Computers and components

A computer is a machine, which has the ability to execute a set of instructions, a program, repeatedly and extremely rapidly. In this respect, a computer without programs is completely dull.

To make this work, a computer includes several key components:

1. A central processing unit (CPU) which people often qualify as the brain of a computer, although the only ability of a CPU is to make calculations on series of digits (0 or 1). An 8-bit CPU shall work on series of 8 bits called bytes. A 64-bit CPU shall work on series of 64 bits. The higher the frequency of a CPU, the higher the number of instructions this CPU can process in a period of time.
2. The persistent memory of a computer is essentially the hard drive, although there are many other means to persist data including optical drives, flash drives and solid state drives. Considering the large amounts of data we need to store, persistence relies on inexpensive but slow means.
3. To compensate for the slow persistent memory and avoid bottlenecks as the CPU requires more data to process instructions, computer architects have added expensive but fast random access memory (RAM). Basically, the fast RAM acts as a buffer between the fast CPU and the slow hard drive. The first time the CPU requires data, it obviously has to be read from the slow hard drive, but from then on it is available in fast RAM until space needs to be provided for new data. The more often the CPU can find data in RAM, the better is the overall computer performance.
4. The eyes, ears, mouth and members through which of a computer interacts with its environment are the input/output (I/O) devices. These I/O devices include monitors, keyboards, mice, printers, scanners, networks, …
5. The nervous system which connects all the components of a computer together and ensures the flow of data between them is called the bus. The bus is implemented in the motherboard, which provides connectors to plug the CPU, the RAM and the other components.

There is a misconception that the more powerful the CPU is, the better the computer is and if your computer is not fast enough you need a better CPU. Most of the time, from a pure hardware perspective, adding RAM is the key to improving computer performances.

Moore’s law states that the processing power of a CPU doubles every two years.

Kryder's Law states that the density of hard drives doubles annually.

Nielsen’s Law states that Internet bandwidth grows by 50% annually.

Accordingly, computers make tremendous progresses every year, and you are often better off buying a cheaper computer with the perspective to renew it in a couple of years rather than buying a more expensive one in view to keep it on a longer term.

NB: Add top manufacturers