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36-431: The VDC is the main component of the video signal generator logic, responsible for generating the timing of video signals such as the horizontal and vertical synchronization signals and the blanking interval signal. Sometimes other supporting chips were necessary to build a complete system, such as RAM to hold pixel data , ROM to hold character fonts , or some discrete logic such as shift registers . Most often

72-412: A SoG input. Sync on red and sync on blue are even rarer than sync on green, and are typically used only in certain specialized equipment. Sync on composite, not to be confused with composite sync, is commonly used on devices that output both composite video and RGB over SCART. The RGB signal is used for color information, while the composite video signal is only used to extract the sync information. This

108-477: A VDP chip, but built the whole video display controller from a lot of discrete logic chips, (examples are the Apple II , PET , and TRS-80 ). Because these methods are very flexible, video display generators could be very capable (or extremely primitive, depending on the quality of the design), but also needed a lot of components. Many early systems used some form of an early programmable logic array to create

144-433: A VGA-signal, which is created by GPU is being transported over a VGA-cable to the display controller. Both ends of the cable end in a VGA connector . Laptops and other mobile computers use different interfaces between the display controller and the display. A display controller usually supports multiple computer display standards . KMS driver is an example of a device driver for display controllers and AMD Eyefinity

180-430: A composite signal, such as NTSC , PAL or SECAM , the luminance , Brightness (Y) signal and the chrominance , Color (C) signals are encoded together into one signal. When the color components are kept as separate signals, the video is called component analog video (CAV), which requires three separate signals: the luminance signal (Y) and the color difference signals (R-Y and B-Y). Since component video does not undergo

216-401: A video signal on a display device (for example, a cathode-ray tube ; CRT) is a straightforward process complicated by the multitude of signal sources. DVD , VHS , computers and video game consoles all store, process and transmit video signals using different methods, and often each will provide more than one signal option. One way of maintaining signal clarity is by separating the components of

252-534: A video signal so that they do not interfere with each other. A signal separated in this way is called "component video". S-Video , RGB and YP B P R signals comprise two or more separate signals, and thus are all component-video signals. For most consumer-level video applications, the common three-cable system using BNC or RCA connectors analog component video was used. Typical formats are 480i (480 lines visible, 525 full for NTSC) and 576i (576 lines visible, 625 full for PAL). For personal computer displays

288-1009: A video source to a video display where both support 4:3 and 16:9 display formats, the PAL television standard provides for signaling pulses that will automatically switch the display from one format to the other. Component video requires an extra synchronization signal to be sent along with the video. Component video sync signals can be sent in several different ways: Digital component video makes use of single cables with signal lines/connector pins dedicated to digital signals, transmitting digital color space values allowing higher resolutions up to 1080p . RGB component video has largely been replaced by modern digital formats, such as DisplayPort or Digital Visual Interface (DVI) digital connections, while home theater systems increasingly favor High-Definition Multimedia Interface (HDMI), which support higher resolutions, higher dynamic range, and can be made to support digital rights management . The demise of analog

324-565: A video system; examples include the ZX Spectrum and ZX81 systems and Elektronika BK-0010 , but there were many others. Early implementations were often very primitive, but later implementations sometimes resulted in fairly advanced video systems, like the one in the SAM Coupé . On the lower end, as in the ZX81, the hardware would only perform electrical functions and the timing and level of

360-579: Is a macrocell , which contains logic implementing disjunctive normal form expressions and more specialized logic operations. Some of the CPLD features are in common with PALs : Other features are in common with FPGAs : The most noticeable difference between a large CPLD and a small FPGA is the presence of on-chip non-volatile memory in the CPLD, which allows CPLDs to be used for " boot loader " functions, before handing over control to other devices not having their own permanent program storage. A good example

396-500: Is a special brand of display controller with multi-monitor support. RandR (resize and rotate) is a method to configure screen resolution and refresh rate on each individual outputs separately and at the same time configure the settings of the windowing system accordingly. An example for this dichotomy is offered by ARM Holdings : they offer SIP core for 3D rendering acceleration and for display controller independently. The former has marketing names such as Mali-200 or Mali-T880 while

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432-436: Is generally an inferior sync method, as this often causes checkerboards to appear on an image, but the image quality is still much sharper than standalone composite video. Sync on luma is much similar to sync on composite, but uses the Y signal from S-Video instead of a composite video signal. This is sometimes used on SCART, since both composite video and S-Video luma ride along the same pins. This generally does not suffer from

