The MOS 6567/6569 video controller (VIC-II) and its application in the Commodore 64
Contents 3. Description of the VIC 3.7. Text/bitmap display 3.7.3. Graphics modes
3.7.3.7. Invalid bitmap mode 1 (ECM/BMM/MCM=1/1/0) |
This mode also only displays a black screen, but the pixels can also be read out with the sprite collision trick. The structure of the graphics is basically as in standard bitmap mode, but the bits 9 and 10 of the g-addresses are always zero due to the set ECM bit and so the graphics is - roughly said - made up of four "sections" that are each repeated four times. c-access
Adresses
13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
VM13 | VM12 | VM11 | VM10 | VC9 | VC8 | VC7 | VC6 | VC5 | VC4 | VC3 | VC2 | VC1 | VC0
Data
11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
unused
g-access
Adresses
13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
CB13 | VC9 | VC8 | 0 | 0 | VC5 | VC4 | VC3 | VC2 | VC1 | VC0 | RC2 | RC1 | RC0
Data
7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
8 pixels (1 bit/pixel) "0": Black (background) "1": Black (foreground)