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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
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<DIV CLASS="navbar"><A HREF="http://vt100.net/"><IMG CLASS="button" SRC="vt100.net-logo.png" ALT="VT100.net" HEIGHT="16" WIDTH="102"></A> VT102 User Guide<TABLE WIDTH="100%">
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<TD ALIGN="LEFT"><A HREF="chapter4.html">Chapter 4</A></TD>
<TD ALIGN="CENTER"><A HREF="contents.html">Contents</A></TD>
<TD ALIGN="RIGHT"><A HREF="chapter6.html">Chapter 6</A></TD>
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<H1 ID="S5"><SPAN CLASS="chapnum">5</SPAN> Received Character Processing</H1>
<H2 ID="S5.1">General</H2>
<P>This chapter describes how the VT102 processes received characters.
There are two types of received characters, display characters and control
functions. The chapter covers all display characters and control functions
used by the terminal.</P>
<H2 ID="S5.2">Received Characters</H2>
<P>The terminal processes characters according to American National
Standards Institute (ANSI) standards X3.64-1979, X3.4-1977, and X3.41-1974.
ANSI standard X3.4 defines the American Standard Code for Information
Interchange (ASCII). <A HREF="table5-1.html">Table 5-1</A> shows each ASCII character with its
binary, octal, decimal, and hexadecimal values. ASCII corresponds to the
International Standards Organization (ISO) Standard 646 and International
Telegraph and Telephone Consultative Committee (CCITT) Alphabet
5.</P>
<P>The terminal processes a received character based on character types
defined by ANSI. Position in the ASCII table tells you whether a character
is a control function or display character. The ASCII table is 8 columns
wide and 16 rows long. The control functions are in columns 0 and 1. The
display characters are in columns 2 through 7. However, the terminal
uses space (SP) as either an information separator control function or
display character. Delete (DEL) is always a control function.</P>
<H2 ID="S5.3">Display Characters</H2>
<P>Display characters are received characters displayed on the screen. The
actual character displayed depends on the character set selected. You
select the character set by using control functions. See <A HREF="#S5.5.2.16">Character Sets
and Selection</A> in this chapter for more information.</P>
<H2 ID="S5.4">Control Characters</H2>
<P>These single-character control functions start, modify, or stop terminal
operations; the control functions are not displayed. <A HREF="table5-2.html">Table 5-2</A> defines the
control characters recognized by the terminal. All other control characters
are ignored.</P>
<P>Each control character in this chapter has a mnemonic, listed in <A HREF="table5-2.html">Table 5-2</A>.
The mnemonic is an abbreviation of the control character name.</P>
<H2 ID="S5.5">Escape and Control Sequences</H2>
<P>Escape and control sequences provide additional control functions not
provided by the single-character controls of the character set. These multiple-character
sequences are not displayed; instead, they control terminal
operation. Escape and control sequences are defined by ANSI X3.41-1977
and X3.64-1979. See <A HREF="appendixd.html">Appendix D</A> for more information about sequences
and sequence formats.</P>
<P>The terminal provides upward and downward software compatibility. It can
respond to control functions created to meet private DIGITAL standards
and present ANSI standards. Therefore, you can use existing software designed
for previous terminals (such as the VT52), or new software designed
for ANSI standards. However, future video terminals may not accept
private DIGITAL sequences. Therefore, all new software should use
ANSI-compatible sequences.</P>
<P>The terminal uses VT52 mode to respond to private DIGITAL sequences
like a VT52 terminal.</P>
<P>The terminal uses ANSI mode to respond to a subset of control functions
specified by ANSI. All control functions not presently specified by ANSI
are created to comply with the extensions permitted by ANSI standards.
These sequences are considered ANSI private sequences.</P>
<P>The ANSI-compatible control functions in this user guide have a mnemonic
assigned by ANSI. If the control function is an ANSI private control function
(defined by DIGITAL), the mnemonic begins with DEC. The escape
and control sequences shown here use ASCII characters. You must type
the characters in the sequences exactly as shown (upper or lowercase).
The text provides the octal equivalent of each character in the sequence
as a second reference. See <A HREF="table5-1.html">Table 5-1</A> for decimal and hexadecimal representations.</P>
<P>The following section groups sequences by software compatibility (ANSI
or VT52) and function (<A HREF="table5-3.html">Table 5-3</A>). <A HREF="appendixc.html">Appendix C</A> summarizes all control
functions.</P>
<H3 ID="S5.5.1">Error Recovery</H3>
<P>Current standards do not specify the action performed when the terminal
receives a control function with an error. Errors are incorrect parameters,
invalid control functions, or control characters embedded in control function
sequences. The terminal usually recovers from these errors by performing
as much of the function as possible. The specific error recovery
procedures are as follows.</P>
<UL>
<LI>Unrecognized control functions are usually ignored.</LI>
<LI>Unsupported control functions (valid control functions not listed in
this user guide) are usually ignored, but may produce unexpected results.</LI>
<LI>If a control character is received within a sequence, the terminal performs
the function of the control character, followed by the function
of the sequence.</LI>
<LI>If cancel (CAN, octal 030) or substitute (SUB, octal 032) is received
during a sequence, the current sequence is aborted. The terminal
displays the substitute character, followed by characters in the sequence
received after CAN or SUB.</LI>
</UL>
<H3 ID="S5.5.2">ANSI-Compatible Sequences</H3>
<P>ANSI-compatible sequences meet ANSI standards X3.64-1979 and X3.41-1974.
This section describes the ANSI control functions used by the terminal.
You can select ANSI compatibility from the keyboard in SET-UP
(<A HREF="chapter3.html">Chapter 3</A>) or have the computer use a sequence. (See <A HREF="#S5.5.3">VT52-Compatible
Sequences</A> in this chapter).</P>
<H4 ID="S5.5.2.1">SET-UP Feature and Mode Selection</H4>
<P>SET-UP features change how the
terminal operates. You can select these features from the keyboard in
SET-UP. The computer can select some SET-UP features by using control
functions. However, features selected by the computer are stored in operating
memory. The computer cannot store feature selections in user memory.
(See <A HREF="chapter3.html">Chapter 3</A> for more information about SET-UP feature memories).</P>
<P>Some SET-UP features are modes. A mode affects terminal operation.
The terminal uses the selected mode until you or the computer change
the selection. <A HREF="table5-4.html">Table 5-4</A> lists SET-UP features and modes. The computer
changes modes by using set mode (SM) and reset mode (RM) sequences.
Set and reset the terminal modes by using the following sequences.</P>
<P CLASS="note">NOTE: Ps represents a variable parameter selected from a list of parameters.
A series of asterisks (***) represent the parameter in the octal sequence.
The parameter is transmitted using ASCII characters. When you
set several modes with a single SM or RM sequence, a semicolon (;, octal
073) separates parameters.</P>
<P><STRONG>Set Mode</STRONG></P>
<PRE CLASS="code">ESC [ Ps ; ... ; Ps h
033 133 *** 073 073 *** 150</PRE>
<P>Sets one or more modes specified by selective parameters (Ps) in the parameter
string.</P>
<P><STRONG>Reset Mode (RM)</STRONG></P>
<PRE CLASS="code">ESC [ Ps ; ... ; Ps l
033 133 *** 073 073 *** 154</PRE>
<P>Resets one or more modes specified by selective parameters (Ps) in the
parameter string.</P>
<P><A HREF="table5-5.html">Table 5-5</A> lists the ANSI-specified modes and their selective parameters
(Ps). <A HREF="table5-6.html">Table 5-6</A> lists the ANSI-compatible private modes and their selective
parameters. When you change ANSI-compatible private modes, the
first character in the parameter string is a question mark (?, octal 077). All
parameters in the sequence are interpreted as ANSI compatible private
parameters. This chapter explains each mode in detail and provides the
sequences to set and reset each mode.</P>
<P>The following example shows the use of the question mark (used with
ANSI private parameters) and semicolon (used with multiple parameters).
