Graphic adapters cards. What is a video card? Graphics adapter
Video card.
Working with graphics is one of the most difficult tasks you have to solve modern computer. Complex images, millions of colors and shades... Therefore, it is not surprising that for this work you actually have to install a second powerful processor. The video card is just the first and main of these “vicars”, when choosing which you need to be especially careful and attentive.
Since all modern video cards are capable of quickly and efficiently processing two-dimensional graphics, when choosing a video card, most users first of all pay attention to its ability to work with three-dimensional graphics. The idea that this is the most important advantage of a video card was successfully drummed into the minds of users by three last year, so it should not be surprising that even a buyer who is not interested in games is increasingly choosing a fashionable (and expensive) card for gamers for his computer.
Creating a three-dimensional, realistic image is not an easy task. In fact, the video card has to perform several complex operations: build a “frame” of each three-dimensional object, cover it with suitable pieces of the image - textures that imitate foliage, clothing, rocks, earth, etc. And most importantly, be ready at any moment, obeying the player’s wishes , show it from any point of view: from above, from the side and sometimes even from below! Moreover, it is important not only to show the object from four sides, but also, what is most difficult, to recreate its real life on the screen. volumetric model. If you move a centimeter, the three-dimensional object will look slightly different. In this case, the video card must calculate not only two spatial coordinates for each pixel, but also a third, which characterizes the distance of the object from the observer. But recreating volume is not the most difficult task. After all, even the most voluminous figure will look pale and colorless if you do not apply a texture to it, that is, simply color it with the help of many colored objects. Imagine that you have in your hands a kind of doll doll on which you can put any design - this is exactly the process that happens in games. To store textures, the video card requires a large amount of its own random access memory(min 512 MB).
For example, anti-aliasing of image contours, imitation of fog, flames, ripples on the water surface, reflection in a mirror, shadows and many others. To support gaming special effects, a special “transformation and lighting unit” (T&L) is built into the video card processor, which allows you to get simply fantastic quality of the game image, and at the same time increases the cost of the card by several tens of dollars.
Finally, another range of tasks that your video card is designed to solve is processing multimedia information. Many cards today support displaying images on a television screen or, conversely, receiving images from external source- video camera, VCR or TV antenna(these operations are performed by the video input and TV tuner, respectively). In addition, a modern video card also has to deal with decoding the “compressed” video signal coming from DVDs.
Device.
A modern video card consists of the following parts:
GPU
The graphics processor (Graphics processing unit (GPU) is a graphics processing unit) is responsible for calculating the output image, relieving you of this responsibility CPU, performs calculations for processing 3D graphics commands. Is the basis graphics card, the performance and capabilities of the entire device depend on it. Modern GPUs in complexity they are not much inferior to the central processor of a computer, and often surpass it both in the number of transistors and in computing power, thanks to a large number universal computing units. However, the previous generation GPU architecture usually involves the presence of several information processing units, namely: a 2D graphics processing unit, a 3D graphics processing unit, in turn, usually divided into a geometric kernel (plus a vertex cache) and a rasterization unit (plus a texture cache ) and etc.
All modern video cards are based on graphics Nvidia processors and AMD (ATi)
Video controller
The video controller is responsible for generating images in video memory, giving RAMDAC commands to generate scan signals for the monitor and processing requests from the central processor. In addition, there is usually an external data bus controller (for example, PCI or AGP), an internal data bus controller, and a video memory controller. The width of the internal bus and video memory bus is usually larger than the external one (64, 128 or 256 bits versus 16 or 32); many video controllers also have RAMDAC built in. Modern graphics adapters (ATI, nVidia) usually have at least two video controllers that operate independently of each other and simultaneously control one or more displays each.
Video ROM
Video ROM (Video ROM) is a read-only memory device (ROM) in which the BIOS of the video card is written, screen fonts, service tables, etc. ROM is not used directly by the video controller - only the central processor accesses it.
BIOS ensures the initialization and operation of the video card before loading the main operating system, sets all low-level parameters of the video card, including operating frequencies and supply voltages of the graphics processor and video memory, memory timings. Also, VBIOS contains system data that can be read and interpreted by the video driver during operation (depending on the method used to separate the responsibilities between the driver and the BIOS). On many modern maps electrically reprogrammable ROMs (EEPROM, Flash ROM) are installed, allowing the video BIOS to be rewritten by the user himself using special program.
