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close this bookNew Training Technologies (ILO - UNEVOC, 1995, 95 p.)
close this folderAppendix A Compatibility
View the document(introduction...)
View the documentPC buses (architecture)
View the documentMicroprocessors
View the documentOperating systems
View the documentGraphic modes
View the documentDigital images, sound and video files
View the documentColour standards
View the documentVideotape formats

Graphic modes

The graphics adapter that equips a PC determines the quality of text and images one can show on the display screen:

· the CGA (Colour Graphics Adapter) adapter is cheap and offers a rather poor quality; 320x200 pixels and four colours, or 640x200 pixels in black and white; WINDOWS does not support this type of graphics adapter;

· the MCGA (Multi Colour Graphics Adapter) adapter is offered by IBM with 320x200 pixels and 256 colours out of 256,000; or 640x480 pixels and two colours (black and white);

· the EGA (Enhanced Graphics Adapter) adapter offers 640x350 pixels with 16 colours out of 64;

· the VGA (Video Graphics Array) adapter is offered by IBM with 640x480 pixels with 16 colours out of 256,000 (262,144), or 64 grey shades on a mono display;

· the VGA8 adapter is offered by IBM with 360x480 pixels and 256 colours out of 256,000; it works on VGA display screens;

· the 8514/A adapter if offered by IBM with 640x480 and 256 colours, or 1024x768 and 256 colours when the application supports it;

· the XGA (Extended Graphics Adapter) adapter is offered by IBM with 1024x768 pixels and 256 colours out of 256,000;

· the SVGA (Super VGA) adapter is offered by all other manufacturers and works with 1024x768 pixels, with 256 colours.

Quality images recorded with a certain resolution can be converted by certain software into a lower resolution; the reverse is unfortunately not possible. Compatibility always exists downwards: a SVGA screen may show a VGA image, but the reverse is not possible.