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From: bobmon@iuvax.cs.indiana.edu (RAMontante)
Newsgroups: comp.sys.ibm.pc.hardware,comp.os.msdos.misc
Subject: Re: CGA 16-color mode AND rare questions
Message-ID: <78524@iuvax.cs.indiana.edu>
Date: 17 Dec 90 15:34:53 GMT
References: <1990Dec17.005334.383@iowasp.physics.uiowa.edu>
Organization: 'twixt Dali and Dada
Lines: 19

The CGA "16-color low-resolution mode" is the text mode.  You get character
graphics.  The 16 colors are really eight colors, each available in two
intensities; but the bright intensity is only available for the foreground,
i.e. the characters.  If you try to put the background into high intensity
the display makes the foreground blink instead.  (Actually I think you can
reprogram the display adapter to provide high-intensity background, but it
doesn't seem all that valuable a thing to do.)

Low-resolution *graphics* mode gives you your choice of four four-color
palettes (actually, two palettes, each in high and low intensities).
One is red/yellow/green/black, the other is cyan/magenta/light-gray/black,
where black is the background color and can be changed to any one of 16
possibilities (but you will still have only four colors on the screen at
once).  You get 320x200 dots to color this way.

High-resolution graphics gives you 640x200 dots, but you only get black
and your-choice-of-one-of-16.

My Turbo C User's Guide has a helpful discussion of this.