Video memory
Video memory acts as a frame buffer, which stores the image generated and constantly modified by the graphics processor and displayed on the monitor screen (or several monitors). Video memory also stores intermediate image elements invisible on the screen and other data. Video memory comes in several types, differing in access speed and operating frequency. Modern video cards are equipped with DDR, GDDR2, GDDR3, GDDR4 and GDDR5 memory. It should also be borne in mind that in addition to the video memory located on the video card, modern graphics processors usually use part of the total system memory computer, direct access to which is provided by the video adapter driver via the AGP or PCIE bus. When using the Uniform Memory Access architecture, part of the computer's system memory is used as video memory.
A digital-to-analog converter (DAC; RAMDAC - Random Access Memory Digital-to-Analog Converter) is used to convert the image generated by the video controller into color intensity levels supplied to analog monitor. The possible color range of the image is determined only by the RAMDAC parameters. Most often, a RAMDAC has four main blocks: three digital-to-analog converters, one for each color channel(red, green, blue - RGB), and SRAM for storing gamma correction data. Most DACs have a bit resolution of 8 bits per channel - this results in 256 brightness levels for each primary color, which gives a total of 16.7 million colors (and due to gamma correction, it is possible to display the original 16.7 million colors in much more color space). Some RAMDACs have a capacity of 10 bits for each channel (1024 brightness levels), which allows you to immediately display more than 1 billion colors, but this feature is practically not used. To support a second monitor, a second DAC is often installed. It is worth noting that monitors and video projectors connected to digital DVI output video cards use their own digital-to-analog converters to convert the digital data stream and do not depend on the characteristics of the video card’s DAC.
Connector
Initially, video adapters were equipped with a 9-pin (15-) D-Sub connector. Occasionally there was also a coaxial Composite Video connector, allowing you to output black and white image to a television receiver or monitor equipped with a low-frequency video input.
Currently, boards are equipped with DVI or HDMI connectors, or DisplayPort in the amount of one to three (some ATi video cards latest generation equipped with six connectors). DVI ports and HDMI are evolutionary stages of development of the video signal transmission standard, so adapters can be used to connect devices with these types of ports. DVI-I port also includes analog signals, allowing you to connect a monitor via an adapter to the old D-SUB connector (DVI-D does not allow this). DisplayPort allows you to connect up to four devices, including audio devices, USB hubs and other input/output devices.
Cooling system
The cooling system is designed to maintain temperature regime video processor and (often) video memory within acceptable limits.
Characteristics of video cards
The memory bus width is measured in bits - the number of bits of information transferred per clock cycle. Important parameter in card performance.(128 - 256)
The amount of video memory, measured in megabytes, is the amount of the video card’s own RAM. Larger volume does not always mean greater performance (512 - 2048 MB)
Video cards integrated into the set system logic motherboard or being part of the CPU, usually do not have their own video memory and use part of the computer’s RAM (UMA - Unified Memory Access) for their needs.
Core and memory frequencies are measured in megahertz; the higher, the faster the video card will process information.
Texture and pixel fill rate, measured in million pixels per second, shows the amount of information displayed per unit of time.
Video card.
Working with graphics is one of the most difficult tasks a modern computer has to solve. Complex images, millions of colors and shades... Therefore, it is not surprising that for this work you actually have to install a second powerful processor in your computer. The video card is just the first and main of these “vicars”, when choosing which you need to be especially careful and attentive.
Since all modern video cards are capable of quickly and efficiently processing two-dimensional graphics, when choosing a video card, most users first of all pay attention to its ability to work with three-dimensional graphics. The idea that this is the most important advantage of a video card has been successfully drummed into the minds of users for the last three years, so it is not surprising that even a buyer who is not interested in games is increasingly choosing a fashionable (and expensive) card for gamers for his computer.
Creating a three-dimensional, realistic image is not an easy task. In fact, the video card has to perform several complex operations: build a “frame” of each three-dimensional object, cover it with suitable pieces of the image - textures that imitate foliage, clothing, rocks, earth, etc. And most importantly, be ready at any moment, obeying the player’s wishes , show it from any point of view: from above, from the side and sometimes even from below! Moreover, it is important not only to show the object from four sides, but also, what is most difficult, to recreate its real, three-dimensional model on the screen. If you move a centimeter, the three-dimensional object will look slightly different. In this case, the video card must calculate not only two spatial coordinates for each pixel, but also a third, which characterizes the distance of the object from the observer. But recreating the volume is not the most difficult task. After all, even the most voluminous figure will look pale and colorless if you do not apply a texture to it, that is, simply color it with the help of many colored objects. Imagine that you have in your hands a kind of doll doll on which you can put any design - this is exactly the process that happens in games. To store textures, the video card requires a large amount of its own RAM (min. 512 MB).
