Installing and Using the VT420 Video Terminal

9
VT420 Programming Summary

This chapter is a summary of the control functions and commands described in the VT420 Programmer Reference Manual. Programmers can use this chapter as a quick-reference tool.

NOTE: The application of the control functions and commands on the VT420 affects each session independently.

The chapter is divided into sections that correspond to the chapters of the VT420 Programmer Reference Manual. For example, to find out more about 2 Character Encoding, you would go to Chapter 2 of the VT420 Programmer Reference Manual.

2 Character Encoding

Control Characters

C0 (7-Bit) Control Characters Recognized

Name	Mnemonic Column/Row	Function
Null	`NUL` 0/0	NUL has no function (ignored by the terminal).
Enquiry	`ENQ` 0/5	Sends the answerback message. (Communications Set-Up)
Bell	`BEL` 0/7	Sounds the bell tone if the bell is enabled in the Keyboard Set-Up.
Back space	`BS` 0/8	Moves the cursor one character position to the left. If the cursor is at the left margin, no action occurs.
Horizontal tab	`HT` 0/9	Moves the cursor to the next tab stop. If there are no more tab stops, the cursor moves to the right margin. HT does not cause text to auto wrap.
Line feed	`LF` 0/10	Causes a line feed or a new line operation, depending on the setting of line feed/new line mode.
Vertical tab	`VT` 0/11	Treated as LF.
Form feed	`FF` 0/12	Treated as LF.
Carriage return	`CR` 0/13	Moves the cursor to the left margin on the current line.
Shift out (Locking shift 1)	`SO` (LS1) 0/14	Maps the G1 character set into GL. You designate G1 by using a select character set (SCS) sequence.
Shift in (Locking shift 0)	`SI` (LS0) 0/15	Maps the G0 character set into GL. You designate G0 by using a select character set (SCS) sequence.
Device control 1 (XON)	`DC1` 1/1	Also known as XON. If XON/XOFF flow control is enabled in the Communications Set-Up, DC1 clears DC3 (XOFF). This action causes the VT420 to continue sending characters.
Device control 3 (XOFF)	`DC3` 1/3	Also known as XOFF. If XON/XOFF flow control is enabled in the Communications Set-Up, DC3 causes the VT420 to stop sending characters. The terminal cannot resume sending characters until it receives a DC1 control character.
Device control 4	`DC4` 1/4	Introduces an SSU session management command. The VT420 and host use this control to separate SSU commands from ANSI text and control functions.
Cancel	`CAN` 1/8	Immediately cancels an escape sequence, control sequence, or device control string in progress. The VT420 does not display any error characters.
Substitute	`SUB` 1/10	Immediately cancels an escape sequence, control sequence, or device control string in progress. The VT420 displays a reverse question mark for an error character.
Escape	`ESC` 1/11	Introduces an escape sequence. ESC also cancels any escape sequence, control sequence, or device control string in progress.
Delete	`DEL` 7/15	Ignored when received, unless a 96-character set is mapped into GL. DEL is not used as a fill character. Digital does not recommend using DEL as a fill character. Use NUL instead.

C1 (8-Bit) Control Characters Recognized

Name	Mnemonic Column/Row	Function
Index	`IND` 8/4	Moves the cursor down one line in the same column. If the cursor is at the bottom margin, the page scrolls up.
Next line	`NEL` 8/5	Moves the cursor to the first position on the next line. If the cursor is at the bottom margin, the page scrolls up.
Horizontal tab set	`HTS` 8/8	Sets a horizontal tab stop at the column where the cursor is.
Reverse index	`RI` 8/13	Moves the cursor up one line in the same column. If the cursor is at the top margin, the page scrolls down.
Single shift 2	`SS2` 8/14	Temporarily maps the G2 character set into GL, for the next graphic character. You designate the G2 set by using a select character set (SCS) sequence.
Single shift 3	`SS3` 8/15	Temporarily maps the G3 character set into GL, for the next graphic character. You designate the G3 set by using a select character set (SCS) sequence.
Device control string	`DCS` 9/0	Introduces a device control string. Used for loading function keys or a soft character set.
Start of string	`SOS` 9/8	Ignored.
DEC private identification	`DECID` 9/10	Makes the terminal send its device attributes response to the host (same as an ANSI device attributes (DA) sequence). Programs should use the ANSI DA sequence instead.
NOTE: If the printer is in controller mode, the terminal sends the sequence to the printer.
Control sequence introducer	`CSI` 9/11	Introduces a control sequence.
String terminator	`ST` 9/12	Ends a device control string. You use ST in combination with DCS.
Operating system command	`OSC` 9/13	Introduces an operating system command.*
Privacy message	`PM` 9/14	Introduces a privacy message string.*
Application program command	`APC` 9/15	Introduces an application program command.*
* The VT420 ignores all following characters until it receives a SUB, ST, or any other C1 control character.

8-Bit Control Characters and Their 7-Bit Equivalents

Name	8-Bit Character	7-Bit Sequence
Index	`IND`	`ESC D`
Next line	`NEL`	`ESC E`
Horizontal tab set	`HTS`	`ESC H`
Reverse index	`RI`	`ESC M`
Single shift 2	`SS2`	`ESC N`
Single shift 3	`SS3`	`ESC O`
Device control string	`DCS`	`ESC P`
Start of string	`SOS`	`ESC X`
DEC private identification	`DECID`	`ESC Z`
Control sequence introducer	`CSI`	`ESC [`
String terminator	`ST`	`ESC \`
Operating system command	`OSC`	`ESC ]`
Privacy message	`PM`	`ESC ^`
Application program command	`APC`	`ESC _`

Using Macros

The VT420 lets you define and invoke macros to suit the needs of your application. A macro is a string of ANSI text and commands downloaded into the terminal. By invoking the macro, you can execute a group of control functions with one operation.

Name Mnemonic Sequence

Define macro DECDMAC DCS Pid ; Pdt ; Pen ! z D...D ST

Pid	=	macro ID number (0-63).
Pdt	=	macros to delete first.
0	=	delete all current macros.
1	=	delete all current macros.
Other	=	terminal ignores the macro.
Pen	=	encoding format for macro text.
0	=	standard ASCII characters.
1	=	hex pairs for each ASCII character.
Other	=	terminal ignores the macro.
D...D	=	control string data
!	=	repeat sequence introducer.

Invoke macro DECINVM CSI Pid * z

Pid

macro ID number.

3 Keyboard Codes

Codes Sent by Editing Keys

Key	Code Sent
Key	VT400 Mode	VT100, VT52 Modes
Find	`CSI 1 ~`	The editing keys do not send codes in these two modes.
Insert Here	`CSI 2 ~`
Remove	`CSI 3 ~`
Select	`CSI 4 ~`
Prev	`CSI 5 ~`
Next	`CSI 6 ~`

Codes Sent by Arrow Keys

Key	Cursor Key Mode Setting (DECCKM)
	ANSI Mode*		VT52 Mode*
	Cursor	Application	Cursor or Application
	`CSI A`	`SS3 A`	`ESC A`
	`CSI B`	`SS3 B`	`ESC B`
	`CSI C`	`SS3 C`	`ESC C`
	`CSI D`	`SS3 D`	`ESC D`
* ANSI mode applies to VT400 and VT100 modes. VT52 mode is not compatible with ANSI mode.