468-431: Is implemented as integrated circuits , often licensable as semiconductor intellectual property core (SIP core). Display controller System In Package (SiP) blocks can be found on the die of GPUs , APUs and SoCs . They support a variety of interfaces : VGA , DVI , HDMI , DisplayPort , VHDCI , DMS-59 and more. The PHY includes LVDS , TMDS and Flat Panel Display Link , OpenLDI and CML . For example,

504-436: Is largely due to screens moving to large flat digital panels as well as the desire for having a single cable for both audio and video, but also due to a slight loss of clarity when converting from a digital media source to analog and back again for a flat digital display, particularly when used at higher resolutions where analog signals are highly susceptible to noise. Examples of international component video standards are: In

540-456: Is less common, and while some VGA monitors support it, most do not. Sony is a big proponent of SoG, and most of their monitors (and their PlayStation line of video game consoles) use it. Like devices that use composite video or S-video, SoG devices require additional circuitry to remove the sync signal from the green line. A monitor that is not equipped to handle SoG will display an image with an extreme green tint, if any image at all, when given

576-483: Is not completely clear when a "video chip" is a "video display controller" and when it is a "video display processor". For example, the TMS9918 is sometimes called a "video display controller" and sometimes a "video display processor". In general however a "video display processor" has some power to "process" the contents of the video RAM (filling an area of RAM for example), while a "video display controller" only controls

612-454: Is where a CPLD is used to load configuration data for an FPGA from non-volatile memory. CPLDs were an evolutionary step from even smaller devices that preceded them: PLAs (first shipped by Signetics ) and PALs . These in turn were preceded by standard logic products, which offered no programmability and were used to build logic functions by physically wiring several standard logic chips (or hundreds of them) together (usually with wiring on

648-474: The Motorola 6845 ) as a basis and expand its capabilities with programmable logic or an ASIC . An example of such a hybrid solution is the original VGA card, that used a 6845 in combination with an ASIC. That is why all current VGA based video systems still use the hardware registers that were provided by the 6845. With the advancements made in semiconductor device fabrication , more and more functionality

684-546: The PCI Express bus, as they require much greater bandwidth then the ISA bus can deliver. Component video sync Component video is an analog video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video (CAV) information that is transmitted or stored as three separate signals. Component video can be contrasted with composite video in which all

720-641: The S-Video component video output (two separate signals) and the YP B P R component video output (three separate signals) seen on DVD players are examples of this method. Converting video into luma and chroma allows for chroma subsampling , a method used by JPEG and MPEG compression schemes to reduce the storage requirements for images and video (respectively). Many consumer TVs, DVD players, monitors, video projectors and other video devices at one time used YP B P R output or input. When used for connecting

756-476: The 15 pin DIN connector (IBM VGA) provided screen resolutions including 640×480, 800×600, 1024×768, 1152×864, 1280×1024. The various RGB (red, green, blue) analog component video standards (e.g., RGBS, RGBHV, RGsB) use no compression and impose no real limit on color depth or resolution, but require large bandwidth to carry the signal and contain a lot of redundant data since each channel typically includes much of

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792-553: The 1990s through the 2000s when they were largely replaced with HDMI and other all-digital standards. Component video cables and their RCA jack connectors on equipment are normally color-coded red, green and blue, although the signal is not in RGB . YPbPr component video can be losslessly converted to the RGB signal that internally drives the monitor; the encoding is useful as the Y signal will also work on black and white monitors. Reproducing

828-514: The VDC chip is completely integrated in the logic of the main computer system, (its video RAM appears in the memory map of the main CPU), but sometimes it functions as a coprocessor that can manipulate the video RAM contents independently. The difference between a display controller, a graphics accelerator, and a video compression/decompression IC is huge, but, since all of this logic is usually found on

864-424: The capabilities of early PLA-based systems were often less impressive than those using the video interface controllers or video coprocessors that were available at the same time. Later PLA solutions, such as those using CPLDs or FPGAs , could result in much more advanced video systems, surpassing those built using off-the-shelf components. An often-used hybrid solution was to use a video interface controller (often

