Video Systems Reference Manual
Character Cell Display

Set/Reset Text Cursor Enable Mode — DECTCEM

Levels: 2-4

Purpose: Select whether the text cursor symbol in the display has a visual representation.

CSI ? 25 h

CSI ? 25 l

Description: A conforming device shall provide a means of enabling or disabling the visible cursor symbol. This mode shall apply only to the text cursor symbol implemented by the Character Cell Display service class. In the set state (Text Cursor On), which is the default, the text cursor symbol will be displayed. In the reset state (Text Cursor Off), the text cursor symbol will not be displayed.

When a request is received to turn off the cursor, it will be done immediately (if not already off). If a request is received to enable the cursor, and the cursor is not already on, the cursor will remain off for a small "initial" cycle, after which it will become visible and begin its normal blinking cycle. This makes the cursor blink with a steady duty cycle regardless of how fast it is turned on and off.

Notes:

1. There is some concern that a program might inadvertently leave the text cursor turned off. It is suggested that entering SETUP mode will always turn on the text cursor while in SETUP mode, but that normally it be restored to its previous state upon exiting SETUP mode. Also, a means should be provided in SETUP mode to force the text cursor to be re-enabled.

State Affected:

• text_cursor_enable_mode

Algorithm:

void set_text_cursor_enable_mode()
{
if (conformance_level >= LEVEL_2)
    text_cursor_enable_mode = TEXT_CURSOR_ON;
}


void reset_text_cursor_enable_mode()
{
if (conformance_level >= LEVEL_2)
    text_cursor_enable_mode = TEXT_CURSOR_OFF;
}

Known Deviations: None

Set Top And Bottom Margins — DECSTBM

Levels: 1-4

Purpose: Change the top and bottom margin settings for the scrolling region.

CSI   Pt  ;  Pb  r      default Pt: 1
9/11  Pt  ;  Pb  7/2    default Pb: last line

Description: The DECSTBM control sets the values of the Top and Bottom Margins of the scrolling region. The new settings are determined by the parameter values. The first parameter sets the value of the Top Margin, and the second parameter sets the value of the Bottom Margin. The default settings if either or both parameters are omitted are the boundaries of the Logical Display Page: one (1) for the Top Margin and twenty-four (24) for the Bottom Margin when the Page Size is 24 lines.

Notes:

1. Execution of this control causes the Active Position to be set to the page origin obeying Origin Mode (DECOM): First column of first line if Origin Mode is in the reset (Absolute) state; Top and Left Margins if Origin Mode is in the set (Displaced) state.

2. If the value specified for the Top Margin is equal to or greater than the value specified for the Bottom Margin, this control will be ignored (not executed).

3. If the value specified for the Bottom Margin is greater than the number of lines in the Logical Display Page, this control will be ignored (not executed).

State Affected:

• active_position
• top_margin
• bottom_margin

Algorithm:

void set_top_and_bottom_margins(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
/* use defaults for omitted parameters */
if (parv[0] == 0) parv[0] = 1;
if (parv[1] == 0) parv[1] = lines_per_page;

if ((parv[0] < parv[1]) && (parv[1] <= lines_per_page))
  {
  top_margin = parv[0];
  bottom_margin = parv[1];
  if (origin_mode == ABSOLUTE)
    {
    active_position.line = 1;
    active_position.column = 1;
    }
  else
    {
    active_position.line = top_margin;
    active_position.column = left_margin;
    }
  }
}

Known Deviations: None

Set Left And Right Margins — DECSLRM

Levels: 4x (Horizontal Scrolling)

Purpose: Change the left and right margin settings for the scrolling region.

CSI   Pl  ;  Pr s       default Pl: 1
9/11  Pl  ;  Pr 7/3     default Pr: Last Column

Description: The DECSLRM control sets the values of the Left and Right Margins of the scrolling region. The new settings are determined by the parameter values. The first parameter sets the value of the Left Margin, and the second parameter sets the value of the Right Margin. The default settings if either or both parameters are omitted are the boundaries of the Logical Display Page: one (1) for the Left Margin and eighty (80) for the Right Margin when the Page Size is 80 columns wide.

Notes:

1. Execution of this control causes the Active Position to be set to the page origin obeying Origin Mode (DECOM): First column of first line if Origin Mode is in the reset (Absolute) state; Top and Left Margins if Origin Mode is in the set (Displaced) state.

2. If the value specified for the Left Margin is equal to or greater than the value specified for the Right Margin, this control will be ignored (not executed).

3. If the value specified for the Right Margin is greater than the number of columns in the Logical Display Page, this control will be ignored (not executed).

4. This control function is only recognized when DECLRMM (Left Right Margin Mode) is set.

5. Setting the margins to other than their default values (the boundaries of the Logical Display Page) may disable smooth scrolling (DECSCLM).

State Affected:

• active_position
• left_margin
• right_margin

Algorithm:

void set_left_and_right_margins(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
if ( (conformance_level == LEVEL_4) &&
     (level_4_extensions[HORIZONTAL_SCROLL] == TRUE) &&
     (left_right_margins_mode == SETABLE) )
  {
  /* use defaults for omitted parameters */
  if (parv[0] == 0) parv[0] = 1;
  if (parv[1] == 0) parv[1] = columns_per_page;

  if ((parv[0] < parv[1]) && (parv[1] <= columns_per_page))
    {
    left_margin = parv[0];
    right_margin = parv[1];
    if (origin_mode == ABSOLUTE)
      {
      active_position.line = 1;
      active_position.column = 1;
      }
    else
      {
      active_position.line = top_margin;
      active_position.column = left_margin;
      }
    }
  }
}

Known Deviations: None

Set/Reset Left Right Margin Mode — DECLRMM

Levels: 4x (Horizontal Scrolling)

Purpose: Change the state of Left Right Margin Mode between Not Available (reset) and Available (set).

CSI ? 69 h    (Available)

CSI ? 69 l    (Not Available - default)

Description: DECLRMM is a parameter to the Set Mode and Reset Mode commands. In the reset state, the left and right scrolling margins in every page may not be moved through the DECSLRM command, they are set to be at the extremes of the page. In the set state, DECSLRM commands are recognized, however, no line attributes other than Single Wide may be used.

When DECLRMM is set, all line attributes currently in Page Memory for the Session will be reset to Single Wide, Single High, and DECDWL and DECDHL escape sequences, to change the line attribute to Double Wide or Double Wide and High, will be ignored.

State Affected:

• left_right_margins_mode
• line_rendition[MAX_NUM_LINES]
• left_margin
• right_margin

Algorithm:

void set_left_right_margins_mode()
{
int i;
if ( (conformance_level == LEVEL_4) &&
     (level_4_extensions[HORIZONTAL_SCROLL] == TRUE) )
  {
  for (i=0; i<MAX_NUM_LINES; i++)
    {
    line_rendition[i] = SINGLE_WIDTH;
    }
  left_right_margins_mode = SETABLE;
  }
}


void reset_left_right_margins_mode()
{
if ( (conformance_level == LEVEL_4) &&
     (level_4_extensions[HORIZONTAL_SCROLL] == TRUE) )
  {
  left_margin = 1;
  right_margin = columns_per_page;
  left_right_margins_mode = FIXED;
  }
}

Known Deviations: None

Set/Reset Origin Mode — DECOM

Levels: 1-4

Purpose: Change the state of Origin Mode between Absolute (reset) and Displaced (set) origin.

CSI ? 6 h    (displaced)

CSI ? 6 l    (absolute - default)

Description: A conforming device shall allow addressing of the display area to be performed relative to either the display origin (coordinate 1,1) [reset state = absolute] or the origin of the current scrolling region (Top Margin, Left Margin) [set state = displaced]. When Origin Mode is in the set state (displaced), the Active Position cannot be moved above the Top Margin or left of the Left Margin of the scrolling region.

The DECOM controls are used the change the state of Origin Mode between Absolute and Displaced.

State Affected:

• origin_mode
• active_position

Algorithm:

void set_origin_mode()
{
origin_mode = DISPLACED;
active_position.line = top_margin;
active_position.column = left_margin;
}


void reset_origin_mode()
{
origin_mode = ABSOLUTE;
active_position.line = 1;
active_position.column = 1;
}

Known Deviations: None

Set/Reset Scrolling Mode — DECSCLM

Levels: 1-4

Purpose: Change the state of Scrolling Mode between Jump (reset) and Slow (set) scrolling.

