🚀 go-pugleaf

In article <tmorris.726292471@bruny>,
 tmorris@bruny.cc.utas.edu.au (Tim Morris) writes:
>
> Is it possible to select different colours using standard VT-100 codes?
> How do monochrome terminals react to these codes?

Well, the VT100 has a black-and-white screen, so don't expect much in
the way of pastel hues.  Some of its descendents, such as the VT241,
can display colors, but require use of the ReGIS graphics protocol to
change them.

The ANSI X3.64 standard itself does not contain any definitions for
changing color, but the corresponding international standard, ISO
DP6429, defines a way to specify colors using the SGR (Set Graphics
Rendition) command.

These 6429-style color functions are in fairly wide use.   Two pieces
of software that employ them are Microsoft's ANSI.SYS driver for MS-DOS
and Joe Doupnik's MS-Kermit program.  They take the form:

    ESC [ Fg ; Bg m

where Fg controls the foreground color and Bg controls the background.
These are expressed as ASCII decimal digits, not binary quantities.
Construct the Fg parameter by taking 30 and adding values for the primary
colors to it; construct Bg by adding primaries to 40.  (The "m" is a
literal lowercase M.)

   1 = red
   2 = green
   4 = blue

You can put other attributes in the string, too.

So, cyan (green + blue) foreground on black background would be

    ESC [ 36 ; 40 m

(no actual spaces appear in the control string, of course)

Among other places, this is documented in part of MS-Kermit documentation
in the file MSVIBM.VT, which you can obtain from WATSUN.CC.COLUMBIA.EDU.

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