Codes Sent by Numeric Keypad Keys

Key	Numeric Keypad Mode Setting (DECNKM)
	ANSI Mode*		VT52 Mode*
	Numeric	Application	Numeric	Application
0	`0`	`SS3 p`	`0`	`ESC ? p`
1	`1`	`SS3 q`	`1`	`ESC ? q`
2	`2`	`SS3 r`	`2`	`ESC ? r`
3	`3`	`SS3 s`	`3`	`ESC ? s`
4	`4`	`SS3 t`	`4`	`ESC ? t`
5	`5`	`SS3 u`	`5`	`ESC ? u`
6	`6`	`SS3 v`	`6`	`ESC ? v`
7	`7`	`SS3 w`	`7`	`ESC ? w`
8	`8`	`SS3 x`	`8`	`ESC ? x`
9	`9`	`SS3 y`	`9`	`ESC ? y`
- (minus)	`-`	`SS3 m`	`-`	`ESC ? m`†
, (comma)	`,`	`SS3 l`	`,`	`ESC ? l`†
. (period)	`.`	`SS3 n`	`.`	`ESC ? n`
Enter	`CR` or `CR LF`‡	`SS3 M`	`CR` or `CR LF`‡	`ESC ? M`
PF1	`SS3 P`	`SS3 P`	`ESC P`	`ESC P`
PF2	`SS3 Q`	`SS3 Q`	`ESC Q`	`ESC Q`
PF3	`SS3 R`	`SS3 R`	`ESC R`	`ESC R`
PF4	`SS3 S`	`SS3 S`	`ESC S`	`ESC S`†
* ANSI mode applies to VT400 and VT100 modes. VT52 mode is not compatible with ANSI standards.
† You cannot use these sequences on a VT52 terminal.
‡ Keypad numeric mode. Enter sends the same codes as Return. You can use line feed/new line mode (LNM) to change the code sent by Return. When LNM is reset, pressing Return sends one control character (CR). When LNM is set, pressing Return sends two control characters (CR, LF).

Codes Sent by the Top-Row Function Keys

Legend	Key Number	Code Sent
Legend	Key Number	VT400 Mode	VT100, VT52 modes
Hold	F1*	--	--
Print	F2*	--	--
Set-Up	F3*	--	--
Session	F4*	--	--
Break	F5*	--	--
F6	F6	`CSI 1 7 ~`	--
F7	F7	`CSI 1 8 ~`	--
F8	F8	`CSI 1 9 ~`	--
F9	F9	`CSI 2 0 ~`	--
F10	F10	`CSI 2 1 ~`	--
F11 (ESC)	F11	`CSI 2 3 ~`	`ESC`
F12 (BS)	F12	`CSI 2 4 ~`	`BS`
F13 (LF)	F13	`CSI 2 5 ~`	`LF`
F14	F14	`CSI 2 6 ~`	--
Help	F15	`CSI 2 8 ~`	--
Do	F16	`CSI 2 9 ~`	--
F17	F17	`CSI 3 1 ~`	--
F18	F18	`CSI 3 2 ~`	--
F19	F19	`CSI 3 3 ~`	--
F20	F20	`CSI 3 4 ~`	--
* F1 through F5 are local function keys that do not send codes.

Keys Used to Send 7-Bit Control Characters

Control Character Mnemonic	Code Table Position	Key Pressed With Ctrl (All Modes)	Dedicated Function Key
NUL	0/00	2 or space bar	--
SOH	0/01	A	--
STX	0/02	B	--
ETX	0/03	C	--
EOT	0/04	D	--
ENQ	0/05	E	--
ACK	0/06	F	--
BEL	0/07	G	--
BS	0/08	H	F12 (BS)*
HT	0/09	I	Tab
LF	0/10	J	F13 (LF)*
VT	0/11	K	--
FF	0/12	L	--
CR	0/13	M	Return
SO	0/14	N	--
SI	0/15	O	--
DLE	1/00	P	--
DC1	1/01	Q†	--
DC2	1/02	R	--
DC3	1/03	S†	--
DC4	1/04	T	--
NAK	1/05	U	--
SYN	1/06	V	--
ETB	1/07	W	--
CAN	1/08	X	--
EM	1/09	Y	--
SUB	1/10	Z	--
ESC	1/11	3 or [	F11 (ESC)*
FS	1/12	4 or /	--
GS	1/13	5 or ]	--
RS	1/14	6 or ~	--
US	1/15	7 or ?	--
DEL	7/15	8	Delete
* 7-bit control characters sent in VT100 or VT52 modes only.
† 7-bit control codes sent only when XON/XOFF support is off.

4 Emulating VT Series Terminals

Selecting an Operating Level (DECSCL)

Sequence	Level Selected
	Level 1
`CSI 6 1 " p`	VT100 mode
	Level 4*
`CSI 6` n `" p`	VT400 mode, 8-bit controls
`CSI 6` n `; 0 " p`	VT400 mode, 8-bit controls
`CSI 6` n `; 1 " p`	VT400 mode, 7-bit controls (D)
`CSI 6` n `; 2 " p`	VT400 mode, 8-bit controls
* Level 4 includes levels 2 and 3. In these sequences, n can be 2 or 3, or 4
(D) = default

Sending C1 Controls to the Host

Sequence	Mode Before	Mode After
7-Bit Controls (S7C1T)
`ESC sp F`	VT400 mode, 8-bit controls	VT400 mode, 7-bit controls
	VT400 mode, 7-bit controls	Same. Terminal ignores sequence.
	VT100 or VT52 mode	Same. Terminal ignores sequence.
8-Bit Controls (S8C1T)
`ESC sp G`	VT400 mode, 8-bit controls	Same. Terminal ignores sequence.
	VT400 mode, 7-bit controls	VT400 mode, 8-bit controls
	VT100 or VT52 mode	Same. Terminal ignores sequence.

Character Set Mode (DECNRCM)

(Worldwide Model Only)
Default: Multinational

Mode	Sequence	Function
Set (national)	`CSI ? 4 2 h`	The terminal uses 7-bit characters from an NRC set.
Reset (multinational)	`CSI ? 4 2 l`*	The terminal uses 7-bit and 8-bit characters from the DEC Multinational or ISO Latin-1 set.
* The last character in the sequence is a lowercase L.

5 Using Character Sets

Selecting Graphic Character Sets

Designate the set as G0, G1, G2, or G3.
Map the designated set into the in-use table.

Designating Character Sets (SCS Sequences)

You designate a hard character set as G0 through G3 by using a select character set (SCS) escape sequence. You cannot designate a 96-character set as G0.

Format:

ESC I₁ I₂ ... I_n F

I₁, intermediate character
Designates the character set as G0, G1, G2, or G3.