CSI ? 4 h    (smooth - default)

CSI ? 4 l    (jump)

Description: A conforming device shall provide the capability of selecting either jump scrolling [reset state = jump] and slow scrolling [set state = slow]. Jump scrolling is defined as scrolling of the display as fast as the device permits, to a maximum which will be implementation defined. Slow scrolling is defined as scrolling of the display at a rate of approximately 6 text lines per second. The intention of slow scrolling is to move text through the display at a rate which makes it "recognizable", but not necessarily readable. (i.e., it is not guaranteed that it will appear slowly enough for the user to scan read the entire text). The scrolling speed applies to vertical scrolling of the scrolling region of the display, which can be set as any combination of adjacent lines.

The DECSCLM controls are used to change the state of Scrolling Mode between Jump (reset state) and Slow (set scrolling.

Notes:

1. Some implementations may offer a choice of additional scrolling speeds in Set-Up. The reset state of DECSCLM will select the speed closest to 6 lines per second.

2. Setting the left or right margins to other than their default values (the boundaries of the Logical Display Page) may temporarily disable smooth scrolling (guideline), but will not affect the state of Scrolling Mode.

State Affected:

• scrolling_mode

Algorithm:

void set_scrolling_mode()
{
scrolling_mode = SLOW;
}


void reset_scrolling_mode()
{
scrolling_mode = JUMP;
}

Known Deviations: Workstation terminal emulators which do not have scrolling hardware do not implement this control (DECterm, UIS).

Index — IND

Levels: 1-4

Purpose: Move the Active Position downward one line, scrolling if necessary.

IND
8/4     (ESC D)

Description: The IND control moves the Active Position downward in the display by one line. If the Active Position is already at the Bottom Margin the display will scroll upward by one line. If the display scrolls, a blank line with all attributes off will appear at the bottom margin.

Notes:

1. If the Active Position is above the Bottom Margin when this control is executed, the Active Position will not move beyond the Bottom Margin. If the Active Position is below the Bottom Margin (as the result of absolute cursor positioning) it will still move downward by one line and no scrolling will occur. In this case, the Active Position will not move beyond the bottom line of the display.

2. This control is identical to the Line Feed (LF) control, except that it is not affected by the setting of New Line Mode.

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]
• active_position

Algorithm:

void index()
{
if (active_position.line == bottom_margin)
  scroll_up(top_margin, 1);
else
  if (active_position.line < lines_per_page)
    active_position.line += 1;

/* new line may have a different length - adjust column */
if (active_position.column > end_of_line(active_position.line))
  active_position.column = end_of_line(active_position.line);
}

Known Deviations:

On the VT100 and VT125, Index is affected by the setting of New Line Mode, in the same manner as Line Feed.

Reverse Index — RI

Levels: 1-4

Purpose: Move the Active Position upward one line, scrolling if necessary.

RI
8/13    (ESC M)

Description: The RI control moves the Active Position upward in the display by one line. If the Active Position is already at the Top Margin the display will scroll downward by one line. If the display scrolls, a blank line with all attributes off will appear at the top margin.

Notes:

1. If the Active Position is below the Top Margin when this control is executed, the Active Position will not move beyond the Top Margin. If the Active Position is above the Top Margin (as the result of absolute cursor positioning) it will still move upward by one line and no scrolling will occur. In this case, the Active Position will not move beyond the first line of the display.

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]
• active_position

Algorithm:

void reverse_index()
{
if (active_position.line == top_margin)
  scroll_down(top_margin, 1);
else
  if (active_position.line > 1)
    active_position.line -= 1;

/* new line may have a different length - adjust column */
if (active_position.column > end_of_line(active_position.line))
  active_position.column = end_of_line(active_position.line);
}

Known Deviations: None

Forward Index — DECFI

Levels: 4x (Horizontal Scrolling)

Purpose: Move the Active Position forward one column, scrolling if necessary.

ESC   9
1/11  3/9

Description: The DECFI control causes the active position to move forward one column. If the active position was already at the right margin, the contents of the Logical Display Page within the right, left, top and bottom margins shifts left one column. The column shifting beyond the left margin is deleted. A new column is inserted at the right margin with all attributes turned off and the cursor appears in this column.

If the active position is outside the left or right margin when the command is received the active position moves forward one column. If the active position was at the right edge of the page, the command is ignored.

Notes on DECFI:

1. Lines of text are shifted one column regardless of their line attributes. This means double-wide and double-size lines will appear to shift twice as fast as single-width lines.

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]
• active_position

Algorithm:

void decfi()
{
if ( (conformance_level == LEVEL_4) &&
     (level_4_extensions[HORIZONTAL_SCROLL] == TRUE) )
  {
  if (active_position.column == right_margin)
    scroll_left(left_margin, 1);
  else
    if (active_position.column < columns_per_page)
      active_position.column += 1;

  /* active line may not be columns_per_page long */
  if (active_position.column > end_of_line(active_position.line))
    active_position.column = end_of_line(active_position.line);
  }
}

Known Deviations: None

Back Index — DECBI

Levels: 4x (Horizontal Scrolling)

Purpose: Move the Active Position backward one column, scrolling if necessary.

ESC   6
1/11  3/6

Description: The DECBI control causes the active position to move backward one column. If the active position was already at the left margin, the contents of the Logical Display within the left, right, top and bottom margin shifts right one column. The column shifted beyond the right margin is deleted. A new column is inserted at the left margin with all attributes turned off and the cursor appears in this column.

If the active position is outside the left or right margin when the command is received the active position moves backwards one column. If the active position was at the left edge of the page, the command is ignored.

Notes on DECBI:

1. Lines of text are shifted one column regardless of their line attributes. This means double-wide and double-size lines will appear to shift twice as fast as single-width lines.

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]
• active_position

Algorithm:

void decbi()
{
if ( (conformance_level == LEVEL_4) &&
     (level_4_extensions[HORIZONTAL_SCROLL] == TRUE) )
  {
  if (active_position.column == left_margin)
    scroll_right(left_margin, 1);
  else
    if (active_position.column > 1)
      active_position.column -= 1;
  }
}

Known Deviations: None

Cursor Up — CUU

Levels: 1-4

Purpose: Move the Active Position upward by n lines.

CSI     Pn      A               default Pn: 1
9/11    3/?     4/1

Description: The CUU control moves the Active Position upward in the display. The distance moved is determined by the parameter value. A parameter value of zero or one moves the Active Position upward by one line. A parameter value of n moves the Active Position upward by n lines.

Notes:

1. If the Active Position is at or below the Top Margin when the CUU control is executed, and an attempt is made to move the Active Position above the Top Margin, the control will be executed until the Active Position reaches the Top Margin. The Active Position will not move beyond the Top Margin.

2. If the Active Line is above the Top Margin when the CUU control is executed (due to absolute cursor positioning) and an attempt is made to move the Active Position outside of the addressable display, the control will be executed until the Active Position reaches the first line of the Page. The Active Position will not move beyond the first line of the Page.

3. No scrolling will occur as a result of this control.

4. If the line to which the Active Position is moved contains fewer columns than the Active Column, the Active Column is set to the end of that line. (This condition will only occur if the Active Line is a single-width line, and the line to which the Active Position is moved is a double-width or double-height line. The Active Column is not affected by the length of lines it moves over by a repeat move caused by a parameter value greater than one.)

State Affected:

• active_position

Algorithm:

void cursor_up(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
  short int n;
if (parv[0] == 0) n = 1;
else n = parv[0];
if (active_position.line >= top_margin)
  {
  if ((active_position.line - n) >= top_margin)
    active_position.line -= n;
  else
    active_position.line = top_margin;
  }
else
  {
  if ((active_position.line - n) >= 1)
    active_position.line -= n;
  else
    active_position.line = 1;
  }

/* new line may have a different length - adjust column */
if (active_position.column > end_of_line(active_position.line))
  active_position.column = end_of_line(active_position.line);
}

Known Deviations: None

Cursor Down — CUD

Levels: 1-4

Purpose: Move the Active Position downward by n lines.

CSI     Pn      B               default Pn: 1
9/11    3/?     4/2

Description: The CUD control moves the Active Position downward in the display. The distance moved is determined by the parameter value. A parameter value of zero or one moves the Active Position downward by one line. A parameter value of n moves the Active Position downward by n lines.

Notes:

1. If the Active Position is at or above the Bottom Margin when the CUD control is executed, and an attempt is made to move the Active Position below the Bottom Margin, the control will be executed until the Active Position reaches the Bottom Margin. The Active Position will not move beyond the Bottom Margin.

