Re: Adequacy of min-colors thresholds

On Tuesday, July 14th, 2026 at 9:25 AM, Stephen Berman <stephen.berman@gmx.=
net> wrote:

> On Mon, 13 Jul 2026 19:42:52 +0000 Heime <[email protected]> wro=
te:
>=20
> > On Tuesday, July 14th, 2026 at 6:25 AM, Eli Zaretskii <[email protected]> wr=
ote:
> >
> >> > Date: Mon, 13 Jul 2026 17:44:17 +0000
> >> > From: Heime <[email protected]>
> [...]
> >> > And what is a (min-colors 88) exactly?
> >>
> >> Any terminal that supports at least 88 colors.
> >
> > Why the chosen 88?  Is that some special terminal support?
>=20
> See https://www.invisible-island.net/xterm/xterm.faq.html#color_by_number=
:
>=20
>   In development of xterm over the past 20 years, we

Is the xterm color support due to the capability of running Emacs in termin=
al mode?
=20
>   * incorporated ANSI (8) colors,
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>   * adapted the aixterm feature (16) colors,
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>   * added extensions for 88- and 256-colors.
>   [...]
>   The 256-color extension came first. 88-colors (using the same control
>   sequence) came next, to reduce the amount of memory needed. XTerm
>   stores both foreground and background color indexes for each cell on
>   the screen. That is two bytes, which doubled the amount of memory used
>   by xterm for the scrollback. More important, however, was the number
>   of entries in the colormap. With 256 colors, 65536 entries might be
>   used, but 88 colors use at most 7744 entries. In the late 1990s,
>   inexpensive displays were far less capable, requiring workarounds to
>   get acceptable performance.
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> Steve Berman
>=20
>