I₁ Character		Code	Set Selection
94-Character Sets
(	left parenthesis	2/8	G0 (initial setting for GL)
)	right parenthesis	2/9	G1
*	asterisk	2/10	G2 (initial setting for GR)
+	plus sign	2/11	G3
96-Character Sets*
-	hyphen	2/13	G1
.	period	2/14	G2
/	slash	2/15	G3
* You cannot designate a 96-character set into G0.

I₂...I_n F, intermediate and final characters
Selects one of the standard character sets.

Character Set	I₂...I_n F Characters	Code
94-Character Sets
ASCII (initial G1 and G0 setting)	B	4/2
DEC Supplemental Graphic (initial G2 and G3 setting)	%5	2/5, 3/5
DEC Special Graphics	0	3/0
DEC Technical	>	3/14
User-preferred supplemental	<	3/12
NRC Sets*
ISO United Kingdom	A	4/1
DEC Dutch	4	3/4
DEC Finnish	5	3/5
ISO French	R	5/2
DEC French Canadian	9	3/9
ISO German	K	4/11
ISO Italian	Y	5/9
DEC Norwegian/Danish	6	3/6
ISO Norwegian/Danish	`	6/0
DEC Portuguese	%6	2/5, 3/6
ISO Spanish	Z	5/10
DEC Swedish	7	3/7
DEC Swiss	=	3/13
96-Character Sets
ISO Latin-1 Supplemental	A	4/1
* Only one NRC set is available at a time. You must select national mode to use NRC sets. See "Character Set Mode (DECNRCM)" at the end of "4 Emulating VT Series Terminals".

Mapping Character Sets

After you designate a character set as G0, G1, G2, or G3, you must map the set into the in-use table as GL or GR. To map a set, you use locking-shift or single-shift control functions.

To use a national replacement character set, you must select national replacement character set mode. When you reset this mode, the terminal uses 7-bit and 8-bit characters from one of the multinational character sets (DEC Multinational or ISO Latin-1). When you set this mode, the terminal uses 7-bit characters from an NRC set.

See "Character Set Mode (DECNRCM)" at the end of "4 Emulating VT Series Terminals".

Locking Shifts (LS)

When you use a locking shift, the character set remains in GL or GR until you use another locking shift.

Name	Mnemonic	Code	Maps...
Locking shift G0	LS0	`SI`	Maps G0 into GL. (default)
Locking shift G1	LS1	`SO`	G1 into GL.
The following locking shift functions are available only in VT400 mode.
Locking shift G1 right	LS1R	`ESC ~`	G1 into GR.
Locking shift G2	LS2	`ESC n`	G2 into GL.
Locking shift G2 right	LS2R	`ESC }`	G2 into GR.
Locking shift G3	LS3	`ESC o`	G3 into GL.
Locking shift G3 right	LS3R	`ESC \|`	G3 into GR.

Single Shifts (SS)

You use a single shift when you want to display the next character from a different character set. A single shift maps the G2 or G3 set into GL. The character set is active for only one character. Then the terminal returns to the previous character set in GL.

Name	8-Bit Code	7-Bit Code	Function
Single shift 2	`SS2`	`ESC N`	Maps G2 into GL for the next character.
Single shift 3	`SS3`	`ESC O`	Maps G3 into GL for the next character.

Assigning User-Preferred Supplemental Sets (DECAUPSS)

Default: DEC Supplemental Graphic

Sequence	Set Selected
`DCS 0 ! u % 5 ST`	DEC Supplemental Graphic
`DCS 1 ! u A ST`	ISO Latin-1 Supplemental

ANSI Conformance Levels

ESC sp Final

Final	ANSI Conformance Level
`L`	Level 1
`M`	Level 2
`N`	Level 3

Soft Character Sets

You can only load soft character sets in VT400 mode.

Character Cell Sizes

Cell Size	80 Columns	132 Columns
24 lines/screen
Width	10 pixels	6 pixels
Height	16	16
36 lines/screen
Width	10	6
Height	10	10
48 lines/screen
Width	10	6
Height	8	8

Converting Binary Code to an ASCII Character

Binary Value	Hex Value	Hex Value + 3F Offset	Character Equivalent
000000	00	3F	?
000001	01	40	@
000010	02	41	A
000011	03	42	B
000100	04	43	C

000101	05	44	D
000110	06	45	E
000111	07	46	F
001000	08	47	G
001001	09	48	H

001010	0A	49	I
001011	0B	4A	J
001100	0C	4B	K
001101	0D	4C	L
001110	0E	4D	M

001111	0F	4E	N
010000	10	4F	O
010001	11	50	P
010010	12	51	Q
010011	13	52	R

010100	14	53	S
010101	15	54	T
010110	16	55	U
010111	17	56	V
011000	18	57	W

011001	19	58	X
011010	1A	59	Y
011011	1B	5A	Z
011100	1C	5B	[
011101	1D	5C	\

011110	1E	5D	]
011111	1F	5E	^
100000	20	5F	_
100001	21	60	`
100010	22	61	a

100011	23	62	b
100100	24	63	c
100101	25	64	d
100110	26	65	e
100111	27	66	f

101000	28	67	g
101001	29	68	h
101010	2A	69	i
101011	2B	6A	j
101100	2C	6B	k

101101	2D	6C	l
101110	2E	6D	m
101111	2F	6E	n
110000	30	6F	o
110001	31	70	p

110010	32	71	q
110011	33	72	r
110100	34	73	s
110101	35	74	t
110110	36	75	u

110111	37	76	v
111000	38	77	w
111001	39	78	x
111010	3A	79	y
111011	3B	7A	z

111100	3C	7B	{
111101	3D	7C	\|
111110	3E	7D	}
111111	3F	7E	~

Downloading Soft Characters

Use the following sequence format:

DCS Pfn; Pcn; Pe; Pcmw; Pss; Pt; Pcmh; Pcss { Dscs Sxbp1 ; Sxbp2 ;...; Sxbpn ST

DECDLD Parameter Characters

Parameter

Name

Description

Pfn

Font number

Selects the DRCS font buffer to load. Each session has only one font buffer. Pfn has two valid values, 0 and 1. Both values refer to DRCS buffer 1 for each session.

Pcn

Starting character

Selects where to load the first character in the DRCS font buffer. The location corresponds to a location in the ASCII code table. For example, a Pcn value of 0 means that the first soft character is loaded into position 2/0 of the character table. A Pcn value of 1 means position 2/1 in the table, and so on up to Pcn = 95 (position 7/15).

Pcn is affected by the character set size. See Pcss below.

Erase control

Selects which characters to erase from the DRCS buffer before loading the new font.

0	=	erase all characters in the DRCS buffer with this number, width and rendition.
1	=	erase only characters in locations being reloaded.
2	=	erase all renditions of the soft character set (normal, bold, 80-column, 132-column).

NOTE: Erased characters are undefined (not blank). The terminal displays these characters as the error character (reverse question mark).