2. If the Active Position is below the Bottom Margin when the CUD control is executed (due to absolute cursor positioning) and an attempt is made to move the Active Position outside of the addressable display, the control will be executed until the Active Position reaches the bottom line of the Page. The Active Position will not move beyond the bottom line of the Page.

3. No scrolling will occur as a result of this control.

4. If the line to which the Active Position is moved contains fewer columns than the Active Column, the Active Column is set to the end of that line. (This condition will only occur if the Active Line is a single-width line, and the line to which the Active Position is moved is a double-width or double-height line. The Active Column is not affected by the length of lines it moves over by a repeat move caused by a parameter value greater than one.)

State Affected:

• active_position

Algorithm:

void cursor_down(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
  short int n;
if (parv[0] == 0) n = 1;
else n = parv[0];
if (active_position.line <= bottom_margin)
  {
  if ((active_position.line + n) <= bottom_margin)
    active_position.line += n;
  else
    active_position.line = bottom_margin;
  }
else
  {
  if ((active_position.line + n) <= lines_per_page)
    active_position.line += n;
  else
    active_position.line = lines_per_page;
  }

/* new line may have a different length - adjust column */
if (active_position.column > end_of_line(active_position.line))
  active_position.column = end_of_line(active_position.line);
}

Known Deviations: None

Cursor Forward — CUF

Levels: 1-4

Purpose: Move the Active Position forward by n columns.

CSI     Pn      C               default Pn: 1
9/11    3/?     4/3

Description: The CUF control moves the Active Position forward in the display. The distance moved is determined by the parameter value. A parameter value of zero or one moves the Active Position forward by one column. A parameter value of n moves the Active Position forward by n columns.

Notes:

1. If the Active Position is at or inside the Right Margin when the CUF control is executed, and an attempt is made to move the Active Position beyond the Right Margin, the control will be executed until the Active Position reaches the Right Margin. The Active Position will not move beyond the Right Margin.

2. If the Active Position is beyond the Right Margin when the CUF control is executed (due to absolute cursor positioning) and an attempt is made to move the Active Position outside of the addressable display, the control will be executed until the Active Position reaches the last column of the Active Line. The Active Position will not move beyond the last column of the Active Line.

3. No scrolling will occur as a result of this control.

State Affected:

• active_position

Algorithm:

void cursor_forward(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
  short int n;
if (parv[0] == 0) n = 1;
else n = parv[0];
if (active_position.column <= right_margin)
  {
  if ((active_position.column + n) <= right_margin)
    active_position.column += n;
  else
    active_position.column = right_margin;
  }
else
  {
  if ( (active_position.column + n) <=
       end_of_line(active_position.line) )
    active_position.column += n;
  else
    active_position.column = end_of_line(active_position.line);
  }
}

Known Deviations: None

Cursor Backward — CUB

Levels: 1-4

Purpose: Move the Active Position backward by n columns.

CSI     Pn      D               default Pn: 1
9/11    3/?     4/4

Description: The CUB control moves the Active Position backward in the display. The distance moved is determined oy the parameter value. A parameter value of zero or one moves the Active Position backward by one one column. A parameter value of n moves the Active Position backward by n columns.

Notes:

1. If the Active Position is at or inside the Left Margin when the CUB control is executed, and an attempt is made to move the Active Position beyond the Left Margin, the control will be executed until the Active Position reaches the Left Margin. The Active Position will not move beyond the Left Margin.

2. If the Active Position is beyond the Left Margin when the CUB control is executed (due to absolute cursor positioning) and an attempt is made to move the Active Position outside of the addressable display, the control will be executed until the Active Position reaches the first column of the Active Line. The Active Position will not move beyond the first column of the Active Line.

3. No scrolling will occur as a result of this control.

State Affected:

• active_position

Algorithm:

void cursor_backward(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
  short int n;
if (parv[0] == 0) n = 1;
else n = parv[0];
if (active_position.column >= left_margin)
  {
  if ((active_position.column - n) >= left_margin)
    active_position.column -= n;
  else
    active_position.column = left_margin;
  }
else
  {
  if ((active_position.column - n) >= 1)
    active_position.column -= n;
  else
    active_position.column = 1;
  }
}

Known Deviations: None

Cursor Position — CUP

Levels: 1-4

Purpose: To position the Active Position at an absolute line and column address.

CSI   Pl  ;  Pc   H     default Pl: 1
9/11  3/? ;  3/?  4/8   default Pc: 1

Description: The CUP control moves the Active Position to an absolute line and column address as specified by the parameter values. The first parameter specifies the new line address, and the second parameter specifies the new column address. If either parameter is omitted, or is explicitly set to zero (0), that parameter value will default to one (1).

Notes:

1. This control is affected by the setting of Origin Mode. If Origin Mode is reset, addressing is performed relative to the page origin (first column in the first line). If Origin Mode is set, addressing is performed relative to the origin of the current scrolling region (the top and left margin).

2. If an attempt is made to move the Active Position outside of the addressable display area (the entire screen if Origin Mode is reset, or the scrolling region if Origin Mode is set), the Active Position will be moved in the direction indicated to the boundary of the addressable area, but will not be moved beyond the boundary of the addressable area.

State Affected:

• active_position

Algorithm:

void cursor_position(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
  line_t y;
  column_t x;
y = parv[0];
x = parv[1];
if (y == 0) y = 1;
if (x == 0) x = 1;
if (origin_mode == DISPLACED)
  {
  if ( ((top_margin-1) + y) <= bottom_margin )
    active_position.line = (top_margin-1) + y;
  else
    active_position.line = bottom_margin;

  if ( ((left_margin-1) + x) <= right_margin )
    active_position.column = (left_margin-1) + x;
  else
    active_position.column = right_margin;
  }
else
  {
  if (y <= lines_per_page)
    active_position.line = y;
  else
    active_position.line = lines_per_page;

  if (x <= end_of_line(active_position.line))
    active_position.column = x;
  else
    active_position.column = end_of_line(active_position.line);
  }
}

Known Deviations: None

Horizontal/Vertical Position — HVP

Levels: 1-4

Purpose: Move the Active Position to an absolute line and column address. (fallback implementation)

CSI   Pl  ;  Pc  f      default Pl: 1
9/11  Pl  ;  Pc  6/6    default Pc: 1

Description: The HVP control moves the Active Position to an absolute line and column address as specified by the parameter values. The first parameter specifies the new line address, and the second parameter specifies the new column address. If either parameter is omitted, or is explicitly set to zero (0), that parameter value will default to one (1).

Notes:

1. The HVP control is provided for interface compatibility with printing terminals. This implementation is not in conformance with existing standards. Conforming software will use the Cursor Position control to affect movement of the cursor, since the operation of Horizontal/Vertical Position may be redefined in future levels of the architecture.

2. This control is affected by the setting of Origin Mode. If Origin Mode is reset, addressing is performed relative to the page origin (first column in the first line). If Origin Mode is set, addressing is performed relative to the origin of the current scrolling region (the top and left margin).

3. If an attempt is made to move the Active Position outside of the addressable display area (the entire screen if Origin Mode is reset, or the scrolling region if Origin Mode is set), the Active Position will be moved in the direction indicated to the boundary of the addressable area, but will not be moved beyond the boundary of the addressable area.

State Affected:

• active_position

Algorithm:

void horizontal_vertical_position(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
  /* steal code from CUP */
  cursor_position(parv);
}

Known Deviations: None

Cursor Position Report — CPR

Levels: 1-4

Purpose: Report the line and column address of the Active Position.

CSI   6    n
9/11  3/6  6/14

CSI   Pl   ;  Pc   R            default Pl: 1
9/11  3/?  ;  3/?  5/2          default Pc: 1

Description: The CPR control is transmitted by the terminal in response to a specific Device Status Report (DSR) control. The parameter values indicate the Active Line and Active Column values at the time the DSR control is received by the terminal.

Notes:

1. This control is affected by the setting of Origin Mode. If Origin Mode is reset, addressing is performed relative to the page origin (first column in the first line). If Origin Mode is set, addressing is performed relative to the origin of the current scrolling region (the Top and Left Margin).