For example, anti-aliasing of image contours, imitation of fog, flames, ripples on the water surface, reflection in a mirror, shadows and many others. To support gaming special effects, a special “transformation and lighting unit” (T&L) is built into the video card processor, which allows you to get simply fantastic quality of the game image, and at the same time increases the cost of the card by several tens of dollars.
Finally, another range of tasks that your video card is designed to solve is processing multimedia information. Many cards today support displaying images on a television screen or, conversely, receiving images from an external source - a video camera, VCR or television antenna (these operations are performed by the video input and TV tuner, respectively). In addition, a modern video card also has to deal with decoding the “compressed” video signal coming from DVD discs.
Device.
A modern video card consists of the following parts:
GPU
The graphics processor (Graphics processing unit (GPU) - graphic processing unit) is engaged in calculations of the output image, relieving the central processor of this responsibility, and makes calculations for processing 3D graphics commands. It is the basis of the graphics card; the performance and capabilities of the entire device depend on it. Modern graphics processors are not much inferior in complexity to the computer's central processor, and often surpass it both in the number of transistors and in computing power, thanks to the large number of universal computing units. However, the previous generation GPU architecture usually involves the presence of several information processing units, namely: a 2D graphics processing unit, a 3D graphics processing unit, in turn, usually divided into a geometric kernel (plus a vertex cache) and a rasterization unit (plus a texture cache ) and etc.
All modern video cards are based on Nvidia and AMD (ATi) GPUs
Video controller
The video controller is responsible for generating images in video memory, giving RAMDAC commands to generate scan signals for the monitor and processing requests from the central processor. In addition, there is usually an external data bus controller (for example, PCI or AGP), an internal data bus controller, and a video memory controller. The width of the internal bus and video memory bus is usually larger than the external one (64, 128 or 256 bits versus 16 or 32); many video controllers also have RAMDAC built in. Modern graphics adapters (ATI, nVidia) usually have at least two video controllers that operate independently of each other and simultaneously control one or more displays each.
Video ROM
Video ROM (Video ROM) is a read-only memory device (ROM) in which the video card BIOS, screen fonts, service tables, etc. are written. The ROM is not used directly by the video controller - only the central processor accesses it.
BIOS ensures the initialization and operation of the video card before loading the main operating system, sets all low-level parameters of the video card, including operating frequencies and supply voltages of the graphics processor and video memory, memory timings. Also, VBIOS contains system data that can be read and interpreted by the video driver during operation (depending on the method used to separate the responsibilities between the driver and the BIOS). Many modern cards are equipped with electrically reprogrammable ROMs (EEPROM, Flash ROM), which allow the video BIOS to be rewritten by the user using a special program.
Video memory
Video memory acts as a frame buffer, which stores the image generated and constantly modified by the graphics processor and displayed on the monitor screen (or several monitors). Video memory also stores intermediate image elements invisible on the screen and other data. Video memory comes in several types, differing in access speed and operating frequency. Modern video cards are equipped with DDR, GDDR2, GDDR3, GDDR4 and GDDR5 memory. It should also be borne in mind that in addition to the video memory located on the video card, modern graphics processors usually use in their work part of the general system memory of the computer, direct access to which is organized by the video adapter driver via the AGP or PCIE bus. When using the Uniform Memory Access architecture, part of the computer's system memory is used as video memory.
Digital-to-analog converter
A digital-to-analog converter (DAC; RAMDAC - Random Access Memory Digital-to-Analog Converter) is used to convert the image generated by the video controller into color intensity levels supplied to an analog monitor. The possible color range of the image is determined only by the RAMDAC parameters. Most often, RAMDAC has four main blocks: three digital-to-analog converters, one for each color channel (red, green, blue - RGB), and SRAM for storing gamma correction data. Most DACs have a bit depth of 8 bits per channel - this results in 256 brightness levels for each primary color, which gives a total of 16.7 million colors (and due to gamma correction, it is possible to display the original 16.7 million colors in a much larger color space) . Some RAMDACs have a capacity of 10 bits for each channel (1024 brightness levels), which allows you to immediately display more than 1 billion colors, but this feature is practically not used. To support a second monitor, a second DAC is often installed. It is worth noting that monitors and video projectors connected to the digital DVI output of a video card use their own digital-to-analog converters to convert the digital data stream and do not depend on the characteristics of the video card’s DAC.