The sequence sets both column and scroll modes.</P>
<PRE CLASS="code">ESC [ ? 3 ; 4 h
033 133 077 063 073 064 150</PRE>
<P><A HREF="table5-7.html">Table 5-7</A> describes modes specified in ANSI X3.64-1979 that are permanently
set, permanently reset, or not applicable. See the ANSI standard
for more information about these modes.</P>
<H4 ID="S5.5.2.2">ANSI/VT52 Compatibility</H4>
<P>The terminal is compatible with both ANSI
and private DIGITAL standards. Therefore, you can use new software that
meets both ANSI standards, and existing software designed for previous
terminals (such as the VT52).</P>
<P>ANSI-compatible sequences meet ANSI standards X3.64-1979 and X3.41-1974.
You select ANSI compatibility by using the ANSI/VT52 mode (DECANM)
sequence in VT52 mode. See <A HREF="#S5.5.3">VT52-Compatible Sequences</A> in this
chapter for details on selecting ANSI sequence compatibility. In ANSI
mode, the following sequence selects compatibility with private DIGITAL
sequences (VT52 mode).</P>
<P>Features and modes selected in ANSI mode are also used in VT52 mode.
However, these features and modes usually cannot change in VT52
mode.</P>
<P><STRONG>VT52 Mode (DECANM)</STRONG></P>
<PRE CLASS="code">ESC [ ? 2 l
033 133 077 062 154</PRE>
<P>In ANSI mode, reset selects private DIGITAL sequence compatibility. In
VT52 mode, the terminal responds like a VT52 to private DIGITAL sequences.</P>
<H4 ID="S5.5.2.3">Scrolling</H4>
<P>Scrolling is the upward or downward movement of existing
lines on the screen. This makes room for more display lines at either the
top or bottom of the scrolling region. There are two methods of scrolling,
jump scroll and smooth scroll. Select the type of scrolling by using the
following sequences.</P>
<P CLASS="note">NOTE: In full-duplex communication, the auto XON/XOFF SET-UP feature
prevents the loss of received characters when using smooth scroll. If
auto XON/XOFF is not used, fill characters are needed.</P>
<P><STRONG>Scroll Mode (DECSCLM)</STRONG></P>
<PRE CLASS="code">ESC [ ? 4 h
033 133 077 064 150</PRE>
<P>Set selects smooth scroll. Smooth scroll lets the terminal add 6 lines per
second to screen (power feature = 60 Hz), or 5 lines per second (power
feature = 50 Hz).</P>
<PRE CLASS="code">ESC [ ? 4 l
033 133 077 064 154</PRE>
<P>Reset selects jump scroll. Jump scroll lets the terminal add lines to the
screen as fast as possible.</P>
<H4 ID="S5.5.2.4">Scrolling Region</H4>
<P>This region is the area of the screen between the top
and bottom margins. The margins determine which screen lines move during
scrolling. Characters added outside the scrolling region do not cause
the screen to scroll. The minimum size of the scrolling region is two lines.
Therefore, the line number of the top margin must be less than the number
of the bottom margin. The origin mode selects line numbers.</P>
<P>After the margins are selected, the cursor moves to the home position.
The origin mode feature also selects the home position. Select the top
and bottom margins of the scrolling region by using the following sequence.</P>
<P CLASS="note">NOTES: When you power up or use the Reset command, the scrolling
region becomes the full screen.</P>
<P CLASS="note">Pt and Pb represent variable numeric parameters. The parameters are
decimal numbers transmitted to the terminal as ASCII characters. Asterisks
(***) represent one or more variable numeric parameters in the octal
sequence.</P>
<P><STRONG>Set Top and Bottom Margins (DECSTBM)</STRONG></P>
<PRE CLASS="code">ESC [ Pt ; Pb r
033 133 *** 073 *** 162</PRE>
<P>Selects top and bottom margins, defining the scrolling region. Pt is line
number of first line in the scrolling region. Pb is line number of bottom line.
If Pt and Pb are not selected, the complete screen is used (no margins).</P>
<H4 ID="S5.5.2.5">Origin</H4>
<P>This mode determines if the cursor can move outside the scrolling
region (the area between the top and bottom margins). You can move
the cursor outside the margins with the cursor position (CUP) and horizontal
and vertical position (HVP) sequences.</P>
<P>Lines on the screen are numbered according to the location of the home
position. Home position is always line 1, column 1. The cursor moves to
the new home position whenever origin mode is selected. Select origin
mode by using the following sequences.</P>
<P CLASS="note">NOTE: When you power up or use the Reset command, origin mode resets.</P>
<P><STRONG>Origin Mode (DECOM)</STRONG></P>
<PRE CLASS="code">ESC [ ? 6 h
033 133 077 066 150</PRE>
<P>Set selects home position in scrolling region. Line numbers start at top
margin of scrolling region. The cursor cannot move out of scrolling region.</P>
<PRE CLASS="code">ESC [ ? 6 l
033 133 077 066 154</PRE>
<P>Reset selects home position in upper-left corner of screen. Line numbers
are independent of the scrolling region (absolute). Use CUP and HVP sequences
to move cursor out of scrolling region.</P>
<H4 ID="S5.5.2.6">Cursor Positioning</H4>
<P>The cursor indicates the active screen position
where the next character will appear. The cursor moves:</P>
<UL>
<LI>One column to the right when a character appears</LI>
<LI>One line down after a linefeed (LF, octal 012), form feed (FF, octal
014) or vertical tab (VT, octal 013) (Linefeed/new line may also
move the cursor to the left margin)</LI>
<LI>To the left margin after a carriage return (CR, octal 015)</LI>
<LI>One column to the left after a backspace (BS, octal 010)</LI>
<LI>To the next tab stop (or right margin if no tabs are set) after a horizontal
tab character (HT, octal 011)</LI>
<LI>To the home position when the top and bottom margins of the scrolling
region (DECSTBM) or origin mode (DECOM) selection changes.</LI>
</UL>
<P>You can also move the cursor by using the following sequences.</P>
<P CLASS="note">NOTE: Pn represents a variable numeric parameter. The parameter is a
decimal number transmitted to the terminal by using ASCII characters. If
you select no parameter or 0, the terminal assumes the parameter equals
1. Asterisks (***) represent one or more characters in the octal sequence.</P>
<P><STRONG>Cursor Up (CUU)</STRONG></P>
<PRE CLASS="code">ESC [ Pn A
033 133 *** 101</PRE>
<P>Moves cursor up Pn lines in same column. Cursor stops at top margin.</P>
<P><STRONG>Cursor Down (CUD)</STRONG></P>
<PRE CLASS="code">ESC [ Pn B
033 133 *** 102</PRE>
<P>Moves cursor down Pn lines in same column. Cursor stops at bottom
margin.</P>
<P><STRONG>Cursor Forward (CUF)</STRONG></P>
<PRE CLASS="code">ESC [ Pn C
033 133 *** 103</PRE>
<P>Moves cursor right Pn columns. Cursor stops at right margin.</P>
<P><STRONG>Cursor Backward (CUB)</STRONG></P>
<PRE CLASS="code">ESC [ Pn D
033 133 *** 104</PRE>
<P>Moves cursor left Pn columns. Cursor stops at left margin.</P>
<P CLASS="note">NOTE: Pl and Pc represent variable numeric parameters. The parameter
is a decimal number that represents one or more characters transmitted
