Date : Mon, 02 Mar 2009 13:28:03 +0000 (GMT)
From : tommowalker@... (Tom Walker)
Subject: Fwd: New Screen Modes with ARM7 Co-Processor?
> >Why does it need to be linearly addressable?
> Because the CRTC needs it to be. Why is that so hard to understand ?
No, the CRTC only needs to _think_ it is. Is this difficult to understand?
Vblank - load CRTC address for &3000, set &FE34 to display main bank
lines 0-127 (in our field) - CRTC displays main memory &3000-7FFF
line 128 - set &FE34 to display shadow bank, CRTC wraps back round to &3000
lines 128-255 - CRTC displays shadow memory &3000-7FFF
If you're so insistent that the CRTC needs to have the base address reloaded,
then fine! Set up a raster split for line 128, and reload it then.
I _have_ done this, making the CRTC display a 40k screen, so don't try and
tell me this is impossible.