Editing TRS-80 Color Computer (section)

====Artifact colors====
[[Image:6847 NTSC-färg.png|thumb|320px|Orange artifact color generated with the white and black colorset]]

The 256×192 two color graphics mode can display four colors due to a quirk in the NTSC television system. It is similar to the Apple II's DHGR graphics but slightly lower resolution and with four rather than six colors. These are called [[composite artifact colors]]. Two 6k pages can be used and the location of them differs depending on whether the disk controller is in use or not. If it is plugged into the expansion port, the graphics page begins at $E00 and at $600 if not (cassette software that utilizes the hi res mode would require the disk controller to be removed to ensure the graphics page is where the software expects it to be in).

In the first color set, where green and black dots are available, alternating columns of green and black appear as a muddy green color. With the white and black color set, the result is either orange or blue. Reversing the order of the alternating dots gives the opposite color. In effect, this mode is 128×192 with four colors: black, orange, blue, and white. On [[PAL]] televisions, instead of solid orange and blue, artifacts appear as vertical stripes of green and peach with soft edges and a width of almost four pixels. On a CoCo 3 with an analog RGB monitor, the black and white dot patterns do not artifact.

The bit patterns that represent orange and blue can be different each time the system is powered up. Most Color Computer games start with a title screen and ask the user to press the reset button until the colors are correct. This is fixed on the Color Computer 3 and the other color set can be chosen by holding {{Key press|F1}} during reset.