Components of the Central Unit

Components of the Central Unit

A microprocessor (CPU, CPU )
This big chip is designed to execute the instructions of computer programs as quickly as possible. It calculates and copies the information. This is the central component of the computer. The microprocessor executes one instruction after the other, at a frequency set by a clock and measured in megahertz or gigahertz.

The frequency gives a first indication of the speed of the computer. To obtain a reliable estimate, it is still necessary to know the model of the microprocessor. Many electronic components heat up as long as they need to be ventilated.

The microprocessor is most often cooled by a heat sink surmounted by a fan. A fan is also integrated into the power supply of the housing to circulate fresh air. Other components (graphics card, motherboard …) may require a cooling system. The main quality of a good fan is to be quiet, which is achieved especially by a variable speed of rotation.

64 MB SDRAM RAM (RAM, RAM, DRAM, SDRAM, DDR-SDRAM, RDRAM )
It stores the information being processed by the microprocessor. It consists of chips arranged on small cards called barrettes. Its storage capacity (measured in megabytes or gigabytes) limits the number of information directly accessible to the microprocessor, so the processing capabilities of the computer.

The RAM must be fully electronic to track the frequency of the microprocessor, so it works only when the computer is running. The processing speed is influenced by the access time to the stored information (measured in megahertz or nanoseconds).

ASUS TXP4-X Motherboard, mainboard, MB
It is the largest electronic circuit of the computer. It is covered with connectors where other components are connected. The type and number of connectors determine which components can be used. Sometimes, graphics, sound, network or modem communication are integrated into the motherboard. Most functions are provided by one or two chips called chipset.

The latter therefore prioritize the performance of a motherboard. All information passes through the motherboard (and the chipset) through connections called a bus. The bit rates (measured in megabytes per second) of the various buses influence the speed of processing. Sometimes only the frequency (measured in megahertz) or the width (measured in bits) of a bus is given, the other quantity being invariable.

Matrox Millenium II Graphics card
It produces the images sent to the screen. It contains a clean random memory memorizing all the pixels of the displayed image, as well as the numerous textures used in the video games.

It also contains a graphics processor capable of animating images. The quality of interactive animations depends on the performance of this processor. The only currently reliable performance measure is to observe the speed and display quality of a test program, typically a game.

Quantum Atlas II Hard disk (HDD, hard drive, hard disk, HD, HDD )
Its utility is threefold. First, it memorizes the information magnetically, so even when the computer is off. Then it can memorize for the same price about a hundred times more data than RAM. Finally, it can be used by programs to overcome a lack of RAM, although it is at least a thousand times slower. Its storage capacity is measured in gigabytes.

Speed read/write is generally partially described by the average time of access (in milliseconds) by the rotational speed in revolutions per minute (abbreviated rpm) and by the type and transfer rate (or bitrate) of the bus connected to the motherboard (given in megahertz or megabytes per second).

The speed of the hard disk only influences the speed of the computer to the extent that the disk is used. It should be noted that it can be intensively used in case of lack of RAM.

ATX housing Case (tower, box, tower)
It contains all previously described components with slots for attaching the motherboard and various disk devices. It also contains a power supply unit including a fan and an electrical transformer.

Only low voltage currents supply the components. The case volume and the power of the power supply limit the number of usable devices. There are various forms of housing: the tower; the desktop box supporting the screen; mobile.

Main peripherals
Pioneer DR-U24XCD / DVD player/writer (CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-R, DVD-RW, DVD + R, DVD + RW)
CDs and DVDs are a means of storing economic and practical information. At first, it was only possible to read CDs. Then appeared recordable CDs (CD-R) and then re-recordable (CD-RW). Recording on a CD is called burning because it is impossible or at least difficult to erase a CD. The same evolution exists for DVDs.

The read/write/ rewrite speeds are given in multiples of the speed of a basic audio CD or DVD video respectively. Sometimes the average access time is also given. The performance of this device counts only in case of intensive use, typically engraving. The manufacturing quality of the reader (depending on the brand), as well as the medium, can have a noticeable effect on the success rate of copies and engravings.

Floppy disks have not changed since the early 1990s. They have a capacity of less than 2 MB and unreliable reliability. Floppy drives are also very slow and unreliable, but their price is minimal. Their main utility is to be used when turning on the computer without accessing the hard disk.

They also remain useful for exchanging information with old computers. The main variation is the national layout of the keys. There are several types of connection to the box, not necessarily compatible. Some keyboards are wireless.

Logitech Mouse
The main variation is the number of buttons and knobs. There are several types of connection to the box, not necessarily compatible. Some mice are wireless.

Commodore 1960 Screen (monitor, display, screen, CRT, LCD, TFT )
There are two main screen technologies: CRTs and Flat Panel Displays (LCDs, TFTs). CRTs tend to disappear because they are bulky.

The price depends primarily on the size, measured in inches on the diagonal. Then it depends on the general quality of the display (fidelity of colors, fineness of details, homogeneity of the rendering …) which is difficult to measure.

For CRTs, an additional measurable criterion is the stability of the image. It depends on the maximum refresh rate, measured in hertz for the vertical frequency (number of frames displayed per second) and in kilohertz for the horizontal frequency (number of lines displayed per second).

Sometimes the number of displayable pixels per second is given in megahertz instead of the horizontal frequency (one is deduced from the other). It is generally considered that a vertical frequency of 85 Hz is sufficient and that a higher frequency does not bring significant qualitative gain.

Flat screens have resolution fixed pixels. They do not always support all shades of colors. Their display has a response time, measured in milliseconds, which is important for rendering animations. Finally, the angle of vision under which the image remains clearly visible is limited and given in degrees.

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