to the terminal as ASCII characters. Asterisks (***) represent the variable
parameter in the octal sequence.</P>
<P><STRONG>Cursor Position (CUP)</STRONG></P>
<PRE CLASS="code">ESC [ Pl ; Pc H
033 133 *** 073 *** 110</PRE>
<P>Moves cursor to line Pl, column Pc. If Pl or Pc are not selected or selected
as 0, the cursor moves to first line or column, respectively. Origin mode
(DECOM) selects line numbering and ability to move cursor into margins.</P>
<P CLASS="note">NOTE: CUP operates the same as the horizontal and vertical position
(HVP) sequence.</P>
<P><STRONG>Cursor Position (Home) (CUP)</STRONG></P>
<PRE CLASS="code">ESC [ H
033 133 110</PRE>
<P>Moves cursor to home position, selected by origin mode (DECOM).</P>
<P><STRONG>Horizontal and Vertical Position (HVP)</STRONG></P>
<PRE CLASS="code">ESC [ Pl ; Pc f
033 133 *** 073 *** 146</PRE>
<P>Moves cursor to line Pl, column Pc. If Pl or Pc are not selected or selected
as 0, the cursor moves to first line or column, respectively. Origin mode
(DECOM) selects line numbering and ability to move the cursor into
margins.</P>
<P CLASS="note">NOTE: HVP operates the same as the cursor position (CUP) sequence.</P>
<P><STRONG>Horizontal and Vertical Position (Home) (HVP)</STRONG></P>
<PRE CLASS="code">ESC [ f
033 133 146</PRE>
<P>Cursor moves to home position selected by origin mode (DECOM).</P>
<P><STRONG>Index (IND)</STRONG></P>
<PRE CLASS="code">ESC D
033 104</PRE>
<P>Moves cursor down one line in same column. If cursor is at bottom margin,
screen performs a scroll-up.</P>
<P><STRONG>Reverse Index (RI)</STRONG></P>
<PRE CLASS="code">ESC M
033 115</PRE>
<P>Moves cursor up one line in same column. If cursor is at top margin,
screen performs a scroll-down.</P>
<P><STRONG>Next Line (NEL)</STRONG></P>
<PRE CLASS="code">ESC E
033 105</PRE>
<P>Moves cursor to first position on next line. If cursor is at bottom margin,
screen performs a scroll-up.</P>
<P><STRONG>Save Cursor (DECSC)</STRONG></P>
<PRE CLASS="code">ESC 7
033 067</PRE>
<P>Saves cursor position, character attribute (graphic rendition), character
set, and origin mode selection. (See restore cursor).</P>
<P><STRONG>Restore Cursor (DECRC)</STRONG></P>
<PRE CLASS="code">ESC 8
033 070</PRE>
<P>Restores previously saved cursor position, character attribute (graphic
rendition), character set, and origin mode selection. If none were saved,
the cursor moves to home position.</P>
<H4 ID="S5.5.2.7">Columns Per Line</H4>
<P>This mode selects the number of columns in a display
line, 80 or 132. With either selection, the screen can display 24 lines.
Select the number of columns per line by using the following sequences.</P>
<P CLASS="note">NOTE: When you change the number of columns per line, the screen is
erased. This also sets the scrolling region for full screen (24 lines).</P>
<P><STRONG>Column Mode (DECCOLM)</STRONG></P>
<PRE CLASS="code">ESC [ ? 3 h
033 133 077 063 150</PRE>
<P>Set selects 132 columns per line.</P>
<PRE CLASS="code">ESC [ ? 3 l
033 133 077 063 154</PRE>
<P>Reset selects 80 columns per line.</P>
<H4 ID="S5.5.2.8">Auto Wrap</H4>
<P>This mode selects where a received character will appear
when the cursor is at the right margin. Select auto wrap by using the following
sequences.</P>
<P CLASS="note">NOTE: Regardless of the auto wrap SET-UP feature selection, the tab
character never moves the cursor to the next line.</P>
<P><STRONG>Auto Wrap Mode (DECAWM)</STRONG></P>
<PRE CLASS="code">ESC [ ? 7 h
033 133 077 067 150</PRE>
<P>Set selects auto wrap. Any display characters received when cursor is at
right margin appear on next line. The display scrolls up if cursor is at end
of scrolling region.</P>
<PRE CLASS="code">ESC [ ? 7 l
033 133 077 067 154</PRE>
<P>Reset turns auto wrap off. Display characters received when cursor is at
right margin replace previously displayed character.</P>
<H4 ID="S5.5.2.9">Screen Background</H4>
<P>This mode selects either light (reverse) or dark
display background on the screen. Select screen mode by using the following
sequences.</P>
<P><STRONG>Screen Mode (DECSCNM)</STRONG></P>
<PRE CLASS="code">ESC [ ? 5 h
033 133 077 065 150</PRE>
<P>Set selects reverse screen, a white screen background with black characters.</P>
<PRE CLASS="code">ESC [ ? 5 l
033 133 077 065 154</PRE>
<P>Reset selects normal screen, a black screen background with white characters.</P>
<H4 ID="S5.5.2.10">Linefeed/New Line</H4>
<P>This mode selects the control character(s) transmitted
by <SPAN CLASS="keyname">RETURN</SPAN>. Linefeed/new line also selects the action taken by the
terminal when receiving linefeed, form feed, and vertical tab. <A HREF="table5-8.html">Table 5-8</A>
provides a summary of the feature. Select linefeed/new line mode by using
the following sequences.</P>
<P><STRONG>Linefeed/New Line Mode (LNM)</STRONG></P>
<PRE CLASS="code">ESC [ 2 0 h
033 133 062 060 150</PRE>
<P>Set causes a received linefeed, form feed, or vertical tab to move cursor
to first column of next line. <SPAN CLASS="keyname">RETURN</SPAN> transmits both a carriage return and
linefeed. This selection is also called new line option.</P>
<PRE CLASS="code">ESC [ 2 0 l
033 133 062 060 154</PRE>
<P>Reset causes a received linefeed, form feed, or vertical tab to move cursor
to next line in current column. <SPAN CLASS="keyname">RETURN</SPAN> transmits a carriage return.</P>
<H4 ID="S5.5.2.11">Keyboard Action (FDX)</H4>
<P>This mode is only used during full-duplex, not
half-duplex communication. Keyboard action lets the computer turn the
keyboard on or off. This mode always resets when you enter SET-UP. Select
keyboard action mode by using the following sequences.</P>
<P><STRONG>Keyboard Action Mode (KAM)</STRONG></P>
<PRE CLASS="code">ESC [ 2 h
033 133 062 150</PRE>
<P>Set turns off keyboard and turns on KBD LOCKED.</P>
<PRE CLASS="code">ESC [ 2 l
033 133 062 154</PRE>
<P>Reset turns on keyboard and turns off KBD LOCKED.</P>
<H4 ID="S5.5.2.12">Auto Repeat</H4>
<P>This mode selects automatic key repeating. A key
pressed for more than one-half second automatically repeats the transmission
of the character. Key repeating does not affect <SPAN CLASS="keyname">SET-UP</SPAN>, <SPAN CLASS="keyname">ESC</SPAN>, <SPAN CLASS="keyname">RETURN</SPAN>,
<SPAN CLASS="keyname">ENTER</SPAN>, <SPAN CLASS="keyname">NO SCROLL</SPAN>, and <SPAN CLASS="keyname">CTRL</SPAN>. Select auto repeat mode by using
the following sequences.</P>
<P><STRONG>Auto Repeat Mode (DECARM)</STRONG></P>
<PRE CLASS="code">ESC [ ? 8 h
033 133 077 070 150</PRE>
<P>Set selects auto repeat. A key pressed for more than one-half second
automatically repeats.</P>
<PRE CLASS="code">ESC [ ? 8 l
033 133 077 070 154</PRE>
<P>Reset turns off auto repeat. Keys do not automatically repeat.</P>
<H4 ID="S5.5.2.13">Local Echo (Keyboard Send-Receive)</H4>
<P>This mode selects local echo,
which causes every character transmitted by the terminal to automatically
appear on the screen. Therefore, the computer does not have to transmit
