=== CGA ===
Enabled On RGBI monitors, it enabled mostly 320x200 display with a palette of 4 colours choosen between 4 combinations (only one colour to be chosen) from 16 total colours. Could It also get offered a text mode with character attribute based 16 colours display. On composite monitors or TVs, composite output enabled artifact-based NTSC colour emulation, simulating more colours (typically 16 colours simultaneously, but up to 1024 colours have been demonstrated).
The Amstrad CPC can quite be considered a custom and more versatile CGA.
The widely used VGA mode was the MCGA : 320x200x256. When those kind of display were widely available the CGA and EGA were obsolete and the PC could start to kick Amiga and Atari ST standards out of the place. VGA could also display a 640x480x16 video mode. All those from a 262,144colour total palette (6x6x6 bits).
VGA could emulate all CGA and EGA modes. However, as VGA monitors no longer supported 15.7kHz signalsscan rates, CGA, EGA, and MCGA modes were line-doubled to match the monitor's capabilities.
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