State Affected:

• none

Algorithm:

void cursor_position_report()
{
  line_t y;
  column_t x;
if (origin_mode == DISPLACED)
  {
  y = active_position.line - top_margin + 1;
  x = active_position.column - left_margin + 1;
  }
else
  {
  y = active_position.line;
  x = active_position.column;
  }
send_char(0x9B, host_port);  /* CSI */
send_int(y, host_port);
send_char(';', host_port);
send_int(x, host_port);
send_char('R', host_port);
}

Known Deviations: None

Extended Cursor Position Report — DECXCPR

Levels: 3x (Windowing), 4

Purpose: Report the line, column, and page address of the Active Position.

CSI   ?     6    n
9/11  3/15  3/6  6/14

CSI   ?     Pl   ;     Pc   ;     Pp   R
9/11  3/15  3/?  3/11  3/?  3/11  3/?  5/2

default Pl, Pc, Pp: 1

Description: The DECXCPR control is transmitted by the terminal in response to a specific Device Status Report (DSR) control. The parameter values indicate the Active Line, Column, and Page values at the time the DSR control is received by the terminal. The default condition with no parameters present, or parameters of 0, is equivalent to a cursor at the home position on the first Page.

Notes:

1. This control is affected by the setting of Origin Mode. If Origin Mode is reset, addressing is performed relative to the page origin (first column in the first line). If Origin Mode is set, addressing is performed relative to the origin of the current scrolling region (the Top and Left Margin).

State Affected: None

Algorithm:

void x_cursor_position_report()
{
  line_t y;
  column_t x;
if (origin_mode == DISPLACED)
  {
  y = active_position.line - top_margin + 1;
  x = active_position.column - left_margin + 1;
  }
else
  {
  y = active_position.line;
  x = active_position.column;
  }
send_char(0x9B, host_port);  /* CSI */
send_char('?', host_port);
send_int ( y , host_port);
send_char(';', host_port);
send_int ( x,  host_port);
send_char(';', host_port);
send_char(active_position.page, host_port);
send_char('R', host_port);
}

Known Deviations: None

Set/Reset New Line Mode — LNM

Levels: 1-4

Purpose: Change the state of New Line Mode between New Line Off (reset) and New Line On (set).

CSI 20 h

CSI 20 l

Description: A conforming device shall provide a means of selecting whether a received Line Feed (LF), Vertical Tab (VT), or Form Feed (FF) character shall be treated as a single instance of that character [reset state = no_new_line], or that each of these characters is handled on receipt by additionally returning the Active Position to the first column of the display [set state = new_line]. It should be noted that setting of this mode also affects the processing of the Carriage Return (CR) key, which transmits a two-code sequence (CR LF) when New Line Mode is in the set state.

(Note: This mode should not be used in the set state by conforming software.)

State Affected:

• new_line_mode

Algorithm:

void set_new_line_mode()
{
new_line_mode = NEW_LINE_ON;
}


void reset_new_line_mode()
{
new_line_mode = NEW_LINE_OFF;
}

Known Deviations: None

Carriage Return — CR

Levels: 1-4

Purpose: Move the Active Position to the Left Margin.

CR
0/13

Description: The CR control moves the Active Position to the Left Margin. If the Active Position is before the left margin, or outside the top and bottom margins, the cursor moves to the first column of the Active Line.

State Affected:

• active_position

Algorithm:

void_carriage_return()
{
if ((active_position.column >= left_margin) &&
    (active_position.line >= top_margin) &&
    (active_position.line <= bottom_margin))
  active_position.column = left_margin;
else
  active_position.column = 1;
}

Known Deviations: None

Line Feed — LF

Levels: 1-4

Purpose: Move the Active Position downward one line, scrolling if necessary.

LF
0/10

Description: The LF control moves the Active Position downward in the display by one line. If the Active Position is already at the Bottom Margin the display will scroll upward by one line.

Notes:

1. If the Active Position is above the Bottom Margin when this control is executed, the Active Position will not move beyond the Bottom Margin.

2. If the Active Position is below the Bottom Margin when this control is executed (as the result of absolute cursor positioning) it will still move downward by one line and no scrolling will occur. In this case, the Active Position will not move beyond the bottom line of the display.

3. If the line to which the Active Position is moved contains fewer columns than the Active Column, the Active Column is set to the end of that line.

4. This control is affected by the setting of New Line Mode. If this mode is reset, no change will occur in the Active Column unless the line below the Active Line is shorter than the Active Line (see note 2). If the mode is set, the control causes the Active Column to be set to the first column of the line into which the Active Position is moved. Conforming software is recommended to use the two character sequence (CR LF) rather than New Line mode for widest compatibility.

5. Note that the fundamental differences between this control and the CUD control are the effect of New Line Mode and the occurrence of scrolling on reaching the Bottom Margin.

6. The LF control is identical in function to the IND (Index) control when New Line Mode is in the reset (No New Line) state.

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]
• active_position

Algorithm:

void line_feed()
{
if (new_line_mode == NEW_LINE_ON) carriage_return();
if (active_position.line == bottom_margin)
  scroll_up(top_margin, 1);
else
  if (active_position.line < lines_per_page)
    active_position.line += 1;

/* new line may have different length - adjust column */
if (active_position.column > end_of_line(active_position.line))
  active_position.column = end_of_line(active_position.line);
}

Known Deviations: None

Vertical Tab — VT

Levels: 1-4

Purpose: Move the Active Position downward one line, scrolling if necessary. (fallback implementation)

VT
0/11

Description: The VT control moves the Active Position downward in the display by one line. If the Active Position is already at the Bottom Margin the display will scroll upward by one line.

Notes:

1. The implementation of the VT control is a fallback mechanism for display terminals which is intended to provide compatibility with printers which correctly implement this function.

2. This control is identical in function to the Line Feed (LF) control. It is provided for software compatibility with printer output. It should be noted, however, that printers will implement this function differently. It is therefore recommended that software use the Line Feed control to perform this function instead of Vertical Tab.

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]
• active_position

Algorithm:

void vertical_tab()
{
line_feed();    /* fallback implementation */
}

Known Deviations: None

Form Feed — FF

Levels: 1-4

Purpose: Move the Active Position downward one line, scrolling if necessary. (fallback implementation)

FF
0/12

Description: The FF control moves the Active Position downward in the display by one line. If the Active Position is already at the Bottom Margin the display will scroll upward by one line.

Notes:

1. The implementation of the FF control is a fallback mechanism for display terminals which is intended to provide compatibility with printers which correctly implement this function.

2. This control is identical in function to the Line Feed (LF) control. It is provided for software compatibility with printer output. It should be noted, however, that printers will implement this function differently. It is therefore recommended that software use the Line Feed control to perform this function instead of Form Feed.

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]
• active_position

Algorithm:

void form_feed()
{
line_feed();    /* fallback implementation */
}

Known Deviations: None

Back Space — BS

Levels: 1-4

Purpose: Move the Active Position one column to the left.

BS
0/8

Description: The BS control moves the Active Position backward in the display by one column.

Notes:

1. If the Active Position is at or inside the Left Margin and within the Scroll Area, it will not move beyond the Left Margin.

2. If the Active Position is already before the Left Margin, the Active Position will move left one column unless it is at the first column of the Active Line. The Active Position will not move beyond the beginning of the Active Line.

3. The BS control is not affected in any way by the setting of Auto Wrap Mode. Under no circumstances does the Active Position advance to the previous line on reaching the beginning of the Active Line.

State Affected:

• active_position

Algorithm:

void back_space()
{
if (active_position.column > left_margin)
  active_position.column -= 1;
else
  {
  if ( ((active_position.column != left_margin) ||
        (active_position.line < top_margin) ||
        (active_position.line > bottom_margin)) &&
       (active_position.column > 1)  )
    active_position.column -= 1;
  }
}

Known Deviations: None

Next Line — NEL

Levels: 1-4

Purpose: Move the Active Position to the Left Margin of the next line, scrolling if necessary.

NEL
8/5     (ESC E)

Description: The NEL control moves the Active Position to the Left Margin of the next line. If the Active Line is equal to the Bottom Margin, the Active Line is not incremented, but instead the display scrolls upward by one line. If the Active Position is before the left margin, or outside the top and bottom margins, it will move to the first column of the next line, but not beyond the last line on the page.

Notes:

1. This control is identical to sending Line Feed (LF) with Line Feed New Line Mode set. It is also identical to sending Carriage Return (CR) followed by Line Feed (LF). Software is recommended to always use the combination of Carriage Return followed by Line Feed (CR LF) to achieve this effect for widest compatibility.

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]
• active_position

Algorithm:

void next_line()
{
carriage_return();
line_feed();
}

Known Deviations: None

Tabulation Clear — TBC

Levels: 1-4

Purpose: Clear Horizontal Tab Stops.