Connector
Initially, video adapters were equipped with a 9-pin (15-) D-Sub connector. Occasionally, a coaxial Composite Video connector was also present, allowing a black-and-white image to be output to a television receiver or monitor equipped with a low-frequency video input.
Currently, boards are equipped with one to three DVI or HDMI connectors, or DisplayPort (some latest generation ATi video cards are equipped with six connectors). DVI and HDMI ports are evolutionary stages in the development of the video signal transmission standard, so adapters can be used to connect devices with these types of ports. The DVI-I port also includes analog signals, allowing you to connect a monitor via an adapter to the old D-SUB connector (DVI-D does not allow this). DisplayPort allows you to connect up to four devices, including audio devices, USB hubs and other input/output devices.
Cooling system
The cooling system is designed to maintain the temperature of the video processor and (often) video memory within acceptable limits.
Characteristics of video cards
The memory bus width is measured in bits - the number of bits of information transferred per clock cycle. An important parameter in card performance.(128 - 256)
The amount of video memory, measured in megabytes, is the amount of the video card’s own RAM. Larger volume does not always mean greater performance (512 - 2048 MB)
Video cards that are integrated into the system logic set of the motherboard or are part of the CPU usually do not have their own video memory and use part of the computer’s RAM (UMA - Unified Memory Access) for their needs.
Core and memory frequencies are measured in megahertz; the higher, the faster the video card will process information.
Texture and pixel fill rate, measured in million pixels per second, shows the amount of information displayed per unit of time.
Nowadays, almost all computers are equipped with a discrete video card. By using of this device an image visible on the monitor screen is created. This component is far from simple, but consists of many parts that form a single working system. In this article we will try to talk in detail about all the components modern video card.
Today we will look at modern discrete video cards, because integrated ones have a completely different configuration and, basically, they are built into the processor. The discrete graphics adapter is presented as printed circuit board, which is inserted into the corresponding expansion connector. All components of the video adapter are located on the board itself in in a certain order. Let's take a closer look at all the components.
GPU
At the very beginning, we need to talk about the most important part in a video card - the GPU (graphics processing unit). From of this component The performance and power of the entire device depends. Its functionality includes processing graphics-related commands. The GPU takes over execution certain actions, thereby reducing the load on the CPU, freeing up its resources for other purposes. The more modern the video card, the greater the power of the GPU installed in it; it can even exceed the central processor due to the presence of many computing units.
Video controller
The video controller is responsible for generating the image in memory. It sends commands to the digital-to-analog converter and processes the CPU commands. A modern card has several built-in components: a video memory controller, an external and internal data bus. Each component operates independently of each other, allowing simultaneous control display screens.
Video memory
To store images, commands and intermediate elements not visible on the screen, a certain amount of memory is required. Therefore, each graphics adapter has a constant amount of memory. It happens different types, differing in their operating speed and frequency. Type GDDR5 on this moment is the most popular, used in many modern cards.
However, it is also worth considering that in addition to the memory built into the video card, new devices also use the RAM installed in the computer. To access it use special driver via PCIE and AGP bus.
Digital-to-analog converter
The video controller produces an image, but it must be converted into the desired signal with certain color levels. This process performs the DAC. It is built in the form of four blocks, three of which are responsible for RGB conversion(red, green and Blue colour), A last block stores information about the upcoming brightness and gamma correction. One channel operates at 256 brightness levels for individual colors, and in total the DAC displays 16.7 million colors.
Read Only Memory
The ROM stores the necessary screen elements, information from the BIOS and some system tables. The video controller is not used in any way with the permanent storage device; it is accessed only by the CPU. It is thanks to the storage of information from BIOS video card starts and functions even before the OS is fully loaded.
Cooling system
As is known, the processor and graphics card They are the hottest components of a computer, so they require cooling. If in the case of a CPU the cooler is installed separately, then most video cards have a radiator and several fans built into them, which allows you to save relatively low temperature at heavy loads. Some powerful modern cards get very hot, so a more powerful water system is used to cool them.
Video card
Video card (also known as graphics card, graphics card, video adapter) (eng. videocard)- a device that converts an image stored in the computer's memory into a video signal for the monitor.
Usually the video card is an expansion card and is inserted into connector extensions, universal (ISA, VLB,PCI,PCI-Express) or specialized ( AGP), but it can also be built-in (integrated).
Modern video cards are not limited simple conclusion images, they have built-in graphics microprocessor, which can produce additional processing, relieving the central CPU computer. For example, all modern NVIDIA video cards and AMD( ATi) support OpenGL applications in hardware.