(echo) the character back to the terminal for display. When local echo is
off, the terminal only transmits characters to the computer. The computer
must echo the characters back to the terminal for display. Select send-receive
mode by using the following sequences.</P>
<P><STRONG>Send-Receive Mode (SRM)</STRONG></P>
<PRE CLASS="code">ESC [ 1 2 h
033 133 061 062 150</PRE>
<P>Set turns off local echo. The terminal transmits characters to the computer,
which must echo characters for display on screen.</P>
<PRE CLASS="code">ESC [ 1 2 l
033 133 061 062 154</PRE>
<P>Reset selects local echo. Characters transmitted to the computer automatically
appear on the screen.</P>
<H4 ID="S5.5.2.14">Cursor Key Character Selection</H4>
<P>In application keypad mode
(DECKPAM), cursor key mode selects the set of characters transmitted
by the cursor keys. In numeric keypad mode (DECKPNM), cursor key
mode resets and cannot change. See <A HREF="table5-9.html">Table 5-9</A> for the codes transmitted
by the cursor keys. Select cursor key mode by using the following sequences.</P>
<P CLASS="note">NOTE: When you power up or use a Reset command, cursor key mode
resets. This mode also resets during a communication line connection in
all communication except full-duplex no modem control (FDX A). See
<A HREF="chapter6.html">Chapter 6</A> for more information about communication.</P>
<P><STRONG>Cursor Key Mode (DECCKM)</STRONG></P>
<PRE CLASS="code">ESC [ ? 1 h
033 133 077 061 150</PRE>
<P>Set selects cursor keys to generate control (application) functions.</P>
<PRE CLASS="code">ESC [ ? 1 l
033 133 077 061 154</PRE>
<P>Reset selects cursor keys to generate ANSI cursor control sequences.</P>
<H4 ID="S5.5.2.15">Keypad Character Selection</H4>
<P>The numeric keypad generates either numeric
characters or control functions. Selecting application or numeric
keypad mode determines the type of characters. The keypad mode also
affects the cursor keys. See <A HREF="#S5.5.2.14">Cursor Key Character Selection</A> in this chapter
for more information. The program function (PF) keys generate the
same characters regardless of the keypad character selection. See <A HREF="table5-10.html">Table
5-10</A> for the characters generated by the keypad. Select the keypad mode
by using the following sequences.</P>
<P CLASS="note">NOTE: When you power up or use a Reset command, the terminal selects
numeric keypad mode. This mode is also selected during communication
line connections, except full-duplex no modem control (FDX A).
See <A HREF="chapter6.html">Chapter 6</A> for more information about communication line connections.</P>
<P><STRONG>Application Keypad Mode (DECKPAM)</STRONG></P>
<PRE CLASS="code">ESC =
033 075</PRE>
<P>Selects application keypad mode. Keypad generates control functions.
Cursor key mode (DECCKM) selects type of characters generated by cursor
keys.</P>
<P><STRONG>Numeric Keypad Mode (DECKPNM)</STRONG></P>
<PRE CLASS="code">ESC >
033 076</PRE>
<P>Selects numeric keypad mode. Keypad generates characters that match
the numeric, comma, period, and minus sign keys on main keyboard. Cursor
keys generate ANSI cursor control sequences.</P>
<H4 ID="S5.5.2.16">Character Sets and Selection</H4>
<P>The terminal can display up to 254 different
characters; however, the terminal only holds 127 display characters
in basic read only memory (ROM). You must install an alternate character
set ROM for the remaining 127 display characters.</P>
<P>The terminal can select only 94 characters (one character set) at a time.
Therefore, the terminal uses the following five character sets, with some
characters appearing in more than one set.</P>
<UL>
<LI>United States</LI>
<LI>United Kingdom</LI>
<LI>Special characters and line drawing (VT100 compatible)</LI>
<LI>Alternate ROM</LI>
<LI>Alternate ROM special characters</LI>
</UL>
<P>Tables <A HREF="table5-11.html">5.11</A>, <A HREF="table5-12.html">5.12</A> and <A HREF="table5-13.html">5.13</A> show the character sets. The United States and
United Kingdom character sets meet the standard of the "ISO international register of character sets to be used with escape sequences".
The space (SP) and control characters are the same in all sets.</P>
<P>The terminal uses two active character sets at any one time. The computer
designates these sets as G0 and G1, using the select character set
(SCS) sequence. Then a single control character can switch between
sets. Shift In (SI, octal 017) invokes the G0 character set; shift out (SO,
octal 016) invokes the G1 character set.</P>
<P>The designated character sets are active until the terminal receives another
SCS sequence. You can use the SCS sequence as often as needed
to designate G0 and G1. Designate G0 by using the following sequences.</P>
<P CLASS="note">NOTE: The terminal uses the character set selected in SET-UP after all
communication line connections, except full-duplex no modem control
(FDX A). See <A HREF="chapter6.html">Chapter 6</A> for more information about communication line
connections.</P>
<P><STRONG>Select Character Set (SCS)</STRONG></P>
<PRE CLASS="code">ESC ( A
033 050 101</PRE>
<P>Designates the UK character set as G0.</P>
<PRE CLASS="code">ESC ( B
033 050 102</PRE>
<P>Designates the US character set as G0.</P>
<PRE CLASS="code">ESC ( 0
033 050 060</PRE>
<P>Designates the special characters and line drawing character set as G0.</P>
<PRE CLASS="code">ESC ( 1
033 050 061</PRE>
<P>Designates the alternate ROM character set as G0.</P>
<PRE CLASS="code">ESC ( 2
033 050 062</PRE>
<P>Designates the alternate ROM special characters character set as G0.</P>
<P>Designate G1 by using the following sequences.</P>
<P><STRONG>Select Character Set (SCS)</STRONG></P>
<PRE CLASS="code">ESC ) A
033 051 101</PRE>
<P>Designates the UK character set as G1.</P>
<PRE CLASS="code">ESC ) B
033 051 102</PRE>
<P>Designates the US character set as G1.</P>
<PRE CLASS="code">ESC ) 0
033 051 060</PRE>
<P>Designates the special characters and line drawing character set as G1.</P>
<PRE CLASS="code">ESC ) 1
033 051 061</PRE>
<P>Designates the alternate ROM character set as G1.</P>
<PRE CLASS="code">ESC ) 2
033 051 062</PRE>
<P>Designates the alternate ROM special characters character set as G1.</P>
<P>The terminal also has G2 and G3 character sets. However, these are always
the default (selected in SET-UP) character sets. You select G2 and
G3 for only one character at a time. The terminal returns to the previous
character set after displaying a single character. Select G2 and G3 for
one character by using the following sequences.</P>
<P><STRONG>Single Shift 2 (SS2)</STRONG></P>
<PRE CLASS="code">ESC N
033 116</PRE>
<P>Selects G2 (default) character set for one character. You select G2 in SET-UP.</P>
<P><STRONG>Single Shift 3 (SS3)</STRONG></P>
<PRE CLASS="code">ESC O
033 117</PRE>
<P>Selects G3 (default) character set for one character. You select G3 in SET-UP.</P>
