|
The Color Graphics Adapter (CGA), originally also called the ''Color/Graphics Adapter'' or ''IBM Color/Graphics Monitor Adapter'',〔(); cf. section 1-133, "Color/Graphics Adapter", page 143 of ibm_techref_v202_1.pdf〕 introduced in 1981, was IBM's first graphics card and first color display card for the IBM PC. For this reason, it also became that computer's first color computer display standard. The standard IBM CGA graphics card was equipped with 16 kilobytes of video memory and could be connected either to a dedicated direct-drive CRT monitor using a 4-bit digital (TTL) "RGBI"〔Red, Green, Blue, Intensity〕 interface, such as the IBM 5153 color display, or to an NTSC-compatible television or composite video monitor via an RCA connector. The RCA connector provided only baseband video, so to connect the CGA card to a standard television set required a separate RF modulator.〔(There was also a connector on the original IBM CGA cards for an add-on RF modulator unit installed inside the computer case, but no such device was offered by IBM, and it would have had to provide its own output connector separate from the ones on the CGA itself.)〕 Built around the Motorola MC6845 display controller, the CGA card featured several graphics and text modes. The highest display resolution of any mode was 640×200, and the highest color depth supported was 4-bit (16 colors). ==Output capabilities== CGA supports: * 320×200 in 4 colors from a 16 color hardware palette. Pixel aspect ratio of 1:1.2. * 640×200 in 2 colors. Pixel aspect ratio of 1:2.4 (The pixel ratio stems from rendering said amount of pixels on a 4:3 screen, a monitor ratio typical of that time.) Text modes: * 40×25 with 8×8 pixel font (effective resolution of 320×200) * 80×25 with 8×8 pixel font (effective resolution of 640×200) Extended graphics modes: * 160×100 16 color mode * Artifact colors using a NTSC monitor (16 colors from more than 100 possible) Cga p0.png|CGA 320x200 in 4 colors palette 0 Cga p1.png|CGA 320x200 in 4 colors palette 1 Cga p3.png|CGA 320x200 in 4 colors 3rd palette Cga 640x200.png|CGA 640×200 in 2 colors Cga 150x100.png|CGA 160×100 16 color mode CGA Partial Mandelbrot Set.png|A partial Mandelbrot set rendered in CGA palette 1 Arachne CGA Mode.svg|Screenshot of Arachne displaying its embedded frames and tables test pages in CGA 640x200 mode Paku-paku5-dos.png|PakuPaku in 160×100 16 color mode CGA_program_interface.png|PCPaint in 320x200 3rd palette low intensity, showing a typical low resolution interface. Note the use of dithering to overcome the CGA palette limitations. CGA 640x200 game.png|Sim City in 640x200 monochrome. Note the use of dithering to simulate gray tones and non-square pixel ratio that deforms the fonts. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「color graphics adapter」の詳細全文を読む スポンサード リンク
|