Английская Википедия:Extended Graphics Array
Шаблон:Redirect Шаблон:Distinguish Шаблон:Short description Шаблон:Use dmy dates Шаблон:Use british english Шаблон:Infobox GPU
The eXtended Graphics Array (usually called XGA) is a graphics card manufactured by IBM and introduced for the IBM PS/2 line of personal computers in 1990 as a successor to the 8514/A. It supports, among other modes, a display resolution of Шаблон:Resx pixels with 256 colors at 43.5 Hz (interlaced), or Шаблон:Resx at 60 Hz (non-interlaced) with up to 65,356 colors.[1][2] The XGA-2 added an Шаблон:Resx 65,356 color mode and Шаблон:Resx 60 Hz non-interlaced.[1]
The XGA was introduced at $1095 with 515K VRAM and additional $350 for the 512Шаблон:NbspKB memory expansion (equivalent to $Шаблон:Inflation and $Шаблон:Inflation, respectively, in Шаблон:Inflation/year).Шаблон:Inflation/fn[1] As with the 8514/A, XGA required a Micro Channel architecture bus at a time when ISA systems were standard, however due to more extensive documentation and licensing ISA clones of XGA were made. XGA was integrated into the motherboard of the PS/2 Model 95 XP 486.[2]
An improved version called XGA-2 was introduced in 1992 at $360, worth $Шаблон:Inflation in Шаблон:Inflation/year dollars.
Features
The 8514 had used a standardised API called the "Adapter Interface" or AI. This interface is also used by XGA, IBM Image Adapter/A, and clones of the 8514/A and XGA such as the ATI Technologies Mach 32 and IIT AGX. The interface allows computer software to offload common 2D-drawing operations (line-draw, color-fill, and block copies via a blitter) onto the hardware. This frees the host CPU for other tasks, and greatly improves the speed of redrawing a graphics visual (such as a pie-chart or CAD-illustration).[1][2] Hardware-level documentation of the XGA was also made, which had not been available for the 8514/A.[2]
XGA introduced a 64x64 hardware sprite which was typically used for the mouse pointer.
Differences from 8514/A
- Register-compatible with VGA[2]
- Adds a 132 column text mode and high color in Шаблон:Resx[2]
- Requires a minimum of 80386 host CPU[2]
- Provides a 3-dimensional drawing space called a "bitmap" which may reside anywhere in system memory[2]
- Adds a sprite for a hardware cursor[2]
- The Adapter Interface driver is moved to a .SYS file instead of TSR program[2]
- Provisions made for multitasking environment[2]
- XGA can act as bus master and access system memory directly[2]
- Hardware level documentation has been provided by IBM[2]
XGA-2
XGA-2 added support for non-interlaced Шаблон:Resx and made 1MB VRAM standard. It had a programmable PLL circuit and pixel clocks up to 90MHz, enabling a 75 Hz refresh rate at Шаблон:Resx. The Шаблон:Resx resolution was added with 16 bit high color support. The DAC was increased to 8 bits per channel, and the accelerated functions were enabled at 16 bit color depth. Faster VRAM also improved performance.[1]
Output capabilities
The XGA offered:
- Шаблон:Resx:
- graphics mode with 256 colors at once (8-bit) out of 262,144 (18-bit RGB palette);
- graphics with 65,536 colors at once (16-bit "high color");
- text mode with 80×34 characters
- Шаблон:Resx:
- graphics with 256 colors out of 262,144;
- text with 85×38 or 146×51 characters
XGA-2 introduced:
- Шаблон:Resx graphics with 256 colors out of 16.7M (24-bit palette);
- Шаблон:Resx graphics with 65,536 colors at once;
- Шаблон:Resx graphics with 256 colors out of 16.7M
Later clone boards offered additional resolutions:
- Шаблон:Resx graphics with 16.7M accessible colors at once (if it were possible with Шаблон:Resx pixels) (24-bit "true color");
- Шаблон:Resx graphics with 16.7M colors at once;
- Шаблон:Resx graphics with 65,536 and 16.7M colors at once
Clones
Шаблон:Commons Unlike with the 8514/A, IBM fully documented the hardware interface to XGA. Further, IBM licensed the XGA design to SGS-Thomson (inmos) and Intel. The IIT AGX014 was largely compatible with the XGA-2 and offered some enhancements.
The VESA Group introduced a common standardized way to access features like hardware cursors, Bit Block transfers (Bit Blt), off screen sprites, hardware panning, drawing and other functions with VBE/accelerator functions (VBE/AF) in August 1996. This, along with standardised device drivers for operating systems such as Microsoft Windows, eliminated the need for a hardware standard for graphics.
See also
References
Further reading
Шаблон:Computer display standard
- Английская Википедия
- Страницы с неработающими файловыми ссылками
- Computer display standards
- IBM video hardware
- Graphics cards
- Computer-related introductions in 1990
- Computer-related introductions in 1992
- IBM PS/2
- Страницы, где используется шаблон "Навигационная таблица/Телепорт"
- Страницы с телепортом
- Википедия
- Статья из Википедии
- Статья из Английской Википедии
