deng@shire (Mingqi Deng) (02/22/89)
Can any netter tell me what differecnce VGA, EGA and CGA make and what 'campatible to VGA and EGA' implies? Thanks in advance. Mingqi deng@shire.cs.psu.edu deng@psuvaxs.uucp deng@psuvaxs.bitnet
marc@rna.UUCP (Marc Johnson) (02/24/89)
In article <4306@psuvax1.cs.psu.edu> deng@shire (Mingqi Deng) writes: >Can any netter tell me what differecnce VGA, EGA and CGA make and what >'campatible to VGA and EGA' implies? > >Thanks in advance. > >Mingqi CGA, EGA and VGA all stand for IBM's video interface standards, and each corresponds to an adapter card that IBM provided with various systems. The main difference between them is in resolution of the image and the number of colors available. CGA (Color Graphics Adapter) was first available with early PC systems, and provides 16 colors and 640 lines X 200 lines of resolution. Most graphics- and color-oriented software written until recent years was written for this standard. Its character rendition is generally considered to be poor for text-intensive applications. EGA (Enhanced Graphics Adapter) has gained popularity more recently, due to its superior character rendition in either 25- or 43-line modes, and greater graphics resolution (up to 640 X 350). EGA can also display 16 simultaneous colors, but these 16 are drawn from a palette of 64. EGA requires a monitor capable of handling the higher resolution is required for an EGA adapter card. EGA cards are generally fully CGA-compatible. Most business software and other recent software (including MicroSoft Windows) requires EGA. VGA is the latest and greatest. It was introduced by IBM with its PS/2 line. It supports up to 640 X 480 resolution, and 16 colors frmo a palette of 256,000 (!) colors. Actually, one VGA mode supports lower resolution (320 X 200) with 256 simultaneous colors. The popular MultiSync or MultiScanning monitors you may have seen around are able to handle higher-than-EGA resolutions, and in some cases, VGA. Because of the higher clock rates and bandwidth required for VGA, VGA-compatible monitors use analog display technology instead of the TTL (digital) technology used before. The MultiSync monitors have two input connectors and can handle the two different output modes, depending on the adapter card to which they're connected. It sounds like you're shopping either for a card or a monitor, so I suggest you take peek at BYTE February and March '88. -Marc =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= = Marc Johnson BITNET: rna!marc@rockvax.bitnet = = Rockefeller Univ. Neurobiology UUCP: ...cmcl2!rna!marc = = New York City INTERNET: marc%rna@rocky2.rockefeller.edu = = (129.85.2.1) = = = = "Gimme the beat boys and free my soul, I wanna get lost in your rock & roll = = ...and drift away" = =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
avenger@runx.ips.oz (Troy Rollo ) (02/26/89)
> > Can any netter tell me what differecnce VGA, EGA and CGA make and what > 'campatible to VGA and EGA' implies? > CGA = Colour graphics adapter. Likje a monochrome display adapter with 160x100 16 colour, 320x200 4 colour and 640x200 monochrome graphics. Colour registers exist on CGA and EGA with 6 bits for each colour which define the physical colour displayed for a given colour number. EGA = Enhanced graphics adapter Can emulate a CGA to an extent - some clone boards emulate CGA properly - as well as a 640x350 monochrome, 640x350 16 colour. Text is much easier to read on EGA than CGA VGA = Video Graphics Adapter Can emulate EGA and CGA - most can do so fully. Some also emulate MDA and Hercules. Ideally you should try to get one which has full register level downward compatibility with CGA and EGA. Text modes are enhances by adding an extra 50 scan lines (350->400), and there are 3 new graphics modes - 640x480 2 colour, 640x480 16 colour and 320x200 256colour. There are 64 ... oops 256 colour registers each with 24 bits, although only 18 bits are used, with 256000 possible colours and shades. Most modes can take advantage of this. Some cards have additinal modes including: 132x44 text, 132x25 and 132x28 all with 4 colours 1056x352, 1056x350, 1056x364 all 16 colours 640x40 800x600 256 colours 024x768 16 colours ---------------------------------------------------------------- Internet: avenger@runx.ips.oz.au ________________________ UUCP: uunet!runx.ips.oz.au!avenger /\ \ \_| | Watch out for gobbledocks - | Core Publications | They'll steal all your silicon Chippies | Electronic Publishing | | ____________________|_ \_/_____________________/