CSI     Ps      g               default Ps: 0
9/11    3/?     6/7

Description: The TBC control provides a means of clearing or removing previously set Horizontal Tab Stops. The range of positions affected by this control is determined by the parameter value. An omitted parameter or a parameter value of zero (0) cause the control to clear only a tabulation stop set at the Active Column. A parameter value of three (3) causes the control to clear all Horizontal Tab Stops in the display.

State Affected:

• horizontal_tab_stops[MAX_NUM_COLUMNS]

Algorithm:

void tabulation_clear(parc, parv)
  short int parc;
  short int parv[MAX_NUM_PARAMETERS];
{
  column_t x;
  short int n;
if (parc == 0) parc = 1;
for (n=0; n<parc; n++)
  {
  if (parv[n] == 0)
    horizontal_tab_stops[active_position.column] = FALSE;
  else if (parv[n] == 3)
    for (x=1; x<= columns_per_page; x++)
      horizontal_tab_stops[x] = FALSE;
  }
}

Known Deviations: None

Horizontal Tab — HT

Levels: 1-4

Purpose: Advance the Active Position to the next Horizontal Tab Stop.

HT
0/9

Description: The HT control moves the Active Position forward in the display to the next Horizontal Tab Stop in the Active Line.

Notes:

1. If no tabulation stop is reached before the Right Margin of the Active Line (within the Scroll Area), the Active Position will be set to the Right Margin of the Active Line. If the Active Column is beyond the Right Margin or the Active Line is outside the Scroll Area (due to absolute cursor positioning), the Active Position will move to the next tab stop, or last column of the Active Line, whichever comes first.

State Affected:

• active position

Algorithm:

void horizontal_tab()
{
 boolean_t outside;
if ((active_position.line > top_margin) &&
    (active_position.line < bottom_margin))
  outside = FALSE;
else
  outside = TRUE;
if ( (active_position.column <
      end_of_line(active_position.line)) &&
     ((active_position.column != right_margin) || (outside==TRUE))
)
  active_position.column += 1;

for (; ( (active_position.column <
          end_of_line(active_position.line)) &&
         (horizontal_tab_stops[active_position.column] != TRUE) &&
         ((active_position.column != right_margin) ||
(outside==TRUE)) );
       active_position.column += 1);
}

Known Deviations: None

Horizontal Tabulation Set — HTS

Levels: 1-4

Purpose: Set a Horizontal Tab Stop at the Active Column.

HTS

8/8     (ESC H)

Description: The HTS control causes a Horizontal Tab Stop to be set at the column position indicated by the value of the Active Column at the time this control is received.

Notes:

1. None of the other Horizontal Tab Stop settings are affected by execution of this control.

State Affected:

• horizontal_tab_stops[MAX_NUM_COLUMNS]

Algorithm:

void horizontal_tabulation_set()
{
horizontal_tab_stops[active_position.column] = TRUE;
}

Known Deviations: None

Set/Reset Column Mode — DECCOLM

Levels: 1X, 2X, 3X, 4X

Purpose: Change the state of Column Mode between Eighty (reset) and One Thirty Two (set).

CSI ? 3 h

CSI ? 3 l

Description: A conforming device may provide as an extension the capability of selecting 80-column [reset state = eighty] or 132-⁠column [set state = one_thirty_two] display format.

Selecting Eighty or One_Thirty_Two Column Mode causes the display data to be cleared, the scrolling region to be eliminated, and the Active Position to be set to the display origin (1,1), even if the terminal was already in the selected state.

Notes:

1. The font used to display Page Memory may change when the number of columns on the page changes to better match the screen. Control of when the font changes may be provided as a Set-Up option.

2. If the Host Writable Status Line is enabled, receipt of this sequence will clear both the main display and the Host Writable Status Line.

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]
• line_rendition[MAX_NUM_LINES]
• active_position
• top_margin
• bottom_margin
• column_mode
• left_margin
• right_margin
• columns_per_page
• left_right_margins_mode

Algorithm:

void set_column_mode()
{
  line_t y;
  column_t x;
column_mode = ONE_THIRTY_TWO;
columns_per_page = 132;
for (y=1; y<MAX_NUM_LINES; y++)
  {
  for (x=1; x<MAX_NUM_COLUMNS; x++)
    display[y][x].code = EMPTY_CHARACTER;
  line_rendition[y] = SINGLE_WIDTH;
  }
active_position.line = 1;
active_position.column = 1;
top_margin = 1;
bottom_margin = lines_per_page;
left_margin = 1;
right_margin = columns_per_page;
left_right_margins_mode = SETABLE;
}


void reset_column_mode()
{
  line_t y;
  column_t x;
column_mode = EIGHTY;
columns_per_page = 80;
for (y=1; y<MAX_NUM_LINES; y++)
  {
  for (x=1; x<MAX_NUM_COLUMNS; x++)
    display[y][x].code = EMPTY_CHARACTER;
  line_rendition[y] = SINGLE_WIDTH;
  }
active_position.line = 1;
active_position.column = 1;
top_margin = 1;
bottom_margin = lines_per_page;
left_margin = 1;
right_margin = columns_per_page;
left_right_margins_mode = SETABLE;
}

Known Deviations: None

Set Columns Per Page — DECSCPP

Levels: 3X (Windowing), 4

Purpose: Set the number of columns per page in the Logical Display.

CSI     Pn      $       |
9/11    3/?     2/4     7/12

Description: This sequence sets the number of columns in the display page according to the numeric parameter. If the parameter is omitted or zero, the page width is defaulted to 80. If the number of columns specified is not one of the values supported by the implementation, the next higher supported number of columns per page is assumed. If the number of columns specified exceeds the maximum number supported, the maximum number supported will be used.

DECSCPP does not cause the Active Position to move. However if the active position is beyond the width of the new page when the command is executed, the active position will be moved to the right edge of the page. DECSCPP does not cause the Right Margin to move. However if the right margin is beyond the width of the new page when the command is executed, the right margin will be moved to the right edge of the page. When changing from a 132 column to a 80 column page, the information in columns 1-80 is preserved. The information in columns 81-132 is cleared. When changing from an 80 column page to a 132 column page, the information in columns 1-80 is preserved.

Notes on DECSCPP:

1. The font used to display Page Memory may change when the number of columns on the page changes to better match the screen. Control of when the font changes may be provided as a Set-Up option.

2. The number of columns per page can also be changed through Column Mode (DECCOLM). The affect of DECSCPP is similar to DECCOLM except that DECSCPP does not clear page memory.

3. DECSCPP does not change the setting of DECLRMM.

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]
• active_position
• right_margin
• columns_per_page

Algorithm:

void set_columns_per_page(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
  line_t y;
  column_t x;
if ( (conformance_level == LEVEL_4) ||
     (level_3_extensions[WINDOWING]==TRUE) )
  {
  if (parv[0] <= 80)
    /* set columns per page to 80 */
    {
    for (y=1; y<MAX_NUM_LINES; y++)
      {
      for (x=81; x<MAX_NUM_COLUMNS; x++)
        display[y][x].code = EMPTY_CHARACTER;
      }
    if (active_position.column > 80) active_position.column = 80;
    if (right_margin > 80) right_margin = 80;
      /* optional font change */
      if (columns_per_page > 80) select_normal_font();
    columns_per_page = 80;
    }
  else
    /* set columns per page to 132 */
      /* optional font change */
      if (columns_per_page <= 80) select_condensed_font();
    columns_per_page = 132;
  }
}

Known Deviations: None

Set Lines Per Page — DECSLPP

Levels: 3X (Windowing), 4

Purpose: Set the number of lines per page in the Logical Display.

CSI     Pn      t
9/11    3/?     7/4

Description: This sequence sets the number of display lines per page according to the numeric parameter. If the parameter is omitted or zero, the page length is defaulted to 24. If the number of lines specified is not one of the values supported by the implementation, the next higher supported number of lines per page is assumed. If the number of lines specified exceeds the maximum number supported, the maximum number supported will be used.

DECSLPP does not cause Page Memory to be cleared, however, information contained in a larger page may appear in successive smaller pages, if the new height of the pages selected by the DECSLPP is too small to hold the information.

DECSLPP does not cause the scrolling regions to be reset, or the Active Position to move, except under the following circumstances: The scrolling margins may be reset to the extremes of the new Page Configuration if the current scrolling margin exceeds the physical limits of the new Page height; and, the Active Position will move to the same column in the maximum available line, if the Active Position exceeds the available number of lines in the new page size.