Pcmw

Character matrix width

Selects the maximum character cell width.

0	=	10 pixels wide for 80 columns, 6 pixels wide for 132 columns. (default)
1	=	illegal.
2	=	5 × 10 pixel cell (VT220 compatible).
3	=	6 × 10 pixel cell (VT220 compatible).
4	=	7 × 10 pixel cell (VT220 compatible).
5	=	5 pixels wide.
6	=	6 pixels wide.
.
.
.
10	=	10 pixels wide.

Pss

Font set size

Defines the screen width and screen height for this font.

0, 1	=	80 columns, 24 lines. (default)
2	=	132 columns, 24 lines
11	=	80 columns, 36 lines
12	=	132 columns, 36 lines
21	=	80 columns, 48 lines
22	=	132 columns, 48 lines

If the number of columns or lines per screen changes, the terminal uses the appropriate variation of the soft set. If you try to display a DRCS character when there is no soft set defined for the current number of lines and columns, the terminal displays the error character (reverse question mark).

Text or full cell

Defines the font as a text font or full-cell font.

0	=	text. (default)
1	=	text.
2	=	full cell.

Full-cell fonts can individually address all pixels in a cell.

Text fonts cannot individually address all pixels. If you specify a text cell, the terminal automatically performs spacing and centering of the characters.

Pcmh

Character matrix height

Selects the maximum character cell height.

0 or omitted	=	16 pixels high. (default)
1	=	1 pixel high.
2	=	2 pixels high.
3	=	3 pixels high.
.
.
16	=	16 pixels high.

Pcmh values over 16 are illegal. If the value of Pcmw is 2, 3, or 4, Pcmh is ignored.

Pcss

Character set size

Defines the character set as a 94- or 96-character graphic set.

0	=	94-character set. (default)
1	=	96-character set.

The value of Pcss changes the meaning of the Pcn (starting character) parameter above.

Examples

If Pcss = 0 (94-character set)

The terminal ignores any attempt to load characters into the 2/0 or 7/15 table positions.

Pcn Specifies

1 column 2/row 1

.

.

94 column 7/row 14
If Pcss = 1 (96-character set)

Pcn Specifies

0 column 2/row 0

.

.

95 column 7/row 15

Dscs
defines the name for the soft character set. You use this name in the select character set (SCS) escape sequence. You use the following format for the Dscs name:

I F

`I`	is 0, 1 or 2 intermediate characters from the range 2/0 to 2/15 in the ASCII character set.
`F`	is a final character in the range 3/0 to 7/14.

Sxbp1 ; Sxbp2 ; ... ; Sxbpn
are the sixel bit patterns for individual characters, separated by semicolons (3/11). Your character set can have 1 to 94 patterns or 1 to 96 patterns, depending on the setting of the character set size parameter (Pcss). Each sixel bit pattern is in the following format:

S...S/S...S

the first S...S
represents the upper columns of the soft character.

/ (2/5)
advances the sixel pattern to the lower columns of the soft character.

the second S...S
represents the sixels in the lower columns of the soft character.

ST
is the string terminator. ST is an 8-bit C1 character. You can use the equivalent 7-bit sequence ESC \ (1/11, 5/12) when coding for a 7-bit environment.

Valid DECDLD Parameter Combinations

Pt	Pcmw	Pcmh	Pss*
80-column, 24 lines
0 or 1	0 to 8	0 to 16	0 or 1
2	0 to 10	0 to 16	0, 1

132-column, 24 lines
0 or 1	0 to 5	0 to 16	2
2	0 to 6	1 to 16	2

80-column, 36 lines
0 or 1	0 to 8	0 to 10	11
2	0 to 10	0 to 10	11

132-column, 36 lines
0 or 1	0 to 5	0 to 10	12
2	0 to 6	0 to 10	12

80-column, 48 lines
0 or 1	0 to 8	0 to 8	21
2	0 to 10	0 to 8	21

132-column, 48 lines
0 or 1	0 to 5	0 to 8	22
2	0 to 6	0 to 8	22
* The default values are the maximum legal values in each case.

Clearing a Soft Character Set

You can clear a soft character set that you loaded into the terminal by using the following DECDLD control string:

DCS 1;1;2 { sp @ ST

Any of the following actions also clear the soft character set:

Performing the power-up self-test.
Selecting Recall or Default in the Set-Up Directory.
Using a reset to initial state (RIS) sequence.

6 Page Memory

Setting the Page Format

Name Mnemonic Sequence

Set columns per page DECSCPP CSI Pn $ |
Pn columns (80 or 132).

Column mode DECCOLM Set: CSI ? 3 h
132 columns.

Reset: CSI ? 3 l
80 columns. (D)

Set lines per page

DECSLPP

CSI Pn t
Pn lines per page.
The number of pages depend on how many sessions you use.

Pn	Dual Sessions	Single Session
24	3 pages	6 pages
25	2	5
36	2	4
48	1	3
72	1	2
144	--	1

Set left and right margins DECSLRM CSI Pl ; Pr s
Pl = left column.
Pr = right column.

Set top and bottom margins DECSTBM CSI Pt ; Pb r
Pt = top line.
Pb= bottom line.

Origin mode DECOM Set: CSI ? 6 h
Move within margins.

Reset: CSI ? 6 l
Move outside margins. (D)

Vertical split screen mode DECVSSM Set: CSI ? 69 h
Left and right margins can be changed.

Reset: CSI ? 69 l
Left and right margins cannot be changed. (D)

(D) = default.

Moving Through Page Memory

Name	Mnemonic	Sequence*
Next page	NP	`CSI` Pn `U` Move Pn pages forward. C = home.
Preceding page	PP	`CSI` Pn `V` Move Pn pages backward. C = home.
Page position absolute	PPA	`CSI` Pn `sp P` Move to page Pn. C = same as old page.
Page position backward	PPB	`CSI` Pn `sp R` Move Pn pages backward. C = same as old page.
Page position relative	PPR	`CSI` Pn `sp Q` Move Pn pages forward. C = same as old page.
* C = new cursor position.

7 Visual Character and Line Attributes

Character and Line Attribute Sequences

Name	Mnemonic	Sequence
Select graphic rendition	SGR	`CSI` Ps...Ps `m` Ps = character attribute value(s). (See the list below.)
Single-width, single-height line	DECSWL	`ESC # 5`
Double-width, single-height line	DECDWL	`ESC # 6`
Double-width, double-height line	DECDHL	`ESC # 3` (top half) `ESC # 4` (bottom half)

Visual Character Attribute Values

Ps	Attribute
VT100 or VT400 Mode
0	All attributes off
1	Bold
4	Underline
5	Blinking
7	Reverse video
VT400 Mode Only
22	Bold off
24	Underline off
25	Blinking off
27	Reverse video off

8 Editing

Editing Sequences

Name Mnemonic Sequence

Insert/replace mode IRM Set: CSI 4 h
Insert characters.

Reset: CSI 4 l
Replace characters.

Delete column DECDC CSI Pn ' ~
Pn columns.