<P>The terminal can transmit characters displayed on the screen to the optional
serial printer. When transmitting characters to the printer, the terminal
attempts to select the correct character set. If the printer does not
support multiple character sets, using multiple character sets causes unexpected
characters to print. Remember the following rules when the terminal
transmits characters from more than one character set.</P>
<UL>
<LI>When starting a print operation, make sure the G0 character sets in
the terminal and printer are the same.</LI>
<LI>During printing, the terminal checks that the next character to transmit
belongs to the presently selected G0 character set. If not, the terminal
transmits a G0 designator to the printer to select the correct
character set. The G1 designator is never used.</LI>
<LI>At the end of printing, the terminal checks that the printer's G0 character
set is the same as when printing started. If not, the terminal
transmits a G0 designator to the printer to select the original G0
character set. The designator is transmitted before the print termination
character.</LI>
</UL>
<P>Before transmitting characters to the printer, the terminal must determine
the character set selected. If the character is not in the currently selected
G0 character set, the character sets are searched as follows.</P>
<OL>
<LI>US/UK (selected in SET-UP)</LI>
<LI>US/UK (not selected in SET-UP)</LI>
<LI>Special characters and line drawing</LI>
<LI>Alternate ROM</LI>
<LI>Alternate ROM special characters</LI>
</OL>
<P CLASS="note">NOTE: The substitute character appears on the screen when the terminal
receives a parity error, the SUB or CAN control characters, and the <IMG SRC="char141.png" ALT="checker" HEIGHT="20" WIDTH="12">
(octal 141) character in the special character and line drawing character
set. The terminal always transmits the substitute character to the printer
as the SUB (octal 032) character.</P>
<H4 ID="S5.5.2.17">Character Attributes</H4>
<P>The terminal can display the following character
attributes that change the character display without changing the character.</P>
<UL>
<LI>Underline</LI>
<LI>Reverse video (character background opposite of the screen background
feature)</LI>
<LI>Blink</LI>
<LI>Bold (increased intensity)</LI>
<LI>Any combination of these attributes</LI>
</UL>
<P>You can select one or more character attributes at one time. Selecting an
attribute does not turn off other attributes already selected. After you select
an attribute, all characters received by the terminal appear with that
attribute. If you move the characters by scrolling, the attribute moves with
the characters. Select the character attributes by using the following sequences.</P>
<P><STRONG>Select Graphic Rendition (SGR)</STRONG></P>
<PRE CLASS="code">ESC [ m or ESC [ 0 m
033 133 155 033 133 060 155</PRE>
<P>Turns off character attributes.</P>
<PRE CLASS="code">ESC [ 1 m
033 133 061 155</PRE>
<P>Selects bold (increased intensity).</P>
<PRE CLASS="code">ESC [ 4 m
033 133 064 155</PRE>
<P>Selects underline.</P>
<PRE CLASS="code">ESC [ 5 m
033 133 065 155</PRE>
<P>Selects blink.</P>
<PRE CLASS="code">ESC [ 7 m
033 133 067 155</PRE>
<P>Selects reverse video.</P>
<H4 ID="S5.5.2.18">Tab Stops</H4>
<P>You select tab stop positions on the horizontal lines of the
screen. The cursor advances (tabs) to the next tab stop when the terminal
receives a horizontal tab (HT, octal 011). If no tab stops are set, horizontal
tab moves the cursor to the right margin. Set and clear the tab stops by
using the following sequences.</P>
<P><STRONG>Horizontal Tabulation Set (HTS)</STRONG></P>
<PRE CLASS="code">ESC H
033 110</PRE>
<P>Sets a horizontal tab stop at cursor position.</P>
<P><STRONG>Tabulation Clear (TBC)</STRONG></P>
<PRE CLASS="code">ESC [ g or ESC [ 0 g
033 133 147 033 133 060 147</PRE>
<P>Clears a horizontal tab stop at cursor position.</P>
<PRE CLASS="code">ESC [ 3 g
033 133 063 147</PRE>
<P>Clears all horizontal tab stops.</P>
<H4 ID="S5.5.2.19">Line Attributes</H4>
<P>These are display features that affect a complete display
line. The cursor selects the line affected by the attribute. The cursor
stays in the same character position when the attribute changes. However,
if the attribute would move the cursor past the right margin, the cursor
stops at the right margin. When you move lines on the screen by
scrolling, the attribute moves with the line. Select line attributes by using
the following sequences.</P>
<P CLASS="note">NOTE: If you erase an entire line by using the erase in display (ED) sequence,
the line attribute changes to single-height and single-width.</P>
<P><STRONG>Double-Height Line (DECDHL)</STRONG></P>
<PRE CLASS="code">Top Half: Bottom Half:
ESC # 3 ESC # 4
033 043 063 033 043 064</PRE>
<P>Makes the line with the cursor the top or bottom half of a double-height,
double-width line. Sequences work in pairs on adjacent lines. The same
character must be used on both lines to form full characters. If the line
was single-width, single-height, all characters to the right of center are
lost.</P>
<P><STRONG>Single-Width Line (DECSWL)</STRONG></P>
<PRE CLASS="code">ESC # 5
033 043 065</PRE>
<P>Makes the line with the cursor single-width, single-height. This is line attribute
for all new lines on screen.</P>
<P><STRONG>Double-Width Line (DECDWL)</STRONG></P>
<PRE CLASS="code">ESC # 6
033 043 066</PRE>
<P>Makes the line with the cursor double-width, single-height. If the line was
single-width, single-height, all characters to the right of center screen are
lost.</P>
<H4 ID="S5.5.2.20">Erasing</H4>
<P>Erasing removes characters from the screen without affecting
other characters on the screen. Erased characters are lost. The cursor
position does not change when erasing characters or lines.</P>
<P>If you erase a line by using the erase in display (ED) sequence, the line
attribute becomes single-height, single-width. If you erase a line by using
the erase in line (EL) sequence, the line attribute is not affected.</P>
<P>Erasing a character also erases any character attribute of the character.
Erase characters by using the following sequences.</P>
<P><STRONG>Erase In Line (EL)</STRONG></P>
<PRE CLASS="code">ESC [ K or ESC [ 0 K
033 133 113 033 133 060 113</PRE>
<P>Erases from cursor to end of line, including cursor position.</P>
<PRE CLASS="code">ESC [ 1 K
033 133 061 113</PRE>
<P>Erases from beginning of line to cursor, including cursor position.</P>
<PRE CLASS="code">ESC [ 2 K
033 133 062 113</PRE>
<P>Erases complete line.</P>
<P><STRONG>Erase In Display (ED)</STRONG></P>
<PRE CLASS="code">ESC [ J or ESC [ 0 J
033 133 112 033 133 060 112</PRE>
<P>Erases from cursor to end of screen, including cursor position.</P>
<PRE CLASS="code">ESC [ 1 J
033 133 061 112</PRE>
<P>Erases from beginning of screen to cursor, including cursor position.</P>
<PRE CLASS="code">ESC [ 2 J
033 133 062 112</PRE>
<P>Erases complete display. All lines are erased and changed to single-width.
