High-resolution graphics card (5)

EE January 1986 by P Lavigne a- D Meyer The graphics control program, further on referred to as "video inter- preter", consists of a little less than 4Kbytes of 6502 machine code located in host computer memory. To understand the use of the available video commands, it is useful to have datacards 116, 117 and 118 to hand for reference. The colour extension as promised in the preceding article in this series will be featured in next month"s issue. For now, the present video interpreter already supports all commands for use with the colour extension, so no software patching is required once this extension is put together. Video and/or graphics terminal The video interpreter allows the graphics card to function either as text or graphics terminal, or both at the same time. In the case of text mode, the screen is organized as 32 lines and 80 columns, whereas the graphics mode divides the screen in 512 x 256 or 512 x 512 pixels with 16 selectable colours. In the case of a text/graphics...