data bus, and one control bus. When multiple tasks share common resources, such as the same CPU, it can be defined as” multitasking”. Multitasking gives the appearance of running several programs at the same time as the CPU switches rapidly between each program in turn.
When two or more CPUs are used with a single computer, the operation is called “multiprocessing”. It is a hardware solution which main advantage is that it the computer’s speed will be greatly increased as it will be able to process larger amounts of information.