Cursor does not move.</P>
<H4 ID="S5.5.2.21">Computer Editing</H4>
<P>Editing allows the computer to insert or delete characters
and lines of characters at the cursor position. The cursor position
does not change when inserting or deleting lines. Delete characters or insert
and delete lines by using the following sequences.</P>
<P CLASS="note">NOTE: Insertion-replacement mode (IRM) selects how characters are
added to the screen. See <A HREF="#S5.5.2.22">Inserting and Replacing Characters</A> in this
chapter for more information.</P>
<P><STRONG>Delete Character (DCH)</STRONG></P>
<PRE CLASS="code">ESC [ Pn P
033 133 *** 120</PRE>
<P>Deletes Pn characters, starting with the character at cursor position. When a
character is deleted, all characters to the right of cursor move left. This
creates a space character at right margin. This character has same character
attribute as the last character moved left.</P>
<P><STRONG>Insert Line (IL)</STRONG></P>
<PRE CLASS="code">ESC [ Pn L
033 133 *** 114</PRE>
<P>Inserts Pn lines at line with cursor. Lines displayed below cursor move
down. Lines moved past the bottom margin are lost. This sequence is ignored
when cursor is outside scrolling region.</P>
<P><STRONG>Delete Line (DL)</STRONG></P>
<PRE CLASS="code">ESC [ Pn M
033 133 *** 115</PRE>
<P>Deletes Pn lines, starting at line with cursor. As lines are deleted, lines
displayed below cursor move up. Lines added to bottom of screen have
spaces with same character attributes as last line moved up. This sequence
is ignored when cursor is outside scrolling region.</P>
<H4 ID="S5.5.2.22">Inserting and Replacing Characters</H4>
<P>The terminal displays received
characters at the cursor position. This mode determines how the terminal
adds characters to the screen. Insert mode displays the character and
moves previously displayed characters to the right. Replace mode adds
characters by replacing the character at the cursor position. Select
insertion-replacement mode by using the following sequences.</P>
<P CLASS="note">NOTE: This mode resets after a communication line connection in all
communication except full-duplex no modem control (FDX A). See <A HREF="chapter6.html">Chapter
6</A> for more information about communication line connections.</P>
<P><STRONG>Insertion-Replacement Mode (IRM)</STRONG></P>
<PRE CLASS="code">ESC [ 4 h
033 133 064 150</PRE>
<P>Set selects insert mode and turns INSERT on. New display characters
move old display characters to the right. Characters moved past the right
margin are lost.</P>
<PRE CLASS="code">ESC [ 4 l
033 133 064 154</PRE>
<P>Reset selects replace mode and turns INSERT off. New display characters
replace old display characters at cursor position. The old character
is erased.</P>
<H4 ID="S5.5.2.23">Printing</H4>
<P>The terminal has a serial printer interface for local printing. The
computer can select all print operations by using sequences. You can
only select two of the print operations from the keyboard, auto print and
print screen.</P>
<P>When you print characters from the screen, terminal and printer tab stops
are ignored. Print characters are spaced with the space (SP, octal 040)
character. The terminal transmits a carriage return (CR, octal 015) and
linefeed (LF, octal 012) after the last printable character of a line -- but not
a space character.</P>
<P>A line of double-height characters prints as two identical lines of single-width
characters. Double-width characters print as single-width characters
on a single line.</P>
<P>Before selecting a print operation, check the printer status by using the
printer status report (DSR) in ANSI mode. Do not select a print operation if
the serial printer is not ready to print. Select print operations by using the
following sequences.</P>
<P><STRONG>Media Copy (Auto Print On) (MC)</STRONG></P>
<PRE CLASS="code">ESC [ ? 5 i
033 133 077 065 151</PRE>
<P>Turns on auto print. A display line prints after you move cursor off the line,
using a linefeed, form feed, or vertical tab (also transmitted to printer).</P>
<P>The line also prints during an auto wrap. Auto wrap lines end with a
CR, LF.</P>
<P><STRONG>Media Copy (Auto Print Off) (MC)</STRONG></P>
<PRE CLASS="code">ESC [ ? 4 i
033 133 077 064 151</PRE>
<P>Turns off auto print.</P>
<P CLASS="note">NOTE: Printer controller has a higher priority than auto print. Therefore,
you can select printer controller and print characters during auto print.</P>
<P><STRONG>Media Copy (Printer Controller On) (MC)</STRONG></P>
<PRE CLASS="code">ESC [ 5 i
033 133 065 151</PRE>
<P>Turns on printer controller. The terminal transmits received characters to
printer without displaying them. The terminal does not insert or delete
spaces, provide line delimiters, or select the correct printer character set.</P>
<P><STRONG>Media Copy (Printer Controller Off) (MC)</STRONG></P>
<PRE CLASS="code">ESC [ 4 i
033 133 064 151</PRE>
<P>Turns off printer controller. Always move printhead to left margin before
turning off printer controller.</P>
<P><STRONG>Media Copy (Print Cursor Line) (MC)</STRONG></P>
<PRE CLASS="code">ESC [ ? 1 i
033 133 077 061 151</PRE>
<P>Prints display line with cursor. Cursor position does not change. Print cursor
line ends when line prints.</P>
<P><STRONG>Media Copy (Print Screen) (MC)</STRONG></P>
<PRE CLASS="code">ESC [ i or ESC [ 0 i
033 133 151 033 133 060 151</PRE>
<P>Prints the screen. Printer extent (DECEXT) selects full screen or scrolling
region to print. Select scrolling region by using the set top and bottom margins
(DECSTBM) sequence. Print screen ends when screen prints.</P>
<H4 ID="S5.5.2.24">Printer Extent</H4>
<P>This mode selects the full screen or the scrolling region
to print during a print screen. Select printer extent mode by using the following
sequences.</P>
<P><STRONG>Printer Extent Mode (DECPEX)</STRONG></P>
<PRE CLASS="code">ESC [ ? 1 9 h
033 133 077 061 071 150</PRE>
<P>Set selects the full screen to print during a print screen.</P>
<PRE CLASS="code">ESC [ ? 1 9 l
033 133 077 061 071 154</PRE>
<P>Reset selects the scrolling region to print during a print screen.</P>
<H4 ID="S5.5.2.25">Print Termination Character</H4>
<P>This mode determines if the terminal
should transmit a print termination character after a print screen. The form
feed (octal 014) control character serves as the print termination character.
Select printer form feed mode by using the following sequence.</P>
<P><STRONG>Printer Form Feed Mode (DECPFF)</STRONG></P>
<PRE CLASS="code">ESC [ ? 1 8 h
033 133 077 061 070 150</PRE>
<P>Set selects form feed as print termination character. The terminal transmits
this character to printer after each print screen.</P>
<PRE CLASS="code">ESC [ ? 1 8 l
033 133 077 061 070 154</PRE>
<P>Reset selects no termination character.</P>
<H4 ID="S5.5.2.26">Reports</H4>
<P>The terminal transmits reports in response to computer
requests. Reports determine terminal type and status, and cursor position.
The report requests and responses are as follows.</P>
<P CLASS="note">NOTE: The terminal does not respond to the DSR, DA, or DECID sequences
during printer controller operation.</P>
<P><STRONG>Device Status Report (DSR)</STRONG></P>
<PRE CLASS="code">ESC [ 5 n
033 133 065 156</PRE>
<P>Computer requests a status report (using a DSR sequence).</P>
<PRE CLASS="code">ESC [ 0 n
033 133 060 156</PRE>
<P>Terminal response: Ready, no malfunctions detected.</P>
<PRE CLASS="code">ESC [ 3 n
033 133 063 156</PRE>
<P>Terminal response: Malfunction, error in self-test. Reset and retry.</P>
<PRE CLASS="code">ESC [ ? 1 5 n
033 133 077 061 065 156</PRE>
<P>Computer requests a printer status report. Terminal checks status of
printer. This report should be requested before any printer operation.</P>
<PRE CLASS="code">ESC [ ? 1 3 n
033 133 077 061 063 156</PRE>
<P>Printer not connected to terminal. Data terminal ready (DTR) signal of the
printer has not been on since terminal turned on.</P>
<PRE CLASS="code">ESC [ ? 1 1 n
033 133 077 061 061 156</PRE>
<P>Printer not ready to print. Printer DTR was on, but is now off.</P>
<PRE CLASS="code">ESC [ ? 1 0 n
033 133 077 061 060 156</PRE>
<P>Printer ready to print. Printer DTR is on.</P>
<PRE CLASS="code">ESC [ 6 n
033 133 066 156</PRE>
<P>Computer requests a cursor position report from terminal.</P>
<P><STRONG>Cursor Position Report (CPR)</STRONG></P>
<PRE CLASS="code">ESC [ Pl ; Pc R
033 133 *** 073 *** 122</PRE>
<P>Terminal reports cursor position in response to DSR sequence request
from computer. Pl indicates line and Pc indicates column. No parameters,
or parameters of 0, indicate cursor is at home position. Origin mode (DECOM)
selects line numbering.</P>
<P><STRONG>Device Attributes (DA)</STRONG></P>
<PRE CLASS="code">ESC [ c or ESC [ 0 c
033 133 143 033 133 060 143</PRE>
<P>Computer requests terminal identify itself.</P>
<P><STRONG>Identify Terminal (DECID)</STRONG></P>
<PRE CLASS="code">ESC Z
033 132</PRE>
<P>Computer requests terminal to identify itself. Terminal uses device attributes
(DA) to respond. Future DIGITAL terminals may not support this sequence.
