MC6847

The MC6847 is a video display generator (VDG) first introduced by Motorola and used in the Dragon 32, Dragon 64, Dragon 200 and Dragon Alpha. It is a relatively simple display generator compared to other display chips of the time. It is capable of displaying text and graphics contained within a roughly square display matrix 256 pixels wide by 192 lines high. It is capable of displaying 9 colors: black, green, yellow, blue, red, buff (almost-but-not-quite white), cyan, magenta, and orange. The low display resolution is a necessity of using television sets as display monitors. Making the display wider risked cutting off characters due to overscan. Compressing more dots into the display window would easily exceed the resolution of the television and be useless.

Video Modes

Video Mode	Resolution	Colours	Bytes
Alphanumeric Internal	32 x 16	1 + Black	512
Alphanumeric External	32 x 16	1 + Black	512
Semigraphics 4	64 x 32	8 + Black	512
Semigraphics 6	64 x 48	4 + Black	512
Color Graphics 1	64 x 64	4	1024
Resolution Graphics 1	128 x 64	1 + Black	1024
Color Graphics 2	128 x 64	4	2048
Resolution Graphics 2	128 x 96	1 + Black	1536
Color Graphics 3	128 x 96	4	3072
Resolution Graphics 3	128 x 192	1 + Black	3072
Color Graphics 6	128 x 192	4	6144
Resolution Graphics 6	256 x 192	1 + Black	6144