Terminal Models

Terminal Models

Select a model with --model. The default is VT420.

Model	Levels	Primary DA reply	Secondary DA	TERM
vt100	VT100	CSI ? 1;2 c	—	vt100
vt102	VT100	CSI ? 6 c	—	vt102
vt220	VT200, VT100, VT52	CSI ? 62;1;2;6;7;8;9 c	CSI > 1;10;0 c	vt220
vt320	VT300 and below	CSI ? 63;1;2;6;7;8;9 c	CSI > 24;10;0 c	vt320
vt420	VT400 and below	CSI ? 64;1;2;6;7;8;9;15;18;21 c	CSI > 41;10;0 c	vt420
vt510	VT500 and below	CSI ? 64;1;2;7;8;9;12;15;18;21;23;24;42 c	CSI > 61;10;0 c	vt520
vt520	VT500 and below	CSI ? 65;1;2;7;9;12;18;21;23;24;42 c	CSI > 64;10;0 c	vt520
vt525	VT500 and below, colour	CSI ? 65;1;2;7;9;12;18;21;22;23;24;42 c	CSI > 65;10;0 c	vt520

Hosts can lower the operating level with DECSCL (for example to VT100 mode) and switch to VT52 mode, as on the real terminals. In VT100 mode a VT220 or later answers DA as a VT102.

The VT510 reports class 64 in DA1, as its manual documents. Hosts can also choose the reported identity with DECTID (VT100 … VT520). The VT500 DA1 replies leave out extensions veetee does not provide yet: 19 sessions, 44 PCTerm, 45 soft key mapping and 46 ASCII emulation.

What each level adds

• VT100/VT102 — ANSI cursor control, scrolling regions, double-size lines, DEC Special Graphics, VT52 mode; the VT102 adds insert/delete line and character.
• VT220 — 8-bit controls, G0–G3 character sets with locking and single shifts, national replacement character sets, DEC Supplemental, soft fonts (DECDLD), user-defined keys, selective erase and protected fields.
• VT320 — ISO Latin-1, DEC Technical characters, the user-preferred supplemental set, status line, presentation state and mode reports.
• VT420 — left/right margins, rectangular area operations and checksums, page memory, 36- and 48-line screens, macros, terminal state reports.
• VT510/VT520 — CHA/HPA/VPA and the other ECMA-48 cursor functions, cursor styles (DECSCUSR), DECNCSM, the VT500 private modes, Set-Up selections the host can change and report, terminal ID and mode selection (DECTID, DECTME), secure reset, session names as window titles, 26/42/53-line screens, Greek, Hebrew, Turkish, Cyrillic and ISO Latin-2/5 character sets, modified function and editing keys (DECFNK), key programming by key position (DECPFK, DECPAK, DECCKD and their reports), and dual sessions.
• VT525 — colour: SGR colours, assignable normal and alternate text colours (DECAC, DECATC), colour modes (DECSTGLT) and colour table reports (DECCTR).

Models also differ in how they look: VT52–VT220 use 10×10-dot characters on a 4:3 screen, the VT320, VT420 and VT500 series 10×16-dot characters on their 800×400 raster (see Using veetee).

Every control function, with its status and the manual it follows, is listed in the compatibility matrix.

DEC behaviour first

veetee follows DEC documentation (the programmer references and DEC STD 070) and DEC factory Set-Up defaults, even where xterm and other emulators differ. For example:

• Autowrap is off at power-up and after a soft reset.
• A VT420 and VT510 scroll smoothly at power-up; the VT520 and VT525 jump-scroll.
• Keys click and BEL beeps, at the factory volumes.
• Backspace sends DEL.
• SU and SD pan through page memory rather than scrolling.
• DECSC/DECRC save and restore the autowrap setting.
• Rectangle checksums use the algorithm of the real terminals.

An xterm compatibility setting exists for test suites and Unix software that expect xterm: it makes SU/SD scroll, adds the xterm text-area size report and CSI s/CSI u cursor save and restore, and uses xterm's checksum format. It is not exposed in the GUI yet.