Therefore, new software should use device attributes.</P>
<P><STRONG>Device Attributes (DA)</STRONG></P>
<PRE CLASS="code">ESC [ ? 6 c
033 133 077 066 143</PRE>
<P>Terminal response: VT102.</P>
<H4 ID="S5.5.2.27">Reset</H4>
<P>Reset initializes the terminal and causes it to perform the internal
power-up self-test, erase the input buffer, and use the SET-UP selections
in user memory. Characters received during a reset are lost. To prevent
this, the computer may act in one of two ways.</P>
<OL>
<LI>(With auto XON/XOFF) Immediately after sending the reset sequence,
the computer should assume an XOFF from terminal. The
computer stops sending characters until it receives XON. The terminal
transmits XON only after it completes the reset.</LI>
<LI>(Without auto XON/XOFF) Use a delay of no less than 10 seconds
to allow the terminal to complete the function. This method, however,
does not guarantee against loss of characters when a reset error is
detected.</LI>
</OL>
<P>The terminal disconnects from the communication line during a reset. After
a reset, the terminal selects keypad numeric mode (DECKPNM) and
resets origin mode (DECOM). The terminal also selects the top and bottom
margins (scrolling region) for the full screen (DECSTBM). Reset the
terminal by using the following sequence.</P>
<P><STRONG>Reset to Initial State (RIS)</STRONG></P>
<PRE CLASS="code">ESC c
033 143</PRE>
<P>Resets the terminal to its initial state.</P>
<H4 ID="S5.5.2.28">Tests</H4>
<P>DECTST selects the self-tests used to verify terminal operation.
Self-tests provide error indications on the keyboard indicators or screen.
See <A HREF="chapter9.html">Chapter 9</A> for the meaning of the displayed errors. The terminal reports
the test results (pass or fail) to the computer by using a device status
report (DSR) sequence.</P>
<P>The terminal loses received characters while performing the test. To prevent
this, the computer may act in one of two ways.</P>
<OL>
<LI>(With auto XON/XOFF) Immediately after sending the invoke confidence
test sequence, the computer should assume an XOFF from
terminal. The computer stops sending characters until it receives
XON. The terminal transmits XON only after it completes the test.</LI>
<LI>(Without auto XON/XOFF) Use a delay of no less than 10 seconds
to allow the terminal to complete the test. This method, however,
does not guarantee against loss of characters when an error is detected.</LI>
</OL>
<P>Select terminal self-tests by using the following sequences.</P>
<P><STRONG>Invoke Confidence Test (DECTST)</STRONG></P>
<PRE CLASS="code">ESC [ 2 ; 1 y
033 133 062 073 061 171</PRE>
<P>Power-up test. Terminal resets and performs power-up test.</P>
<PRE CLASS="code">ESC [ 2 ; 2 y
033 133 062 073 062 171</PRE>
<P>Data loopback test. Uses test connector on modem interface connector.</P>
<PRE CLASS="code">ESC [ 2 ; 4 y
033 133 062 073 064 171</PRE>
<P>EIA loopback test. Uses test connector on modem interface connector.</P>
<PRE CLASS="code">ESC [ 2 ; 1 6 y
033 133 062 073 061 066 171</PRE>
<P>Printer loopback test. Uses test connector on printer interface connector.</P>
<PRE CLASS="code">ESC [ 2 ; 9 y
033 133 062 073 071 171</PRE>
<P>Repeats power-up test continuously until failure or power turned off.</P>
<PRE CLASS="code">ESC [ 2 ; 1 0 y
033 133 062 073 061 060 171</PRE>
<P>Repeats data loopback test continuously until failure or power turned off.
Uses test connector on the modem interface connnector.</P>
<PRE CLASS="code">ESC [ 2 ; 1 2 y
033 133 062 073 061 062 171</PRE>
<P>Repeats EIA loopback test continuously until failure or power turned off.
Uses test connector on modem interface connector.</P>
<PRE CLASS="code">ESC [ 2 ; 2 4 y
033 133 062 073 062 064 171</PRE>
<P>Repeats printer loopback test continuously until failure or power turned
off. Uses test connector on printer interface.</P>
<H4 ID="S5.5.2.29">Adjustments</H4>
<P>The terminal has a screen alignment pattern that lets
Field Service personnel adjust the screen. Display the screen alignment
pattern by using the following sequence.</P>
<P><STRONG>Screen Alignment Display (DECALN)</STRONG></P>
<PRE CLASS="code">ESC # 8
033 043 070</PRE>
<P>Fills screen with uppercase E's for screen focus and alignment. This command
is used by DIGITAL Manufacturing and Field Service personnel.</P>
<H4 ID="S5.5.2.30">Keyboard Indicator</H4>
<P>You can program the L1 indicator (LED) for specific
applications. Turn L1 on or off by using the following sequences.</P>
<P><STRONG>Load LED (DECLL)</STRONG></P>
<PRE CLASS="code">ESC [ 0 q
033 133 060 161</PRE>
<P>Turns L1 off.</P>
<PRE CLASS="code">ESC [ 1 q
033 133 061 161</PRE>
<P>Turns L1 on.</P>
<H3 ID="S5.5.3">VT52-Compatible Sequences</H3>
<P>VT52-compatible sequences meet private DIGITAL standards. Therefore,
the terminal can use existing software designed for previous terminals
(such as the VT52). You can select VT52 compatibility from the keyboard
in SET-UP (<A HREF="chapter3.html">Chapter 3</A>), or the computer can use a sequence. (See <A HREF="#S5.5.2">ANSI-Compatible
Sequences</A> in this chapter).</P>
<H4 ID="S5.5.3.1">Modes</H4>
<P>In VT52 mode, you cannot select most terminal features by using
sequences. You can, however, select the following three modes by using
sequences: ANSI mode, application keypad mode on, and application
keypad mode off (numeric keypad mode on).</P>
<H4 ID="S5.5.3.2">ANSI/VT52 Compatibility</H4>
<P>The terminal is compatible with both ANSI
and private DIGITAL standards. Therefore, the terminal can use new software
that meets ANSI standards and existing software designed for previous
terminals (such as the VT52). ANSI-compatible sequences meet
standards X3.64-1979 and X3.41-1974. You use ANSI mode to select
most terminal features; the terminal uses the same features when it
switches to VT52 mode. You cannot, however, change most of these features
in VT52 mode. Select ANSI compatibility by using the following sequence.</P>
<P><STRONG>ANSI Mode (DECANM)</STRONG></P>
<PRE CLASS="code">ESC <
033 074</PRE>
<P>The terminal interprets all sequences according to ANSI standards X3.64-1979
and X3.41-1974. The VT52 escape sequences described in this
chapter are not recognized.</P>
<H4 ID="S5.5.3.3">Cursor Positioning</H4>
<P>The cursor indicates the active screen position
where the next character will appear. You must select the margins for
VT52 mode in ANSI mode. If you do not select margins, the terminal uses
the complete screen. The cursor moves:</P>
<UL>
<LI>One column to the right when a character appears</LI>
<LI>One line down after a linefeed, form feed, or vertical tab. (Linefeed/new
line may also move the cursor to left margin).</LI>
<LI>To the left margin after a carriage return</LI>
<LI>One column to the left after a backspace</LI>
<LI>To the next tab stop (or right margin if no tabs are set) after a horizontal
tab character.</LI>
</UL>
<P>You can also move the cursor by using the following sequences.</P>
<P><STRONG>Cursor Up</STRONG></P>
<PRE CLASS="code">ESC A
033 101</PRE>