Video cards have following standards
On PS/2 computers, most of the video adapter circuitry is located on system board. This video adapter contains everything electronic circuits, necessary to support the VGA specification, on one full-size board with an 8-bit interface.
BIOS VGA is a program designed to manage VGA circuits. Through BIOS programs can initiate some VGA procedures and functions without accessing the adapter.
All VGA equipment provides display of up to 256 shades on the screen from a palette of 262,144 colors (256 KB). An analog monitor is used for this.
If problems arise when booting the system, it boots into safe mode, where the default is VGA adapter in 640x480 mode, 16 colors.
SuperVGA Super Video Graphics Array. Provides higher resolution than the VGA standard. Supports operating modes with resolutions of 800:600, 1024:768, 1280:1024 pixels (or more) with simultaneous display of 2 in 4, 8, 16, 32 degrees of color.
With adapters SVGA various models from different manufacturers you can communicate through a single software interface VESA
Existing standard VESA on boards SVGA provides the use of almost all common image formats and color coding options, up to a resolution of 1280x1024 pixels with 16,777,216 shades (24-bit color coding).
A modern video card consists of the following parts:
Bios (Basic Input/Output System - basic system I/O). The video adapter BIOS contains basic commands, which provide an interface between the video adapter hardware and software. BIOS that can be modified using software, called flash BIOS.
Graphics processing unit (graphics processing unit)- deals with calculations of the output image, relieving the central processor of this responsibility, and makes calculations for processing three-dimensional graphics commands. It is the basis of the graphics card; the performance and capabilities of the entire device depend on it. Modern graphics processors are not much inferior in complexity to the computer's central processor, and often surpass it both in the number of transistors and in computing power, thanks to the large number of universal computing units. However, the architecture GPU The previous generation usually involves the presence of several information processing units, namely: a 2D graphics processing unit, a 3D graphics processing unit, in turn, usually divided into a geometric kernel (plus a vertex cache) and a rasterization unit (plus a texture cache), etc.
Video controller- responsible for forming an image in video memory, gives commands RAMDAC to generate scanning signals for the monitor and processes requests from the central processor. In addition, there is usually an external data bus controller (for example, PCI or AGP), internal data bus controller and video memory controller. The width of the internal bus and video memory bus is usually larger than the external one (64, 128 or 256 bits versus 16 or 32); many video controllers also have built-in RAMDAC. Modern graphics adapters ( ATI, nVidia) usually have at least two video controllers that operate independently of each other and simultaneously control one or more displays each.
Video memory- acts as a frame buffer in which the image is stored, generated and constantly changed by the graphics processor and displayed on the monitor screen (or several monitors). Video memory also stores intermediate image elements invisible on the screen and other data. Video memory comes in several types, differing in access speed and operating frequency. Modern video cards are equipped with memory type DDR, DDR2, GDDR3, GDDR4 and GDDR5. It should also be borne in mind that in addition to the video memory located on the video card, modern graphics processors usually use part of the computer’s general system memory in their work, direct access to which is organized by the video adapter driver via the bus AGP or PCIE.
Digital-to-analog converter (DAC, RAMDAC - Random Access Memory Digital-to-Analog Converter)- serves to convert the image generated by the video controller into color intensity levels supplied to an analog monitor.
Video ROM- a permanent storage device in which video BIOS, screen fonts, service tables, etc. are written. ROM is not used directly by the video controller - only the central processor accesses it. The video BIOS, stored in ROM, ensures initialization and operation of the video card before loading the main operating system, and also contains system data that can be read and interpreted by the video driver during operation (depending on the method used sharing of responsibilities between the driver and the BIOS). Many modern cards use electrically reprogrammable ROMs ( EEPROM, Flash ROM), allowing the video BIOS to be rewritten by the user himself using a special program.
Cooling system-designed to maintain the temperature of the video processor and video memory within acceptable limits.
The signals supplied to the monitor come from the video adapter built into the system or connected to the computer.