Conformance to Level 4 requires support for 3 pages of 24 lines.

State Affected:

• lines_per_page
• number_of_pages
• active_position
• top_margin
• bottom_margin

Algorithm:

void set_lines_per_page(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
if ( (conformance_level == LEVEL_4) ||
     (level_3_extensions[WINDOWING]==TRUE) )
  {
  if (parv[0] <= 24)
    {
    lines_per_page = 24;
    number_of_pages = 3;
    }
  else if (parv[0] == 25)
    {
    lines_per_page = 25;
    number_of_pages = 2;
    }
  else if (parv[0] <= 36)
    {
    lines_per_page = 36;
    number_of_pages = 2;
    }
  else
    {
    lines_per_page = 72;
    number_of_pages = 1;
    }

  if (active_position.line > lines_per_page)
    active_position.line = lines_per_page;
  if (active_position.page > number_of_pages)
    active_position.page  = number_of_pages;
  if (top_margin > lines_per_page)
    top_margin = 1;
  if (bottom_margin > lines_per_page)
    bottom_margin = lines_per_page;
  }
}

Known Deviations: None

Next Page — NP

Levels: 3x (Windowing), 4

Purpose: To move the Active Position ahead one or more pages in the Logical Display.

CSI     Pn      U
9/11    3/?     5/5

Description: This sequence causes the Active Position to move ahead a number of pages, specified by the parameter. If the parameter value is zero (the default) or one, the active position moves ahead 1 page. If the sequence calls for a page beyond the last page of display memory, the highest numbered page is used. NP moves the Active Position to the home position in the new page obeying Origin Mode.

Whether or not the new page is displayed depends upon the setting of DECPCCM.

State Affected:

• active_position

Algorithm:

void next_page(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
if ( (conformance_level == LEVEL_4) ||
     (level_3_extensions[WINDOWING]==TRUE) )
  {
  if (parv[0] == 0) parv[0] = 1;
  if ((active_position.page + parv[0]) <= number_of_pages)
    active_position.page += parv[0];
  else
    active_position.page = number_of_pages;
  if (origin_mode = DISPLACED)
    {
    active_position.line = top_margin;
    active_position.column = left_margin;
    }
  else
    {
    active_position.line = 1;
    active_position.column = 1;
    }
  }
}

Known Deviations: None

Preceding Page — PP

Levels: 3x (Windowing), 4

Purpose: To move the Active Position back one or more pages in the Logical Display.

CSI     Pn      V
9/11    3/?     5/6

Description: This sequence causes the active position to move back a number of pages, specified by the parameter. If the parameter value is zero (the default) or one, the active position moves back 1 page. If the sequence calls for a page before the first page of display memory, the first page is used. PP moves the active position to the home position in the new page obeying Origin Mode.

Whether or not the new page is displayed depends upon the setting of DECPCCM.

State Affected:

• active_position

Algorithm:

void preceding_page(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
if ( (conformance_level == LEVEL_4) ||
     (level_3_extensions[WINDOWING]==TRUE) )
  {
  if (parv[0] == 0) parv[0] = 1;
  if (active_position.page > parv[0])
    active_position.page -= parv[0];
  else
    active_position.page = 1;
  if (origin_mode = DISPLACED)
    {
    active_position.line = top_margin;
    active_position.column = left_margin;
    }
  else
    {
    active_position.line = 1;
    active_position.column = 1;
    }
  }
}

Known Deviations: None

Page Position Absolute — PPA

Levels: 3x (Windowing), 4

Purpose: To move the Active Position to the specified page in the Logical Display.

CSI     Pn      SP      P       (default Pn: 1)
9/11    3/?     2/0     5/0

Description: This sequence moves the Active Position to the corresponding line and column on the n-th page. If there are fewer than n pages in display memory, the highest numbered page is used.

Whether or not the new page is displayed depends upon the setting of DECPCCM.

State Affected:

• active_position

Algorithm:

void page_position_absolute(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
if ( (conformance_level == LEVEL_4) ||
     (level_3_extensions[WINDOWING]==TRUE) )
  {
  if (parv[0] == 0) parv[0] = 1;
  if (parv[0] <= number_of_pages)
    active_position.page = parv[0];
  else
    active_position.page = number_of_pages;
  }
}

Known Deviations: None

Page Position Relative — PPR

Levels: 3x (Windowing), 4

Purpose: To move the Active Position forward to the n-th succeding page in the Logical Display.

CSI     Pn      SP      Q       (default Pn: 1)
9/11    3/?     2/0     5/1

Description: This sequence moves the active position to the corresponding line and column of the n-th succeding page. If the sequence calls for a page beyond the last page of display memory, the highest numbered page is used.

Whether or not the new page is displayed depends upon the setting of DECPCCM.

State Affected:

• active_position

Algorithm:

void page_position_relative(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
if ( (conformance_level == LEVEL_4) ||
     (level_3_extensions[WINDOWING]==TRUE) )
  {
  if (parv[0] == 0) parv[0] = 1;
  if ((active_position.page + parv[0]) <= number_of_pages)
    active_position.page += parv[0];
  else
    active_position.page = number_of_pages;
  }
}

Known Deviations: None

Page Position Backward — PPB

Levels: 3x (Windowing), 4

Purpose: To move the Active Position back to the n-th preceding page in the Logical Display.

CSI     Pn      SP      R       (default Pn: 1)
9/11    3/?     2/0     5/2

Description: This sequence moves the active position to the corresponding line and column on the n-th preceding page. If the sequence calls for a page before the first page of display memory, the first page is used.

Whether or not the new page is displayed depends upon the setting of DECPCCM.

State Affected:

• active_position

Algorithm:

void page_position_backward(parv)
  short int parv[MAX_NUM_PARAMETERS];
{
if ( (conformance_level == LEVEL_4) ||
     (level_3_extensions[WINDOWING]==TRUE) )
  {
  if (parv[0] == 0) parv[0] = 1;
  if (active_position.page > parv[0])
    active_position.page -= parv[0];
  else
    active_position.page = 1;
  }
}

Known Deviations: None

Single-Width Line — DECSWL

Levels: 1-4

Purpose: Set the Line Rendition of the Active Line to single-⁠width

ESC     #       5
1/11    2/3     3/5

Description: Setting this attribute causes all characters indicated by the codes contained in the Active Line to be displayed in single-width rendition.

Notes:

1. Setting this attribute on a line which was previously double-width will cause the line length to be doubled.

2. Setting this attribute does not cause data contained in the Active Line to be lost.

State Affected:

• line_rendition[MAX_NUM_LINES]
• active_position

Algorithm:

void single_width_line()
{
  short int base;
base = (active_position.page-1) * lines_per_page;
line_rendition[active_position.line + base] = SINGLE_WIDTH;
}

Known Deviations: None

Double-Width Line — DECDWL

Levels: 1-4

Purpose: Set the Line Rendition of the Active Line to double-⁠width.

ESC     #       6
1/11    2/3     3/6

Description: Double-width characters are achieved by displaying the characters indicated by the codes contained in the Active Line in double-width rendition.

Notes:

1. Setting this attribute causes the length of the Active Line to be reduced by half.

2. Setting this attribute causes data which is beyond the end of the Active Line after execution of the control to be lost.

3. This control does not operate when DECLRMM (Left Right Margin Mode) is set.

State Affected:

• line_rendition[MAX_NUM_LINES]
• active_position
• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]

Algorithm:

void double_width_line()
{
  column_t x;
  short int base;
base = (active_position.page-1) * lines_per_page;
line_rendition[active_position.line + base] = DOUBLE_WIDTH;
if (active_position.column > end_of_line(active_position.line))
  active_position.column = end_of_line(active_position.line);
for (x=end_of_line(active_position.line)+1;
     x<=columns_per_page;
     x++)
  {
  display[active_position.line + base][x].code = EMPTY_CHARACTER;
  }
}

Known Deviations: None

Double-Height Line — DECDHLT,DECDHLB

Levels: 1-4

Purpose: Set the Line Rendition of the Active Line to double-⁠height top or double-height bottom.

ESC     #       3               top
1/11    2/3     3/3

ESC     #       4               bottom
1/11    2/3     3/4

Description: Double-height characters are achieved by setting the Line Rendition of adjacent lines to double-height top and double-height bottom. Setting double-height top causes the upper half of the characters indicated by the codes contained in the Active Line to be displayed in double-height and double-width rendition. Setting double-height bottom causes the lower half of the characters contained in the Active Line to be displayed in double-height and double-width rendition.

