[atari7800] Mode 160B don't works for me...

  • From: Manuel Rotschkar <cybergoth@xxxxxxxx>
  • To: atari7800@xxxxxxxxxxxxx
  • Date: Sun, 31 Oct 2004 13:40:38 +0100

Hi there!

Phew... I'm trying this for hours now, but I don't get to display anything in this mode. Meanwhile I tried so many things, actually by pure accident alone I should've managed to get at least some garbage displayed on the screen...

Ok, what did I do so far...

I wrote a program that strips of the header of a 16-color windows Bitmap, does the bitwise swapping of the 2-Bit pairs as described in the 7800 Guide.
(First I'm changing the nibbles 4,8&12 to 13-14, leaving 0 as transparent)

That results in a 16000 byte data block I simply include in my source file.

My Code does this:
- It writes %01000000 to the CRTL register
- It writes dummy values to all color registers.
- It sets the DLL pointer, then loops forever.

My DL entries look like this:

byte   $00,%11000000,$80,%10000001,0
byte   $20,%11000000,$80,%10000001,64
byte   $40,%11000000,$80,%10001001,128
byte   $00,$00

I attached the full source and my converted bitmap. My last hope is that one of you will see what I'm doing wrong here...


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