Show pageOld revisionsBacklinksBack to top This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong. ====== Sinclair QL - Displaying Bitmaps & Text ====== Direct video memory Video memory starts at 0x20000 In Mode 4 (512x256 4 colour) the memory is laid out in byte pairs (or words) <code> Red byte | Green byte 0 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0 </code> Those 16 bits set a series of **8** contiguous horizontal pixels. The values of the //Red// and //Green// byte are AND-ed to get the final colour: <code> Red | Green | Result 1 | 0 | Red 0 | 1 | Green 1 | 1 | White 0 | 0 | Black </code> Example 1: <code> 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 </code> ...would draw an 8 pixel horizontal line in //Green//. Example 2: <code> 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 </code> ...would draw an 8 pixel horizontal line in //White//. Example 3: <code> 1 0 1 0 1 0 1 0 0 1 0 1 0 1 0 1 </code> ...would draw 8 alternating pixels of //Red// and //Green//. blog/ql_dev2.txt Last modified: 2021/12/14 21:09by john