There are three ways to connect computer systems to a CRT or LCD monitor:
Separate video cards. This method, which requires AGP or PCI expansion slots, provides the highest level of efficiency and maximum operational flexibility in choosing the amount of memory and capabilities required (Figure 17);
A graphics chipset built into the motherboard. The lowest cost graphics configuration and fairly low efficiency, especially for 3D games or graphics applications. Resolution and color rendering capabilities are lower than when using separate video adapters, and the amount of memory is almost impossible to change;
Figure 15 – Appearance video adapter
The following components are required for the video adapter to work:
BIOS (Basic Input/Output System - basic input/output system);
The video adapter BIOS, like the system BIOS, is stored in a ROM chip; it contains basic commands that provide the interface between the video adapter hardware and the software. The program that accesses the video adapter's BIOS functions can be a standalone application, operating system or system BIOS. Accessing BIOS functions allows you to display monitor information during POST and begin booting the system before loading any other driver software from disk. The BIOS of a stand-alone video adapter does not depend on the motherboard BIOS. When using a video adapter built into the system logic set, the BIOS of the motherboard and the video adapter are common.
Graphics processor - video accelerator chip with limited set functions. This architecture, used in many video adapters presented on the modern computer market, assumes that the electronic circuits of the video adapter solve algorithmically simple, but time-consuming tasks. In particular, the electronic circuits of the video adapter construct graphic primitives - straight lines, circles, etc., while the computer's central processor is left to construct the image, decompose it into components and send instructions to the video adapter, for example: draw a rectangle of a certain size and color.
Modern graphics systems also use a three-dimensional graphics processor (3D graphics), which is used in almost all video adapters optimized for computer games, as well as in most of the most common video cards. The 3D graphics processor, which is a 3D graphics processing unit, is located in the accelerator chipset and is used to generate polygon images, create lighting effects, and draw halftones.
Video memory. When forming an image, the video adapter accesses memory. The memory capacity on the video adapter (video memory) can vary: from 4 to 512 MB and higher. Additional memory does not increase the speed of the video adapter, but it allows you to increase image resolution and/or the number of reproduced colors. Video adapters built into the system logic use a portion of the RAM that is strictly limited in the BIOS settings.
The amount of memory required to create a mode with given resolution and the number of colors is calculated as follows. Each pixel in an image requires a certain amount of memory to encode, and the total number of pixels is determined by the given resolution. For example, at a resolution of 1,024x768, the screen displays 786,432 pixels.
If this resolution supported only two colors, then only one bit of memory would be needed to display each pixel, with a bit with a value of 0 defining a black point and a bit with a value of 1 defining a white point. By allocating 24 bits of memory to each pixel, more than 16.7 million colors can be displayed, since the number of possible combinations for a 4-bit binary number is 16,777,216 (i.e. 2 24). By multiplying the number of pixels used at a given screen resolution by the number of bits required to display each pixel, we obtain the amount of memory required to generate and store images in this format. Below is an example of such calculations:
1,024 × 768 = 786,432 pixels × 24 bits/pixel = 18,874,368 bits = 2,359,296 bytes = 2.25 MB
The video adapter's digital-to-analog converter (commonly called RAMDAC) converts computer-generated digital images into analog signals that a monitor can display. The speed of a digital-to-analog converter is measured in MHz; The faster the conversion process, the higher the vertical regeneration frequency. In modern high-performance video adapters, performance can reach 300 MHz and higher.
As the speed of the digital-to-analog converter increases, the vertical refresh rate increases, which allows you to achieve more high resolution screen at optimal refresh rates (72–85 Hz or more). As a rule, video adapters with speeds of 300 MHz and higher support resolutions up to 1,920x1,200 at refresh rates of more than 75 Hz. Of course, do not forget to make sure that the required resolution is supported by both the monitor and the video adapter you are using.
Connector Video adapters are usually connected to the AGP connector on the motherboard; graphics adapters for PCI are less common - this is rather the province of older models of video adapters.
The video adapter communicates with the monitor via a special VGA or DVI interface (Figure 18).
Figure 16 – DVI and VGA connectors
VGA is an analog signal transmission interface, i.e. Control signals for three primary colors are transmitted, but each signal has 64 brightness levels. As a result, the number of possible combinations (colors) increases to 262,144 (64 
). To create a realistic image using computer graphics color is often more important than high resolution, since the human eye perceives a picture with more color shades as more believable.
DVI is a digital signal transmission mode, i.e. the signal is converted to analog not when leaving the video adapter, but in the monitor itself. This is the advantage of DVI over VGA. A digital signal has only two discrete values: 1 and 0, i.e. every time you transfer a unit digitally, you receive exactly one unit. Regardless of voltage fluctuations or any interference occurring during transmission. In an analog system, as a result of transmitting a unit, you can no longer get a unit, but 0.935 or 1.062. Therefore, it is not necessary that you see on the screen exactly what the video card generates.
The main characteristics of the video adapter are: memory frequency, processor frequency, type of slot and connector for connecting to the monitor.