900-672: The chip of a graphics processing unit and is usually not available separately to the end-customer, there is often much confusion about these very different functional blocks. GPUs with hardware acceleration became popular during the 1990s, including the S3 ViRGE , the Matrox Mystique , and the Voodoo Graphics ; though earlier examples such as the NEC μPD7220 had already existed for some time. VDCs often had special hardware for

936-519: The chips used on these ISA / EISA cards consisted solely of a display controller, as this was the only functionality required to connect a computer to a display. Later cards included ICs to perform calculations related to 2D rendering in parallel with the CPU; these cards were referred to as graphics accelerator cards. Similarly, ICs for 3D rendering eventually followed. Such cards were available with VLB , PCI , and AGP interfaces; modern cards typically use

972-532: The creation of " sprites ", a function that in more modern VDP chips is done with the " Bit Blitter " using the " Bit blit " function. One example of a typical video display processor is the " VDP2 32-bit background and scroll plane video display processor " of the Sega Saturn . Another example is the Lisa (AGA) chip that was used for the improved graphics of the later generation Amiga computers. That said, it

1008-426: The encoding process, the color quality is noticeably better than composite video. Component video connectors are not unique in that the same connectors are used for several different standards; hence, making a component video connection often does not lead to a satisfactory video signal being transferred. Many DVD players and TVs may need to be set to indicate the type of input/output being used, and if set incorrectly

1044-402: The image may not be properly displayed. Progressive scan , for example, is often not enabled by default, even when component video output is selected. Complex programmable logic device A complex programmable logic device ( CPLD ) is a programmable logic device with complexity between that of PALs and FPGAs , and architectural features of both. The main building block of the CPLD

1080-521: The latter is available as Mali-DP500, Mali-DP550 and Mali-DP650. In 1982, NEC released the NEC μPD7220 , one of the most widely used video display controllers in 1980s personal computers . It was used in the NEC PC-9801 , APC III , IBM PC compatibles , DEC Rainbow , Tulip System-1 , and Epson QX-10 . Intel licensed the design and called it the 82720 graphics display controller. Previously, graphic cards were also called graphic adapters, and

1116-797: The same black-and-white image. Early personal computers such as the IBM PS/2 offered this signal via a VGA port . Many televisions, especially in Europe, can utilize RGB via the SCART connector. In addition to the red, green and blue color signals, RGB requires two additional signals to synchronize the video display. Several methods are used: Composite sync is common in the European SCART connection scheme (using pins 17 [ground] and 19 [composite-out] or 20 [composite-in]). RGBS requires four wires – red, green, blue and sync. If separate cables are used,

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1152-589: The same checkerboard issue as sync on composite, and is generally acceptable on devices that do not feature composite sync, such as the Sony PlayStation and some modded Nintendo 64 models. Further types of component analog video signals do not use separate red, green and blue components but rather a colorless component, termed luma , which provides brightness information (as in black-and-white video). This combines with one or more color-carrying components, termed chroma , that give only color information. Both

1188-497: The sync cable is usually colored yellow (as is the standard for composite video) or white. Separate sync is most common with VGA , used worldwide for analog computer monitors . This is sometimes known as RGBHV, as the horizontal and vertical synchronization pulses are sent in separate channels. This mode requires five conductors. If separate cables are used, the sync lines are usually yellow (H) and white (V), yellow (H) and black (V), or gray (H) and black (V). Sync on Green (SoG)

1224-619: The timing of the video synchronization signals and the access to the video RAM. The graphics processing unit (GPU) goes one step further than the VDP and normally also supports 3D functionality. This is the kind of chip that is used in modern personal computers. Video display controllers can be divided in several different types, listed here from simplest to most complex; Examples of video display controllers are: Video shifters CRT Controllers Video interface controllers Video coprocessors Note that many early home computers did not use

1260-415: The video information is combined into a single signal that is used in analog television . Like composite, component cables do not carry audio and are often paired with audio cables . When used without any other qualifications, the term component video usually refers to analog YP B P R component video with sync on luma (Y) found on analog high-definition televisions and associated equipment from

1296-459: The video stream was provided by the microprocessor. As the video data rate was high relative to the processor speed, the computer could only perform actual non-display computations during the retrace period between display frames. This limited performance to at most 25% of overall available CPU cycles. These systems could thus build a very capable system with relatively few components, but the low transistor count of early programmable logic meant that

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