Insert column DECIC CSI Pn ' }
Pn columns.

Delete line DL CSI Pn M
Pn lines.

Insert line IL CSI Pn L

Delete character DCH CSI Pn P
Pn characters.

Insert character ICH CSI Pn @
Pn characters.

Erase in display ED CSI Ps J

Ps	=	0, cursor to end. (D)
Ps	=	1, beginning to cursor.
Ps	=	2, complete display.

Erase in line EL CSI Ps K

Ps	=	0, cursor to end. (D)
Ps	=	1, beginning to cursor.
Ps	=	2, complete line.

Erase character* ECH CSI Pn X
Pn characters.

Select character protection attribute* DECSCA CSI Ps " q

Ps	=	0, DECSED and DECSEL can erase. (D)
Ps	=	1, DECSED and DECSEL cannot erase.
Ps	=	2, DECSED and DECSEL can erase.

Selective erase in display* DECSED CSI ? Ps J

Ps	=	0, cursor to end. (D)
Ps	=	1, beginning to cursor.
Ps	=	2, complete display.

Selective erase in line* DECSEL CSI ? Ps K

Ps	=	0, cursor to end. (D)
Ps	=	1, beginning to cursor.
Ps	=	2, complete line.

* Available in VT400 mode only.
(D) = default

9 Rectangular Area Operations

Rectangular Area Control Functions

Name Mnemonic Sequence*

Copy rectangular area DECCRA CSI Pts; Pl; Pbs; Prs; Pps; Ptd; Pld; Ppd $ v

Pts	=	top-line border.
Pl	=	left-column border.
Pbs	=	bottom-line border.
Prs	=	right-column border.
Pps	=	source page number.
Ptd	=	destination top-line border.
Pld	=	destination left-column border.
Ppd	=	destination page number.

Erase rectangular area DECERA CSI Pt; Pl; Pb; Pr $ z

Pt	=	top-line border.
Pl	=	left-column border.
Pb	=	bottom-line border.
Pr	=	right-column border.

Fill rectangular area DECFRA CSI Pch; Pt; Pl; Pb; Pr $ x

Pch	=	decimal code of fill character.
Pt	=	top-line border.
Pl	=	left-column border.
Pb	=	bottom-line border.
Pr	=	right-column border.

Selective erase rectangular area DECSERA CSI Pt; Pl; Pb; Pr $ {

Pt	=	top-line border.
Pl	=	left-column border.
Pb	=	bottom-line border.
Pr	=	right-column border.

Select attribute change extent DECSACE CSI Ps * x

Ps	=	character positions affected.
0 or 1	=	stream of character positions.
2	=	rectangular area of character positions.

Change attributes in rectangular area DECCARA CSI Pt; Pl; Pb; Pr; Ps1..Psn $ r

Pt	=	top-line border.
Pl	=	left-column border.
Pb	=	bottom-line border.
Pr	=	right-column border.
Psn	=	visual character attributes.

Reverse attributes in rectangular area DECRARA CSI Pt; Pl; Pb; Pr; Ps1..Psn $ t

Pt	=	top-line border.
Pl	=	left-column border.
Pb	=	bottom-line border.
Pr	=	right-column border.
Psn	=	visual character attributes.

* These sequences work in VT400 mode only.

10 Cursor Movement and Panning

Cursor Movement and Panning Sequences

Name	Mnemonic	Sequence
Enabling the Cursor
Text cursor enable mode	DECTCEM	Set: `CSI ? 25 h` Visible cursor. (D)
Text cursor enable mode	DECTCEM	Reset: `CSI ? 25 l` Invisible cursor.
Moving the Cursor*
Back index†	DECBI	`ESC 6`
Forward index†	DECFI	`ESC 9`
Cursor position	CUP	`CSI` Pl ; Pc `H` Line Pl, column Pc.
Horizontal and vertical position	HVP	`CSI` Pl ; Pc `f` Line Pl, column Pc. (Digital recommend using CUP instead.)
Cursor forward	CUF	`CSI` Pn `C` Pn columns right.
Cursor backward	CUB	`CSI` Pn `D` Pn columns left.
Cursor up	CUU	`CSI` Pn `A` Pn lines up.
Cursor down	CUD	`CSI` Pn `B` Pn lines down.
Panning*
Pan down	SU	`CSI` Pn `S` Pn lines down.
Pan up	SD	`CSI` Pn `T` Pn lines up.
Vertical cursor coupling mode	DECVCCM	Set: `CSI ? 61 h` Coupled. (D)
Vertical cursor coupling mode	DECVCCM	Reset: `CSI ? 61 l` Uncoupled.
Page cursor coupling mode	DECPCCM	Set: `CSI ? 64 h` Coupled. (D)
Page cursor coupling mode	DECPCCM	Reset: `CSI ? 64 l` Uncoupled.
* In these sequences, the default value for Pn, Pl, and Pc is 1.
† Available in VT400 mode only.
(D) = default.

11 Keyboard, Printing, and Display Commands

Keyboard Control Sequences

Mode	Mnemonic	Sequence
Mode	Mnemonic	Set	Reset
Keyboard action	KAM	`CSI 2 h` Locked.	`CSI 2 l` Unlocked. (D)
Backarrow key	DECBKM	`CSI ? 67 h` Backspace.	`CSI ? 67 l` Delete. (D)
Line feed/ new line	LNM	`CSI 20 h` New Line.	`CSI 20 l` Line feed. (D)
Autorepeat	DECARM	`CSI ? 8 h` Repeat. (D)	`CSI ? 8 l` No repeat.
Autowrap	DECAWM	`CSI ? 7 h` Autowrap.	`CSI ? 7 l` No autowrap. (D)
Cursor keys	DECCKM	`CSI ? 1 h` Application.	`CSI ? 1 l` Cursor. (D)
Keypad application/ numeric	DECKPAM	`ESC =` Application.	`ESC >` Numeric. (D)
Numeric keypad mode	DECNKM	`CSI ? 66 h` Application.	`CSI ? 66 l` Numeric. (D)
Keyboard usage mode	DECKBUM	`CSI ? 68 h` Data processing.	`CSI ? 68 l` Typewriter. (D)
Key position	DECKPM	`CSI ? 81 h` Position reports.	`CSI ? 81 l` Character codes. (D)

Name Mnemonic Sequence

Enable local functions DECELF CSI Pf1; Pc1; ... Pfn; Pcn + q

Pfn	=	function number.
0	=	all local functions.
1	=	local copy and paste.
2	=	local panning.
3	=	local window resize.
Pcn	=	control performed.
0	=	factory default.
1	=	enable local function.
2	=	disable local function.

Local function key control DECLFKC CSI Pk1; Pf1; ... Pkn; Pfn * }

Pkn	=	function key number.
0	=	all local function keys.
1	=	F1 or Hold.
2	=	F2 or Print.
3	=	F3 or Set-Up.
4	=	F4 or Session.
Pfn	=	function performed.
0	=	factory default.
1	=	local function.
2	=	send key sequence.
3	=	disable key.