<P>Moves cursor up one line in same column. Cursor stops at top margin.</P>
<P><STRONG>Cursor Down</STRONG></P>
<PRE CLASS="code">ESC B
033 102</PRE>
<P>Moves cursor down one line in same column. Cursor stops at bottom
margin.</P>
<P><STRONG>Cursor Right</STRONG></P>
<PRE CLASS="code">ESC C
033 103</PRE>
<P>Moves cursor one column to right. Cursor stops at right margin.</P>
<P><STRONG>Cursor Left</STRONG></P>
<PRE CLASS="code">ESC D
033 104</PRE>
<P>Moves cursor one column to left. Cursor stops at left margin.</P>
<P><STRONG>Cursor to Home</STRONG></P>
<PRE CLASS="code">ESC H
033 110</PRE>
<P>Moves cursor to home position.</P>
<P><STRONG>Direct Cursor Address</STRONG></P>
<PRE CLASS="code">ESC Y line column
033 131 *** ***</PRE>
<P>Moves cursor to specified line and column. Line and column numbers are
ASCII character whose codes are their octal value plus octal 037. For
example, line 1 column 8 parameters are octal 040 (first line) and octal
050 (eighth column).</P>
<P><STRONG>Reverse Linefeed</STRONG></P>
<PRE CLASS="code">ESC I
033 111</PRE>
<P>Moves cursor up one line in same column. If cursor is at top margin,
screen performs scroll-down.</P>
<H4 ID="S5.5.3.4">Keypad Character Selection</H4>
<P>The numeric keypad generates either numeric
characters or control functions. Select application keypad mode to
generate control functions. Exit application keypad mode (select numeric
keypad mode) to generate numeric characters. See <A HREF="table5-14.html">Table 5-14</A> for the
characters generated by the keypad. Enter and exit application keypad
mode by using the following sequences.</P>
<P CLASS="note">NOTE: When you power up or use a Reset command, the terminal exits
application keypad mode (selects numeric keypad mode). This mode is
also selected during communication line connections, except full-duplex
no modem control (FDX A). See <A HREF="chapter6.html">Chapter 6</A> for more information about
communication line disconnects.</P>
<P><STRONG>Enter Application Keypad Mode</STRONG></P>
<PRE CLASS="code">ESC =
033 075</PRE>
<P>Keypad generates sequences used by the applications program.</P>
<P><STRONG>Exit Application Keypad Mode (Numeric Keypad Mode)</STRONG></P>
<PRE CLASS="code">ESC >
033 076</PRE>
<P>Keypad generates characters that match the numeric, comma, period,
and minus sign keys on main keyboard.</P>
<H4 ID="S5.5.3.5">Character Sets and Selection</H4>
<P>In VT52 mode, the terminal uses either
the US/UK character set selected in SET-UP or the special characters
and line drawing character set. Tables <A HREF="table5-11.html">5-11</A> and <A HREF="table5-12.html">5-12</A> show the United
Kingdom and United States character sets. <A HREF="table5-13.html">Table 5-13</A> shows the special
characters and line drawing character set. <A HREF="table5-15.html">Table 5-15</A> compares the special
characters and line drawing character set to VT52 graphics mode
(character set). Select the character sets by using the following sequences.</P>
<P CLASS="note">NOTE: The character set selected in SET-UP is used after all communication
line connections, except full-duplex no modem control (FDX A).
See <A HREF="chapter6.html">Chapter 6</A> for more information about communication.</P>
<P><STRONG>Enter Graphics Mode</STRONG></P>
<PRE CLASS="code">ESC F
033 106</PRE>
<P>Selects the special characters and line drawing character set.</P>
<P><STRONG>Exit Graphics Mode</STRONG></P>
<PRE CLASS="code">ESC G
033 107</PRE>
<P>Selects the character set selected in SET-UP.</P>
<H4 ID="S5.5.3.6">Erasing</H4>
<P>Erasing removes characters from the screen. Erased characters
are lost. Erase characters by using the following sequences.</P>
<P><STRONG>Erase to End of Line</STRONG></P>
<PRE CLASS="code">ESC K
033 113</PRE>
<P>Erases all characters from cursor to end of current line, including cursor
position. Cursor does not move.</P>
<P><STRONG>Erase to End of Screen</STRONG></P>
<PRE CLASS="code">ESC J
033 112</PRE>
<P>Erases all characters from cursor to end of screen, including cursor
position. Cursor does not move.</P>
<H4 ID="S5.5.3.7">Printing</H4>
<P>The terminal has a serial printer interface for local printing. The
computer can select all print operations by using sequences. You can
only select two print operations from the keyboard, auto print and print
screen.</P>
<P>When you print characters from the screen, terminal and printer tab stops
are ignored. Characters printed are spaced with the space (SP, octal
040) character. The terminal transmits a carriage return and linefeed -
but not a space character - after the last printable character of a line.</P>
<P>A line of double-height characters prints as two identical lines of single-width
characters. Double-width characters print as single-width characters
on a single line.</P>
<P>Before selecting a print operation, check the printer status by using the
printer status report (DSR) in ANSI mode. Do not select a print operation if
the serial printer is not ready to print. Select print operations by using the
following sequences.</P>
<P><STRONG>Auto Print</STRONG></P>
<PRE CLASS="code">ESC ^
033 136</PRE>
<P>Turns on auto print. A display line prints after you move cursor off the line,
using a linefeed, form feed, or vertical tab (also transmitted to printer).</P>
<P>The line also prints during an auto wrap. Auto wrap lines end with CR, LF.</P>
<PRE CLASS="code">ESC _
033 137</PRE>
<P>Turns off auto print.</P>
<P CLASS="note">NOTE: Printer controller has a higher priority than auto print. Therefore,
you can select printer controller and print characters during auto print.</P>
<P><STRONG>Print Controller</STRONG></P>
<PRE CLASS="code">ESC W
033 127</PRE>
<P>Turns on printer controller. The terminal transmits received characters to
printer without displaying them. The terminal does not insert or delete
spaces, provide line delimiters, or select printer character set.</P>
<PRE CLASS="code">ESC X
033 130</PRE>
<P>Turns off printer controller. Always move printhead to left margin before
turning off printer controller.</P>
<P><STRONG>Print Cursor Line</STRONG></P>
<PRE CLASS="code">ESC V
033 135</PRE>
<P>Prints display line with cursor. Cursor position does not change. Print cursor
line ends when the line prints.</P>
<P><STRONG>Print Screen</STRONG></P>
<PRE CLASS="code">ESC ]
033 126</PRE>
<P>Prints the screen. Printer extent (DECPEX) selects full screen or scrolling
region to print. Select scrolling region by using DECSTBM sequence. Print
screen ends when screen prints.</P>
<H4 ID="S5.5.3.8">Reports</H4>
<P>The terminal transmits reports in response to computer
requests. The terminal generates only one report in VT52 mode. The report
requests and responses are as follows.</P>
<P><STRONG>Identify</STRONG></P>
<PRE CLASS="code">ESC Z
033 132</PRE>
<P>Terminal sends an identify sequence to computer.</P>
<PRE CLASS="code">ESC / Z
033 057 132</PRE>
<P>VT102 response to identify sequence. (Same as VT52).</P>
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