On a real CoCo 3 and in MAME, bit 4 of the $FF98 video mode register will enable monochrome output on the composite and TV output. When bit 4 is set to 1, the composite (including TV) output of the Color Computer 3 is changed to black and white (monochrome). This allows easier reading and better resolution in higher resolution text and graphics modes. This bit will not affect the RGB display.
Setting bit 5 of the $FF98 register inverts the burst phase on composite and TV output. Technically, this bit tells the computer to invert the color burst phase going to the TV or composite monitor. Setting this bit will reverse the red and blue colors in the artifacting mode (i.e., PMODE 4). However, importantly, setting this bit affects all 64 colors, not just red and blue.
FF98 Video Mode Register
Bit 7 BP 0 = Text modes, 1 = Graphics modes
Bit 6 Unused
Bit 5 BPI Burst Phase Invert (Color Set)
Bit 4 MOCH 1 = Monochrome on Composite
Bit 3 H50 1 = 50 Hz power, 0 = 60 Hz power
Bits 0-2 LPR Lines per row
On a real CoCo 3 and in MAME, bit 4 of the $FF98 video mode register will enable monochrome output on the composite and TV output. When bit 4 is set to 1, the composite (including TV) output of the Color Computer 3 is changed to black and white (monochrome). This allows easier reading and better resolution in higher resolution text and graphics modes. This bit will not affect the RGB display.
Setting bit 5 of the $FF98 register inverts the burst phase on composite and TV output. Technically, this bit tells the computer to invert the color burst phase going to the TV or composite monitor. Setting this bit will reverse the red and blue colors in the artifacting mode (i.e., PMODE 4). However, importantly, setting this bit affects all 64 colors, not just red and blue.
FF98 Video Mode Register
Bit 7 BP 0 = Text modes, 1 = Graphics modes Bit 6 Unused Bit 5 BPI Burst Phase Invert (Color Set) Bit 4 MOCH 1 = Monochrome on Composite Bit 3 H50 1 = 50 Hz power, 0 = 60 Hz power Bits 0-2 LPR Lines per row