View Single Post
Old 27 August 2009, 13:55   #20
Thalion Webshrine
alexh's Avatar
Join Date: Jan 2004
Location: Oxford
Posts: 12,047
Originally Posted by Jgames View Post
now the question i would like an answer to is how the double buffering is done
I imagine either it isn't or they render to the back buffer and then copy to the screen buffer during a VSYNC period.

Originally Posted by Jgames View Post
If the amount of ram is much lesser than memory needed for a full screen display mode?
The CPC resolution is 160×200x4 ~= 16 Kbytes. So even two full screen locations + tile set + sprite set is much less than the system memory of 64 Kbytes.

Originally Posted by Jgames View Post
Maybe as i pointed before, most consoles don't do double buffering, and write directly to Vram?
Correct. They could use the VSYNC & HSYNC interrupts (or poll counters) to time accesses to RAM in such a way as to always be behind the electron gun. Not sure they did this, just I know it is possible.

Originally Posted by Jgames View Post
or write to a non displayable portion of Vram and flip (change address) to this vram when wanting to display
Not sure the early 8-bit consoles & home computers could "flip" the screen address? Pretty sure in most it was at a fixed location, no? If you needed to double buffer you have the overhead of copying too.

Last edited by alexh; 27 August 2009 at 14:09.
alexh is offline  
Page generated in 0.03898 seconds with 10 queries