DECALN Screen Alignment Test
Fill the screen with the letter E.
ESC # 8
- DEC STD 070
- §D.8 Screen Alignment, p. D-19
- VT220
- §4.19.2 Adjustments (DECALN)
- VT510
- DECALN—Screen Alignment Pattern
Fill every cell of the screen with an E. It was meant for adjusting the focus and linearity of a CRT, and it lives on because it is the quickest way to put something in every cell: many of the cases on this site start with it before erasing or scrolling part of the screen.
Along the way it resets the top and bottom margins, and the left and right ones, to the whole screen, and moves the cursor to the top-left.
Support
| Terminal | Version | Support | Notes |
|---|---|---|---|
| VT220 | manual, 2nd ed., 1984 | Yes | §4.19.2 Adjustments (DECALN) |
| VT510 | manual, 1st ed., 1993 | Yes | DECALN |
| xterm | patch 412, xterm-411a | Yes | |
| libghostty-vt | 0f171f6 | Yes | |
| kitty | 0.49.1, run in a VM | Yes | passes the 2 cases that show it working |
| foot | 1.28.0, run in a VM | Yes | passes the 2 cases that show it working |
| pyte | 0.8.2, run as a library | No | fails the 2 cases that show it working |
| xterm.js headless | 6.0.0, run as a library | Partly | fails DECALN-2 of the 2 cases that show it working |
| alacritty_terminal | 0.26.0, run as a library | No | fails the 2 cases that show it working |
| ConEmu | build 230724, its documentation | No | not in ConEmu’s ANSI escape codes |
| rxvt-unicode | 9.31, run in a VM | No | fails the 2 cases that show it working |
| VTE | 0.84.1, run as a library | Yes | passes the 2 cases that show it working |
Validation
DECALN-1: Fills the screen
\e[2;3H
\e#8
|EEEE|
|EEEE|
|EEEE|
cursor 1,1
DECALN-2: Resets the scrolling region
\e[1;2r # region is lines 1 and 2
\e#8
\e[2;1H
\n # would scroll if the region were still set
|EEEE|
|EEEE|
|EEEE|
cursor 3,1