@OG - Thumbing through the source code..
The fast blit mode behavior is documented here on 4-41 of the Software Developers Guide:
Fast BLT mode--provided to
enhance master-slave double
buffering. In fast BLT mode,
the system moves data from the
source to the destination as
quickly as possible by:
1. Ignoring the current setting of the transfer mode
(opaque or replace mode is
2. Ignoring the current setting of collision detect
(collision testing is
Clipping, if enabled, is performed as usual. The user must
ensure that, after clipping:
1. (DX) bits 0 through 3 are
2. The first pixel of both the
source and destination rectangles are word aligned.
3. The width of the transferred rectangle is an
integer number of words.
I suspect they added this specifically for cases where the programmer wanted to implement their own double buffering via the set destination buffer command, to make things faster.
Also, is the font/blt string trap taken care of by the existing blitter code? I'm having trouble getting blt string output to display at all.
Last edited by TSCHAK; 07/31/19 04:43 PM.