Notes:

1. Conforming software will not draw only the top or the bottom of double-height lines. When double-height lines are used, both the top and bottom must be displayed in adjacent line positions. Otherwise, the visual display of the line and the cursor symbol registration is UNDEFINED.

2. Since double-height also implies double-width, setting this attribute causes the length of the Active Line to be reduced by half.

3. Setting this attribute causes data which is beyond the end of the Active Line after execution of the control to be lost.

4. This control does not operate when DECLRMM (Left Right Margin Mode) is set.

State Affected:

• line_rendition[MAX_NUM_LINES]
• active_position
• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]

Algorithm:

void double_height_line_top()
{
  column_t x;
  short int base;
base = (active_position.page-1) * lines_per_page;
line_rendition[active_position.line + base] = DOUBLE_HEIGHT_TOP;
if (active_position.column > end_of_line(active_position.line))
  active_position.column = end_of_line(active_position.line);
for (x=end_of_line(active_position.line)+1;
     x<=columns_per_page;
     x++)
  {

  display[active_position.line + base][x].code = EMPTY_CHARACTER;
  }
}


void double_height_line_bottom()
{
  column_t x;
  short int base;
base = (active_position.page-1) * lines_per_page;
line_rendition[active_position.line + base] = DOUBLE_HEIGHT_TOP;
if (active_position.column > end_of_line(active_position.line))
  active_position.column = end_of_line(active_position.line);
for (x=end_of_line(active_position.line)+1;
     x<=columns_per_page;
     x++)
  {
  display[active_position.line + base][x].code = EMPTY_CHARACTER;
  }
}

Known Deviations: None

5.6.2.1 Normal Rendition

Normal rendition defines the rendering of characters in the physical display in its "natural" state, that is, where the character is rendered in the display foreground against a field of display background. Normal rendition is the absence of any special rendition of the character cell. (Note: Normal rendition of characters is dependent on the state of the Screen Mode, which is used to define the values of the foreground and background colors.)

5.6.2.2 Bold Rendition

Bold rendition of characters may be achieved either by emphasizing the display foreground without changing the background characteristics of the cell, or by intensifying the background color while holding the foreground value constant.

5.6.2.3 Blink Rendition

Blink rendition is achieved by alternating the stable rendition of a character with a different rendition at a fixed rate, with a duty cycle of approximately one second.

5.6.2.4 Underscore Rendition

Underscore rendition is achieved by the addition of a single horizontal bar extending the full width of the character field and rendered in the display foreground. The bar must be easily distinguishable from the underline character (5/15).

5.6.2.5 Reverse Rendition

Reverse rendition is achieved by using the current value of the foreground color as the cell background, and the current value of the background color as the foreground.

Select Graphic Rendition — SGR

Levels: 1-4

Purpose: Designate the graphic rendition to be applied to all subsequent characters entered into the display.

CSI     Ps ; ... ; Ps   m       default Ps: 0
9/11    Ps ; ... ; Ps   6/13

Description: The SGR control selects the graphic rendition (visual attribute) to be applied to all subsequent characters entered into the display. The parameter values indicate the combination of renditions to be selected as indicated in the following table (for both Level 1 and Level 2):

The following additional values are recognized in Level 2 operation. Although these values may be recognized when the terminal is operating as a Level 1 device, conforming software shall not rely on this feature.

Notes:

1. All other parameter values shall be ignored unless they are part of a well defined extension to the architecture.

2. Renditions may be selected in any combination, and will be rendered appropriately. Selecting additional renditions does not affect the setting of previously selected renditions (newly selected renditions will be combined with previously selected renditions) unless all renditions are turned off (parameter value zero (0)).

3. In no way does the selection of current rendition affect the rendition of characters already entered into the display.

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]

Algorithm:

void select_graphic_rendition(parc, parv)
  short int parc;
  short int parv[MAX_NUM_PARAMETERS];
{
  short int n;
if (parc == 0) parc = 1;
for (n=0; n<parc; n++)
  {
  switch(parv[n])
    {
    case 0:
      current_rendition.bold = FALSE;
      current_rendition.underscore = FALSE;
      current_rendition.blink = FALSE;
      current_rendition.reverse = FALSE;
      break;
    case 1:
      current_rendition.bold = TRUE;
      break;
    case 4:
      current_rendition.underscore = TRUE;
      break;
    case 5:
      current_rendition.blink = TRUE;
      break;
    case 7:
      current_rendition.reverse = TRUE;
      break;
    default:
      break;
    }
  if (conformance_level == LEVEL_2)
    {
    switch(parv[n])
      {
      case 22:
        current_rendition.bold = FALSE;
        break;
      case 24:
        current_rendition.underscore = FALSE;
        break;
      case 25:
        current_rendition.blink = FALSE;
        break;
      case 27:
        current_rendition.reverse = FALSE;
        break;
      default:
        break;
      }
    }
  }
}

Known Deviations: None

5.6.3.1 SGR Color Selection

A conforming device shall recognize parameter values 30-37 and 39 to the SELECT GRAPHIC RENDITION (SGR) control sequence to select the foreground color attribute and parameter values 40-47 and 49 to select the background color attribute, as specified in the table. The eight colors listed as factory defaults shall be available at a minimum. These colors are taken from the ANSI X3.64 standard.

A device may provide means, either under software or local control, to modify these colors and may provide means to save the modified colors in non-volatile memory.

5.6.3.2 Interaction With Other Visual Renditions

The foreground color and background color are maintained as part of the current_rendition. As new characters are written to the display, the current_rendition is used to update the attribute bits associated with each character in display memory.

Selecting the Reverse Rendition (SGR parameter 7) will, if the Reverse Rendition is not already set, be equivalent to invoking the current foreground color as the new background color, and the current background color as the new foreground color. Likewise, selecting the Positive Rendition (SGR parameter 27) will, if the Positive Rendition is not already set, be equivalent to invoking the current foreground color as the new background color, and the current background color as the new foreground color.

SGR parameters 30-37 and 39, the nine foreground color specifiers, will set the foreground color without regard to whether the Reverse Rendition is set. Likewise, SGR parameters 40-47 and 49, the nine background color specifiers, will set the background color without regard to whether the Reverse Rendition is set.

SGR parameter 0 (all renditions off) will reset the foreground and background color attributes to their defaults (equivalent to SGR parameters 39 and 49). SOFT TERMINAL RESET (DECSTR) will similarly cause the foreground and background color attributes to be reset.

When the Color Text Extension is present, the Bold Rendition (SGR parameter 1) should be distinguished by a heavier weight font (Guideline). It is preferable not to use a separate color (increased intensity) for bolding in order to keep it distinct from the other color text attributes.

Changing between normal and reverse screen mode (DECSCNM) will affect which attribute bits from display memory are used to render the text foreground and background color. It does not affect the current_rendition, or how the current_rendition is applied to the character attribute bits associated with each character in display memory.

The architecture does not specify the default text foreground or background colors. It is recommended however that normal screen mode correspond to lighter text on a darker background (not mandatory). The factory default for screen mode is device dependent. A device may provide means to save the screen mode in non-volatile memory so as to override the factory default at power-up.

5.6.3.3 Color Maps

A color map is a table that associates a binary value in display memory with a color that can be produced on the display. During display refresh, the active color map is used to translate color values from display memory to colors that appear on the screen. The size of the active color map cannot exceed 2**N entries where N is the number of bits used to represent a color in display memory (often the number of bit planes).

A device can have many color maps of which only one is active at time, or can assign color map entries from a single color map to different applications, limiting the size of each application's color map. Color maps can be read-only (fixed), or read-write (modifiable under software control).

Applications often model color selection as asking for a particular color (non-indexed, absolute color specification, read-⁠only), or asking for a particular color map entry (indexed color, read-write). When using indexed color, it is normal to allow the application to modify a color map entry causing all objects written with that color index to change color on the display.

Conforming devices may implement the ANSI SGR colors as indexed or non-indexed, and may allow selecting between these two models under local control.

5.6.3.4 Color Table Report (DECCTR)

A conforming device that supports the TSI and Color Text Extensions, and has a color table shall be capable of reporting the color table in the form of a DECCTR sequence as follows.

