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
3.7.3.6. Invalid text mode (ECM/BMM/MCM=1/0/1) |
Setting the ECM and MCM bits simultaneously doesn't select one of the "official" graphics modes of the VIC but creates only black pixels. Nevertheless, the graphics data sequencer internally generates valid graphics data that can trigger sprite collisions even in this mode. By using sprite collisions, you can also read out the generated data (but you cannot see anything, the screen is black). You can, however, only distinguish foreground and background pixels as you cannot get color information from sprite collisions. The generated graphics is similar to that of the multicolor text mode, but the character set is limited to 64 characters as in ECM mode. 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
MC flag | unused | D5 | D4 | D3 | D2 | D1 | D0
g-access
Adresses
13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
CB13 | CB12 | CB11 | 0 | 0 | D5 | D4 | D3 | D2 | D1 | D0 | RC2 | RC1 | RC0
Data
7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
MC flag=0
8 pixels (1 bit/pixel) "0": Black (background) "1": Black (foreground)
MC flag=1
4 pixels (2 bits/pixel) "00": Black (background) "01": Black (background) "10": Black (foreground) "11": Black (foreground)