Legacy graphics

Two vector protocols predate every bitmap protocol. They are documented here because xterm still implements them and because their design explains why Sixel scrolls the way it does.

ReGIS

Status: DEC. Remote Graphics Instruction Set, VT125, VT240, VT330/VT340.

DCS Pn p command-string ST

Pn 0 or 1 resumes or starts a fresh command set. Commands are single letters with bracketed arguments: S screen control, W writing control, P position, V vector, C curve, T text, L load character set, F fill, R report. Example, a line from the origin to (100,100):

DCS p S(E) P[0,0] V[100,100] ST

ReGIS draws on a graphics plane the size of the screen, independent of text cells; scrolling text does not move it. xterm implements it only when built with --enable-regis-graphics and the terminal ID is 240 or above.

Tektronix 4014

Status: xterm.

CSI ? 38 h    switch to Tektronix mode (xterm opens a separate window)
ESC ^C        return to VT mode from Tektronix

xterm emulates a Tektronix 4014 storage-tube display in a separate window, driven by the 4014's own byte protocol (GS for vector mode, FS point plot, US alpha mode). It exists for legacy plotting software such as old gnuplot drivers and has no modern users.

Why not use these

• No modern emulator other than xterm implements ReGIS; none implements Tektronix.
• Vector protocols have no palette or raster model, so photographs are impossible.
• Modern terminals are UTF-8 and cell-oriented; a separate graphics plane does not survive scrollback, resizing, or multiplexing.

For new work use Sixel for breadth, the Kitty protocol for lifecycle control, or the iTerm2 protocol for macOS-centric tools.

Probe

printf '\033Pp S(E) P[0,0] V[200,100] \033\\'    # ReGIS line, xterm -ti vt340
printf '\033[?38h'                               # xterm: opens the Tek window

Sources

• VT330/VT340 Programmer Reference, ReGIS chapters
• XTerm Control Sequences
• Xterm Tektronix emulation, xterm manual

Compatibility

Feature support by terminal. Imported claims have not been reverified; unknown is not unsupported.

Feature / stable ID	Alacritty	Apple Terminal	ConPTY (conhost)	Contour	DomTerm	foot	Ghostty	iTerm2	kitty	Konsole	mintty	mlterm	PuTTY	Revenant	RLogin	st	tmux	rxvt-unicode	VTE	wayst	WezTerm	Windows Terminal	xterm	xterm.js
ReGIS dcs-regis	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	SupportedImported · unverified	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	SupportedImported · unverified	Unknown
Tektronix tek-4014-graphics	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	SupportedImported · unverified	Unknown