Select modifier key reporting DECSMKR CSI Pm1; Pf1; ... Pmn; Pfn + r

Pmn	=	key number.
0	=	all keys.
1	=	left Shift.
2	=	right Shift.
3	=	lock key.
4	=	Ctrl.
5	=	left Alt Function.
6	=	right Alt Function.
7	=	left Compose Character.
8	=	right Compose Character.
Pcn	=	control performed.
0	=	factory default.
1	=	modifier function.
2	=	extended keyboard report.
3	=	key disabled.

Extended keyboard report DECEKBD APC : ppp mm ST

ppp	=	key position number.
mm	=	modifier key state.
0	=	not pressed.
1	=	pressed.

(D) = default.

Programming UDKs

Definable Keys

F6 through F14	Help
Do	F17 through F20

DECUDK Device Control String Format

DCS Pc ; Pl | Ky1/St1; ... Kyn/Stn ST

Pc is the clear parameter.
0 or none	=	clear all keys before loading new values (default).
1	=	clear one key at a time, before loading a new value.
Pl is the lock parameter.
0 or none	=	lock the keys.
1	=	do not lock the keys.

Ky1/St1;...Kyn/Stn are the key definition strings.

The key selector number (Kyn) indicates which key you are defining.

Key	Value	Key	Value	Key	Value
F6	17	F11	23	Do	29
F7	18	F12	24	F17	31
F8	19	F13	25	F18	32
F9	20	F14	26	F19	33
F10	21	Help	28	F20	34

The string parameters (Stn) are the key definitions, encoded as pairs of hex codes.

3/0 through 3/9 (0 through 9)

4/1 through 4/6 (A through F)

6/1 through 6/6 (a through f)

Printing Control Sequences

Name	Mnemonic	Sequence
Printer extent mode	DECPEX	Set: `CSI ? 19 h` Page. (D)
Printer extent mode	DECPEX	Reset: `CSI ? 19 l` Scrolling region.
Print form feed mode	DECPFF	Set: `CSI ? 18 h` Form feed.
Print form feed mode	DECPFF	Reset: `CSI ? 18 l` No form feed. (D)
Auto print mode	MC	On: `CSI ? 5 i` Off: `CSI ? 4 i`
Printer controller mode	MC	On: `CSI 5 i` Off: `CSI 4 i`
Print page	MC	`CSI i` or `CSI 0 i`
Print composed main display	MC	`CSI ? 10 i`
Print all pages	MC	`CSI ? 11 i`
Print cursor line	MC	`CSI ? 1 i`
Start printer-to-host session	MC	`CSI ? 9 i`
Stop printer-to-host session	MC	`CSI ? 8 i`
Assign printer to active session	MC	`CSI ? 18 i`
Release printer	MC	`CSI ? 19 i`
Send line attributes	--
Single-width		`ESC # 5`
Double-width		`ESC # 6`
Double-width/double-height
Top half		`ESC # 3`
Bottom half		`ESC # 4`
Send visual character attributes	--
Clear all attributes		`ESC [ 0 m`
Set attributes		`ESC [ 0;` Ps; Ps; ... Ps `m` Ps = attribute. See text.
(D) = default.

Screen Display Control Sequences

Name	Mnemonic	Sequence
Send/receive mode	SRM	Set: `CSI 12 h` Local echo off. (D)
Send/receive mode	SRM	Reset: `CSI 12 l` Local echo on.
Screen mode	DECSCNM	Set: `CSI ? 5 h` Light background.
Screen mode	DECSCNM	Reset: `CSI ? 5 l` Dark background. (D)
Scrolling mode	DECSCLM	Set: `CSI ? 4 h` Smooth scroll. (D)
Scrolling mode	DECSCLM	Reset: `CSI ? 4 l` Jump scroll.
Select number of lines per screen	DECSNLS	`CSI Pn * \|` Pn = number of lines.
Select active status display*	DECSASD	`CSI Ps $ }` Ps = 0, main display. Ps = 1, status line.
Select status line type*	DECSSDT	`CSI Ps $ ~` Ps = 0, none. Ps = 1, indicator. (D) Ps = 2, host-writable.
* Available in VT400 mode only.
(D) = default.

12 VT420 Reports

Sequences for VT420 Reports

Name Mnemonic Sequence

Primary Device Attributes

Primary DA request
(Host to VT420) DA CSI c or CSI 0 c

Primary DA response
(VT420 to Host) DA CSI ? Psc; Ps1; ... Psn c

Psc	=	operating level.
61	=	level 1 (VT100 family).
62,63,64	=	level 4 (VT400 family).
Ps1...Psn	=	extensions.
1	=	132 columns.
2	=	printer port.
6	=	selective erase.
7	=	soft character set.
8	=	user-defined keys.
9	=	NRC sets.
15	=	DEC technical set.
18	=	user windows.
19	=	two sessions.
21	=	horizontal scrolling.
See Table 9-1 for alias responses.

Secondary Device Attributes

Secondary DA request
(Host to VT420) DA CSI > c or CSI > 0 c

Secondary DA response
(VT420 to Host)

CSI > 41; Pv ; 0 c

Pv = firmware version.

Tertiary Device Attributes (VT400 Mode Only)

Tertiary DA request
(Host to VT420) DA CSI = c or CSI = 0 c

DECRPTUI response
(VT420 to host)

DCS ! | D...D ST

D...D = unit ID.

Device Status Reports

VT420 Operating Status

Request
(Host to VT420) DSR CSI 5 n

Report
(VT420 to Host) DSR CSI 0 n
No malfunction.

CSI 3 n
Malfunction.

Cursor Position Report

Request
(Host to VT420) DSR CSI 6 n

Report
(VT420 to Host) CPR CSI Pl; Pc R

Pl	=	line number.
Pc	=	column number.

Extended Cursor Position Report

Request
(Host to VT420) DSR CSI ? 6 n

Report
(VT420 to host) DECXCPR CSI ? Pl; Pc; Pp R

Pl	=	line number.
Pc	=	column number.
Pp	=	page number.

Printer Status

Request
(Host to VT420) DSR CSI ? 15 n

Report
(VT420 to host) DSR CSI ? 13 n
No printer.

CSI ? 10 n
Printer ready.

CSI ? 11 n
Printer not ready.

CSI ? 18 n
Printer busy.

CSI ? 19 n
Printer assigned to other session.

UDK Status (VT400 Mode Only)

Request
(Host to VT420) DSR CSI ? 25 n

Report
(VT420 to host) DSR CSI ? 20 n
UDKs unlocked.

CSI ? 21 n
UDKs locked.

Keyboard Status

Request
(Host to VT420) DSR CSI ? 26 n

Report
(VT420 to host) DSR CSI ? 27; Pla; Pst; Ptyp n

Pla	=	keyboard dialect.
1	=	North American.
2	=	British.
3	=	Flemish.
4	=	French Canadian.
5	=	Danish.
6	=	Finnish.
7	=	German.
8	=	Dutch.
9	=	Italian.
10	=	Swiss French.
11	=	Swiss German.
12	=	Swedish.
13	=	Norwegian.
14	=	French/Belgian.
15	=	Spanish.
16	=	Portuguese.
28	=	Canadian (English).

