For a more detailed discussion of VGA, see What is VGA, and how does it work?
The 8514/a was the next graphics offering from IBM and provides three new video modes that are not available from the VGA controller. Computers with 8514/a hardware must also have a VGA controller, as the 8514/a does not support VGA video modes. The additional modes are: Type Pixel Max. # Colours Characters Addressability gfx 640×480 256 80×34 gfx 1024×768 256 85×38 (interlaced) gfx 1024×768 256 146×51 (interlaced) The 8514/a also has some smarts, as it is capable of performing video memory transfers, drawing lines and extracting rectangular areas of the display image. These are so-called accelerated features. The XGA has superseded the 8514/a. It was the first IBM display adapter to use VRAM, and can be configured with 500k or 1 Meg. Like the 8514/a, the XGA has accelerated features which make it faster than standard VGA for some operations. The new modes XGA introduced are: Mode Type Pixel Max. # Colours Characters Addressability 14 text 1056×400 16 132×25 – gfx 640×480 256/65535* –
