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DECSSCLS — set scroll speed

Category: modes · Baseline: legacy · Tags: VT510 · Specification ↗

DECSSCLS (Set Scroll Speed) controls how fast the terminal scrolls when new lines are added at the bottom. The sequence is CSI Ps p where Ps specifies the scroll speed: 0 or 1 for normal speed, 2-8 for progressively faster speeds. Defined in the VT510 reference manual. This is a VT510-era feature that controlled the physical scrolling speed of CRT terminals. On modern terminal emulators it has little practical effect since rendering is immediate, but Contour implements it for VT510 compatibility.
How this is testedpartial
Send DECSSCLS sequence and verify it's accepted without error.

The same probe runs against headless backends (via Termless) and real terminal apps (via a daemon launched in each terminal). This lets us distinguish parser correctness from rendering correctness.

Supported by 0 of 14 backends (0%)

Terminal Applications

TerminalVersionSupportNotes
iTerm23.6.9? unknown
Ghostty1.3.1? unknown
VS Code? unknown
Kitty0.46.2? unknown
Warp? unknown
Cursor? unknown
Terminal.app? unknown

Headless Backends

Parser correctness only — a means the parser accepts the sequence.

BackendVersionSupportNotes
Alacritty0.26.0? unknown
vt100.js0.2.1? unknown
vterm0.2.0? unknown
WezTerm0.1.0-fork.5? unknown
xterm.js5.5.0? unknown