Pst	=	keyboard status.
0	=	keyboard ready.
3	=	no keyboard.
8	=	keyboard busy.

Ptyp	=	keyboard type.
0	=	LK201.
1	=	LK401

Macro Space

Request
(Host to VT420) DSR CSI ? 62 n

Report
(VT420 to host) DECMSR CSI Pn * {
Pn = number of bytes / 16.

Memory Checksum

Request
(Host to VT420) DSR CSI ? 63; Pid n
Pid = request label.

Report
(VT420 to host)

DECCKSR

DCS Pid ! ~ D..D ST

Pid	=	request label.
D..D	=	checksum.

Data Integrity

Request
(Host to VT420) DSR CSI ? 75 n

Report
(VT420 to host) DSR CSI ? 70 n
No communication errors.

CSI ? 71 n
Communication errors.

CSI ? 73 n
Not reported since last power-up or RIS.

Multiple Session Status

Request
(Host to VT420) DSR CSI ? 85 n

Report
(VT420 to host) DSR CSI ? 80; Ps2 n
SSU sessions enabled.
Ps2 = Maximum number of sessions.

CSI ? 81; Ps2 n
SSU sessions available but pending.
Ps2 = Maximum number of sessions.

CSI ? 83 n
SSU sessions not ready.

CSI ? 87 n
Sessions on separate lines.

Requesting Checksum of Rectangular Area
(VT400 Mode Only)

Request
(Host to VT420) DECRQCRA CSI Pid; Pp; Pt; Pl; Pb; Pr * y

Pid	=	request label.
Pp	=	page number.
Pt	=	top-line border.
Pl	=	left-column border.
Pb	=	bottom-line border.
Pr	=	right-column border.

Checksum report
(VT420 to host)

DECCKSR

DCS Pid ! ~ D...D ST

Pid	=	request label.
D...D	=	checksum.

Terminal State Reports (VT400 Mode Only)

Request (Host to VT420) DECRQTSR CSI Ps $ u

Ps	=	report requested.
0	=	ignored.
1	=	terminal state report.

Terminal state report
(VT420 to host) DECTSR DCS 1 $ s D..D ST
D...D = report data.

Restore DECRSTS DCS Ps $ p D...D ST

Ps	=	data string format.
0	=	error.
1	=	terminal state report.
D...D	=	restored data.

Presentation State Reports (VT400 Mode Only)

Request
(Host to VT420) DECRQPSR CSI Ps $ w

Ps	=	report requested.
0	=	error.
1	=	cursor information report.
2	=	tab stop report.

Cursor information report
(VT420 to Host)

DECCIR

DCS 1 $ u D...D ST

D...D = data string.

See the VT420 Programmer Reference Manual for description.

Tab stop report
(VT420 to host) DECTABSR DCS 2 $ u D...D ST
D...D = tab stops.

Restore DECRSPS DCS Ps $ t D...D ST

Ps	=	data string format.
0	=	error.
1	=	cursor information report.
2	=	tab stop report.
D...D	=	data string.

Mode Settings (VT400 Mode Only)

Request mode
(Host to VT420) DECRQM CSI Pa $ p

ANSI mode. (Table 9-2)

CSI ? Pd $ p

DEC private mode. (Table 9-3)

Report mode
(VT420 to host) DECRPM CSI Pa; Ps $ y

Pa	=	ANSI mode. (Table 9-2)
Ps	=	mode state.
0	=	unknown mode.
1	=	set.
2	=	reset.
3	=	permanently set.
4	=	permanently reset.

Set mode SM CSI Pa; ... Pa h

ANSI mode(s). (Table 9-2)

CSI ? Pd; ... Pd h

DEC private mode(s). (Table 9-3)

Reset mode RM CSI Pa; ... Pa l

ANSI mode(s). (Table 9-2)

CSI ? Pd; ... Pd l

DEC private mode(s). (Table 9-3)

Control Function Settings (VT400 Mode Only)

Request
(Host to VT420) DECRQSS DCS $ q D...D ST

D...D

intermediate and/or final characters of function. (Table 9-4)

Report
(VT420 to host) DECRPSS DCS Ps $ r D...D ST

Ps	=	0, valid request.
Ps	=	1, invalid request.
D...D	=	intermediate and/or final characters of function. (Table 9-4)

Saving and Restoring the Cursor State

Save cursor state DECSC ESC 7

Restore cursor state DECRC ESC 8

Window Report (VT400 Mode Only)

Request
(Host to VT420) DECRQDE CSI " v

Report
(VT420 to host) DECRPDE CSI Ph; Pw; Pml; Pmt; Pmp " w

Ph	=	number of lines.
Pw	=	number of columns.
Pml	=	first column at left.
Pmt	=	top line.
Pmp	=	page number.

User-Preferred Supplemental Set (VT400 Mode)

Request
(Host to VT420) DECRQUPSS CSI & u

Report
(VT420 to host) DECAUPSS DCS 0 ! u % 5 ST
DEC Supplemental Graphic

DCS 1 ! u A ST
ISO Latin-1 Supplemental

Table 9-1 Alias Primary DA Responses from the VT420
Terminal	Identification Sequence	Meaning
VT100 DA	`ESC [ ? 1; 2 c`	VT100 terminal
VT101 DA	`ESC [ ? 1; 0 c`	VT101 terminal
VT102 DA	`ESC [ ? 6 c`	VT102 terminal
VT220 DA*	`CSI ? 62; 1; 2; 6; 7; 8; 9 c`	VT220 terminal
VT320 DA*	`CSI ? 63; 1; 2; 6; 7; 8; 9 c`	VT320 terminal
VT420 DA*	`CSI ? 64; 1; 2; 6; 7; 8; 9; 15; 18; 19; 21 c`	VT420 terminal
NOTE: To change an alias response, you must use the General Set-Up screen. See Chapter 5, "Using Set-Up".
* These responses correspond to the international model of the terminal. The North American model does not support NRC sets (9).

Table 9-2 ANSI Modes for DECRQM, DECRPM, SM, and RM
Mode	Mnemonic	Pa
Guarded area transfer	GATM*	1
Keyboard action	KAM	2
Control representation	CRM†	3
Insert/replace	IRM	4
Status reporting transfer	SRTM*	5
Vertical editing	VEM*	7
Horizontal editing	HEM*	10
Positioning unit	PUM*	11
Send/receive	SRM	12
Format effector action	FEAM*	13
Format effector transfer	FETM*	14
Multiple area transfer	MATM*	15
Transfer termination	TTM*	16
Selected area transfer	SATM*	17
Tabulation stop	TSM*	18
Editing boundary	EBM*	19
Line feed/new line	LNM	20
* This control function is permanently reset.
† The host cannot change the setting of CRM. You can only change CRM from set-up. If CRM is set, the terminal ignores DECRQM and most other control functions.

