tofro wrote:Speed reduction:
Note that, even if the contention created by video circuitry eats a lot of memory bandwidth, the 256 and 64k colour modes are way easier (and faster) to handle than the original QL modes:
Setting a pixel in mode 4 or 8 means
- pick the word containing the pixel from video memory
- Create (or reference) a proper mask that addresses the proper pixel in that word
- Clear the pixel to black
- OR in a properly shifted color mask
- write the screen word back to video memory
In modes 16 and 33 you simply move the pixel color to the proper place in video memory as a .B or .S. Done.
So speed is always relative - from a programming viewpoint, the 256 and 65535 color modes are way faster than the original modes 4 and 8. Probably even if you take into account that you need to modify a lot more pixels at higher resolutions.
Considering you might want to plot sprites, there is a way to do that extremely fast, without masks, and most of the time with no loading of the 'background' to insert your sprite shape in it.
The reason I want a Q68 is to adapt what I have completed writing for the Archie ('chunky' or linear mode, like for the Q68 screen modes with same layout).
You can watch here if interested :
https://www.youtube.com/results?search_ ... freload=10
Btw : again all this shouldn't be in this thread.
Maybe creating a specific thread 'plotting data on screen with Q68' would make everything more readable and interesting ?