Characterization of the components of computers

Caractérisation des éléments constituants les ordinateurs

Characterization of the components of computers:

1- Presentation of the computer :

Understanding computer vocabulary is usually the main difficulty faced by potential buyers of personal computers. In fact, unlike a television, for which the selection criteria are quite limited, choosing a computer means choosing each element that makes it up and knowing its characteristics. This file is not intended to give meaning to all computer abbreviations (since many manufacturers have their own terminologies), but it seeks to help better understand the main components of a computer, explain the operation and give the main characteristics.

Any machine capable of handling binary information can be qualified as a computer, however, the term "computer" is sometimes confused with the concept of the personal computer (PC, an abbreviation of a personal computer), the type of computer most present on the market.

2- Computer constitution :

  • A computer is a set of modular electronic components, that is to say, components that can be replaced by other components possibly having different characteristics, capable of operating computer programs. We thus speak of “hardware” to designate all of the hardware elements of the computer and of “software” to designate the software part.
  • The hardware components of the computer are structured around the main board comprising a few integrated circuits and many electronic components such as capacitors, resistors, etc. All these components are soldered to the card and are connected by the 26 connections of the printed circuit and by a large number of connectors: this card is called the motherboard.
  • The motherboard is housed in a case (or chassis), with slots for storage devices on the front, as well as buttons to control the power of the computer and a number of lights to check the working condition of the device and the activity of the hard disks. On the rear side, the box has openings facing the expansion cards and the input-output interfaces connected to the motherboard.

Finally, the box houses a power supply unit (commonly called a power supply), responsible for supplying a stable and continuous electric current to all of the computer's components. The power supply is therefore used to convert the alternating current from the electrical network (220 or 110 Volts) into a DC voltage of 5 Volts for computer components and 12 Volts for certain internal peripherals (disks, CD-ROM drives, ...). The power supply is characterized by its power, which conditions the number of peripherals that the computer is capable of supplying. The power of the power supply is generally between 200 and 450 Watts.

We call "central unit", the assembly consisting of the housing and the elements it contains. Elements external to the central unit are called peripherals.

The central unit must be connected to a set of external devices. A computer is generally composed of at least a central unit, a screen (monitor) a keyboard, and a mouse, but it is possible to connect a wide variety of peripherals on the input-output interfaces.

The processor is divided into two parts, the control unit, and the processing unit:

  • The controls unit is responsible for reading from memory and decoding the instructions;
  • The processing unit also called the Arithmetic and Logic Unit (U.A.L.), executes the instructions which manipulate the data.

Central memory: unit used to store programs and data.

Main memory: unit used to store programs and data.

Input / Output devices: communication units with the exterior.

Bus: grouping of wires allowing the transit of information (Central communication artery).

3- The different components of the motherboard

The chipset :

The chipset (translate set of components or set of circuits) is an electronic circuit responsible for coordinating the exchange of data between the various components of the computer (processor, memory; ...). Since the chipset is integrated into the motherboard, it is important to choose a motherboard incorporating a recent chipset in order to optimize the possibilities of the scalability of the computer.

Some chipsets sometimes integrate a graphics chip or an audio chip, which means that it is not necessary to have a graphics card or a sound card. However, it is sometimes advisable to deactivate (when possible) in the BIOS configuration and on quality expansion cards in the slots provided for this purpose.

CMOS clock and battery :

The real-time clock (denoted RTC, for Real-Time Clock) is a circuit responsible for synchronizing system signals. It consists of a crystal which, by vibrating, gives impulses (called clock ticks) in order to clock the system. Called clock frequency (expressed in MHz) the number of crystal vibrations per second, that is to say, the number of clock ticks emitted per second.

When the computer is turned off, power stops supplying power to the motherboard. Or, when the computer is reconnected, the system is always on time. An electronic circuit, called CMOS (Complementary Metal-Oxide Semiconductor, sometimes called BIOS CMOS), stores certain information on the system, such as time system date, and some essential parameters of the system.

The CMOS is continuously powered by a battery (in button cell format) or a battery located on the motherboard. Thus, information about the hardware installed in the computer (such as the number of tracks, sectors of each hard drive) is kept in the CMOS. Since CMOS is slow memory, some systems sometimes copy the contents of CMOS into RAM (fast memory), the term "shadow shadow" is used to describe this process of copying into RAM.


The BIOS (Basic Input / Output System) is the basic program serving as an interface between the operating system and the motherboard. The BIOS is stored in a ROM (read-only memory, that is to say, a read-only memory), so it uses the data provided in the CMOS to know the hardware configuration of the system.

Processor support :

The processor (also called a microprocessor) is the brain of the computer. It executes program instructions using a set of instructions. The processor is characterized by its frequency, which is to say the rate at which it executes the instructions. Thus, a processor clocked at 800 MHz will roughly perform 800 million operations per second.

The motherboard has a slot (sometimes several in the case of multiprocessor motherboards) to accommodate the processor, called the processor socket. On distinguishing two categories of supports:

• Slot (in French slot): this is a rectangular connector in which the processor is inserted vertically

• Socket (in French socket): it is a square connector with a large number of small connectors on which the processor is directly plugged

Within these two large families, there are different versions of the support, depending on the type of processor. It is essential, whatever the support, to gently connect the processor so as not to have an order of its pins (it has several). In order to facilitate the insertion of the wires, support called ZIF (Zero Insertion Force) has been created. The ZIF supports have a small lever, which is therefore raised, allows the processor to be inserted without any pressure, and as soon as it is lowered, keeps the processor on its support.

RAM connectors :

Random Access Memory (RAM) is used to store information during the computer's operating time; its content is however destroyed as soon as the computer is turned off or on, unlike mass memory such as then the hard drive, capable of keeping information even when it is turned off. We speak of “volatility” to designate this phenomenon.

4- Extension connectors :

Expansion slots are receptacles in which it is possible to insert expansion cards, that is to say, cards offering new features or better performance to the computer. There are several kinds of connectors :

  • ISA connector (Industry Standard Architecture): for connecting ISA cards, the slowest operating in 16-bit
  • VLB connector (Vesa Local Bus): Bus formerly used to connect graphics cards
  • PCI connector (Peripheral Component Interconnect): allowing to connect PCI cards, much faster than ISA cards and working in 32-bit
  • AGP (Accelerated Graphic Port) connector: a quick connector for graphics cards.
  • PCI Express (Peripheral Component Interconnect Express) connector: faster bus architecture than AGP and PCI buses.
  • AMR connector (Audio Modem Riser): this type of connector allows mini-cards to be connected to PCs when equipped

Input-output connectors :

The motherboard has a number of input-output connectors grouped together on the "rear panel".

Most motherboards offer the following connectors :

  • Serial port, allowing to connect old peripherals;
  • Parallel port, allowing in particular to connect old printers;
  • USB ports (1.1, low speed, or 2.0, high speed), allowing connection of newer peripherals
  • RJ45 connector (called LAN or ethernet port) used to connect the computer to a network corresponding to the integration of the card in the motherboard
  • VGA connector (called SUB-D15), used to connect a screen. This connector corresponds to the integrated graphics card;
  • Audio sockets (Line-In, Line-Out, and microphone), allowing you to connect speakers or a hi-fi system, as well as a microphone. This connector corresponds to the integrated sound card.

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