Table 9-3 DEC Private Modes for DECRQM, DECRPM, SM, and RM
Mode	Mnemonic	Pd
Cursor keys	DECCKM	1
ANSI	DECANM	2
Column	DECCOLM	3
Scrolling	DECSCLM	4
Screen	DECSCNM	5
Origin	DECOM	6
Autowrap	DECAWM	7
Autorepeat	DECARM	8
Print form feed	DECPFF	18
Printer extent	DECPEX	19
Text cursor enable	DECTCEM	25
National replacement character set	DECNRCM	42
Horizontal cursor coupling	DECHCCM†	60
Vertical cursor coupling	DECVCCM	61
Page cursor coupling	DECPCCM	64
Numeric keypad	DECNKM	66
Backarrow key	DECBKM	67
Keyboard usage	DECKBUM	68
Vertical split screen	DECVSSM	69
Transmit rate limiting	DECXRLM	73
Keyboard position	DECKPM	81
† This control function is permanently reset.

Table 9-4 Control Functions for DECRQSS Requests
Control Function	Mnemonic	Intermediate and Final Character(s)
Select active status display	DECSASD	`$ }`
Select attribute change extent	DECSACE	`* x`
Set character attribute	DECSCA	`" q`
Set conformance level	DECSCL	`" p`
Set columns per page	DECSCPP	`$ \|`
Set lines per page	DECSLPP	`t`
Set number of lines per screen	DECSNLS	`* \|`
Set status line type	DECSSDT	`$ ~`
Set left and right margins	DECSLRM	`s`
Set top and bottom margins	DECSTBM	`r`
Select graphic rendition	SGR	`m`
Enable local functions	DECELF	`+ q`
Local function key control	DECLFKC	`* }`
Select modifier key reporting	DECSMKR	`+ r`

13 Resetting and Testing the Terminal

Resetting and Testing Sequences

Name Mnemonic Sequence

Resetting the Terminal

Soft terminal reset* DECSTR CSI ! p

Hard terminal reset RIS ESC c
Not recommended.

Secure reset DECSR ESC [ Pr + p
Pr can be any number from 0 to 16383.

Secure reset confirmation DECSRC ESC [ Pr * q
Pr can be any number from 0 to 16383.

Tabulation clear TBC CSI 0 g
Clear tab at cursor position.

CSI 3 g
Clear all tabs.

Testing the Terminal

Screen alignment display DECALN ESC # 8

Invoke confidence test DECTST CSI 4; Ps1; ... Psn y

Ps	=	test to run.
0	=	all tests.
1	=	power-up self-test.
2	=	RS-232 port data loopback.
3	=	printer port loopback.
6	=	RS-232 modem control line loopback.
7	=	DEC-423 port loopback.
9	=	repeat tests.

* Available in VT420 mode only.

Soft Terminal Reset (DECSTR) States

Mode	Mnemonic	State After DECSTR
Text cursor enable	DECTCEM	Cursor enabled.
Insert/replace	IRM	Replace.
Origin	DECOM	Absolute (cursor origin at upper-left of screen).
Autowrap	DECAWM	No autowrap.
National replacement character set	DECNRCM	Multinational set.
Keyboard action	KAM	Unlocked.
Numeric keypad	DECNKM	Numeric characters.
Cursor keys	DECCKM	Normal (arrow keys).
Other Control Functions
Set top and bottom margins	DECSTBM	Top margin = 1. Bottom margin = page length.
All character sets	G0, G1, G2, G3, GL, GR	VT420 default settings. (DECSTR works only in VT400 mode.)
Select graphic rendition	SGR	Normal rendition.
Select character attribute	DECSCA	Normal (erasable by DECSEL and DECSED).
Save cursor state	DECSC	Home position with VT420 defaults.
Assign user-preferred supplemental set	DECAUPSS	Set selected in set-up.
Select active status display	DECSASD	Main display (first 24 lines).
Keyboard position mode.	DECKPM	Character codes.

14 Session Management

Enable Session Command

CSI & x

A. VT52 Mode Control Codes

Sequence	Action
ESC A	Cursor up.
ESC B	Cursor down.
ESC C	Cursor right.
ESC D	Cursor left.
ESC F	Enter graphics mode.
ESC G	Exit graphics mode.
ESC H	Move the cursor to the home position.
ESC I	Reverse line feed.
ESC J	Erase from the cursor to the end of the screen.
ESC K	Erase from the cursor to the end of the line.
ESC Y Pl Pc	Move cursor to line Pl and column Pc.
ESC Z	Identify. (host to terminal)
ESC / Z	Report. (terminal to host)
ESC =	Enter alternate keypad mode.
ESC >	Exit alternate keypad mode.
ESC <	Exit VT52 mode. (Enter VT100 mode.)
ESC ^	Enter autoprint mode.
ESC _	Exit autoprint mode.
ESC W	Enter printer controller mode.
ESC X	Exit printer controller mode.
ESC ]	Print the screen.
ESC V	Print the line with the cursor.

9VT420 Programming Summary

2 Character Encoding

Control Characters

C0 (7-Bit) Control Characters Recognized

C1 (8-Bit) Control Characters Recognized

8-Bit Control Characters and Their 7-Bit Equivalents

Using Macros

3 Keyboard Codes

Codes Sent by Editing Keys

Codes Sent by Arrow Keys

Codes Sent by Numeric Keypad Keys

Codes Sent by the Top-Row Function Keys

Keys Used to Send 7-Bit Control Characters

4 Emulating VT Series Terminals

Selecting an Operating Level (DECSCL)

Sending C1 Controls to the Host

Character Set Mode (DECNRCM)

5 Using Character Sets

Selecting Graphic Character Sets

Designating Character Sets (SCS Sequences)

Mapping Character Sets

Locking Shifts (LS)

Single Shifts (SS)

Assigning User-Preferred Supplemental Sets (DECAUPSS)

ANSI Conformance Levels

Soft Character Sets

Character Cell Sizes

Converting Binary Code to an ASCII Character

Downloading Soft Characters

DECDLD Parameter Characters

Valid DECDLD Parameter Combinations

Clearing a Soft Character Set

6 Page Memory

Setting the Page Format

Moving Through Page Memory

7 Visual Character and Line Attributes

Character and Line Attribute Sequences

Visual Character Attribute Values

8 Editing

Editing Sequences

9 Rectangular Area Operations

Rectangular Area Control Functions

10 Cursor Movement and Panning

Cursor Movement and Panning Sequences

11 Keyboard, Printing, and Display Commands

Keyboard Control Sequences

Programming UDKs

Printing Control Sequences

Screen Display Control Sequences

12 VT420 Reports

Sequences for VT420 Reports

13 Resetting and Testing the Terminal

Resetting and Testing Sequences

Soft Terminal Reset (DECSTR) States

14 Session Management

Enable Session Command

A. VT52 Mode Control Codes

9
VT420 Programming Summary