CSI  2   ;    Pu  $    u     (DECRQTSR Ps=2)
9/11 3/2 3/11 3/? 2/4  7/5

DCS 2   $    s  D...D ST     (DECTSR Ps=2)
9/0 3/2 2/4 7/3 D...D 9/12

DCS 2   $   p   D...D ST     (DECRSTS Ps=2)
9/0 3/2 2/4 7/0 D...D ST

5.6.3.5 Default Color Assignment (Guideline)

When indexed color is used, the following color map assignments are recommended to maximize compatibility among implementations when the colors are not specified explicitly (not mandatory). "Normal" text foreground and background refers to when Screen Mode is reset.

If more than four planes are supported, this series of 16 colors can be repeated as needed.

5.6.3.6 Color Interaction Among Modes And Data Syntaxes (Guideline)

ANSI Color Text, Sixels, and ReGIS can all support indexed color using a similar color model. A conforming device may share a single color map among these protocols so that changing a color definition in one protocol will affect the color map used by the other protocols. Support for the option of sharing the same color map is recommended, but not mandatory. Conforming software should not depend on cross protocol side effects if maximum portability is desired.

5.6.3.7 Alternative Text Rendition Mapping (Guideline)

Some previous terminals which do not support ANSI Color Text allowed other SGR parameters to select text colors.

For backward compatibility, the VT340 provides an alternative text rendition mapping mode selectable from Set-Up.

When alternative text rendition mapping is not selected, the reverse attribute is rendered by exchanging the text foreground and background colors.

A conforming device may provide an alternative text rendition mapping mode selectable in Set-Up, but this is not part of the Color Text Extension. The factory default behavior should be to treat bold and reverse graphic renditions independently of color selection (not mandatory).

CSI   Ps   )    {
9/11  3/?  2/9  7/11

Designate Character Set — SCS

Levels: 1-4

Purpose: Designate the graphic character sets.

ESC  <G-Set designator>  <Character set designator>

The G-Set designators are:

• 94 character sets
  • G0 ( 2/8
  • G1 ) 2/9
  • G2 * 2/10
  • G3 + 2/11
• 96 character sets
  • G1 - 2/13
  • G2 . 2/14
  • G3 / 2/15

The Character set designators are:

• ASCII_G B 4/2
• LINE_DRAWING_G 0 3/0
• DEC_SUPPLEMENTAL_G %5 2/5 3/5
• ISO_LATIN1_SUPPLEMENTAL_G A 4/1
• UPSS_G < 3/12
• DRCS_G I I F 2/? 2/? ?/?
• TCS_G >
• JIS Roman J 4/10
• JIS Katakana I 4/9
• NRCS
  • British A
  • Dutch 4 (discontinued in L3)
  • Finnish 5 or C
  • French R
  • French Canadian Q
  • German K
  • Italian Y
  • Norwegian/Danish E or 6
  • Portuguese %6
  • Spanish Z
  • Swedish 7 or H
  • Swiss =

For example,

• ESC ( B designates ASCII_G to G0
• ESC ) 0 designates Line Drawing to G1
• ESC * < designates the UPSS to G2

Description: The character set designating escape sequences provide the means of selecting the G0, G1, G2, and G3 character sets, which can be invoked into the left (GL) and right (GR) sides of the In Use Table. (For a complete description of the G-sets and the In Use Table, see the section "Code Extension Layer".)

Notes:

1. In Level 1 operation character sets can only be designated into G0 and G1, with G2 and G3 containing the ASCII character set by default.

2. Conforming software will not change the default designations of the G0 and G2 character sets. The G1 and G3 sets will be used when it is desired to designate alternate character sets. Furthermore, conforming software will not designate ASCII_G to either G2 or G3, and will not designate Supplemental_G to either G0 or G1.

3. Designating a character set which is invoked into the In Use Table at the time the control is executed causes the In Use Table to be changed to reflect the change to the designated set.

4. As a Level 1 extension, the UK (United Kingdom) Character Set may be provided, and designated with the sequence ESC I A (1/11 I 4/1). If this extension is supported, it may also be possible to locally select the UK set to replace ASCII as the default 7-bit set. In this case, the UK set will be used in all instances in which ASCII is employed throughout the Video Systems Reference Manual when the terminal is in Level 1 operation.

5. On traditional video terminals with the NRCS extension, it is permissable to only recognize the one NRC set corresponding to the keyboard dialect at a time. Workstation terminal emulators may extend the character set table to recognize all NRC sets regardless of the current keyboard dialect (not mandatory).

State Affected:

• designated_graphic_sets[4]
• in_use_table

Algorithm:

/***************
 *
 * Initialize the character set table
 *   This procedure should be called on power-up or
 *   reset to initialize the character set table
 *   with the appropriate designating sequences.
 *
 **************/
void intialize_character_set_table()
{
char_set_table[TABLE_ASCII].name = ASCII_G;
char_set_table[TABLE_ASCII].first_intermediate = 0;
char_set_table[TABLE_ASCII].second_intermediate = 0;
char_set_table[TABLE_ASCII].final = 'B';

char_set_table[TABLE_LINE_DRAWING].name = LINE_DRAWING_G;
char_set_table[TABLE_LINE_DRAWING].first_intermediate = 0;
char_set_table[TABLE_LINE_DRAWING].second_intermediate = 0;
char_set_table[TABLE_LINE_DRAWING].final = '0';

if (conformance_level >= LEVEL_2)
  {
  char_set_table[TABLE_DEC_SUPP].name = DEC_SUPPLEMENTAL_G;
  char_set_table[TABLE_DEC_SUPP].first_intermediate = '%';
  char_set_table[TABLE_DEC_SUPP].second_intermediate = 0;
  char_set_table[TABLE_DEC_SUPP].final = '5';

  if (level_2_extensions[DRCS_EXT]==TRUE)
    {
    char_set_table[TABLE_DRCS].name = DRCS_G;
    char_set_table[TABLE_DRCS].first_intermediate = 0;
    char_set_table[TABLE_DRCS].second_intermediate = 0;
    char_set_table[TABLE_DRCS].final = 0;
    }
  if (level_2_extensions[NRCS_EXT]==TRUE)
    {
    /*
       This entry is initialized to correspond
       with the keyboard dialect whenever it
       is changed in Set-Up.
     */
    char_set_table[TABLE_NRCS].name = NRCS_G;
    char_set_table[TABLE_NRCS].first_intermediate = 0;
    char_set_table[TABLE_NRCS].second_intermediate = 0;
    char_set_table[TABLE_NRCS].final = 0;
    }
  }
if ((conformance_level >= LEVEL_3) ||
    (level_2_extensions[EIGHT_BIT_IA]==TRUE))
  {
  char_set_table[TABLE_LATIN1].name = ISO_LATIN1_SUPPLEMENTAL_G;
  char_set_table[TABLE_LATIN1].first_intermediate = 0;
  char_set_table[TABLE_LATIN1].second_intermediate = 0;
  char_set_table[TABLE_LATIN1].final = 'A';

  char_set_table[TABLE_UPSS].name = UPSS_G;
  char_set_table[TABLE_UPSS].first_intermediate = 0;
  char_set_table[TABLE_UPSS].second_intermediate = 0;
  char_set_table[TABLE_UPSS].final = '<';
  }
if (level_3_extensions[TCS]==TRUE)
  {
  char_set_table[TABLE_TCS].name = TCS_G;
  char_set_table[TABLE_TCS].first_intermediate = 0;
  char_set_table[TABLE_TCS].second_intermediate = 0;
  char_set_table[TABLE_TCS].final = '>';
  }
}





void designate_character_set(parc, parv)
  /* parc and parv contain the count and values
     of the indermediate characters of the
     designating sequence */
  short int parc;
  short int parv[MAX_NUM_INTERMEDIATES];
{
  short int n;
  short int gset_number;
  short int set_size;
  boolean_t compare_designator();  /* function declaration */
/*.....................*/
/* find which set we're designating */
switch (parv[0])
  {
  case ')':  /* 2/8  designate 94 into G0 */
    gset_number = 0;
    set_size = 94;
    break;
  case '(':  /* 2/9  designate 94 into G1 */
    gset_number = 1;
    set_size = 94;
    break;
  case '*':  /* 2/10 designate 94 into G2 */
    gset_number = 2;
    set_size = 94;
    break;
  case '+':  /* 2/11 designate 94 into G3 */
    gset_number = 3;
    set_size = 94;
    break;
  case '-':  /* 2/13 designate 96 into G1 */
    gset_number = 1;
    set_size = 96;
    break;
  case '.':  /* 2/14 designate 96 into G2 */
    gset_number = 2;
    set_size = 96;
    break;
  case '/':  /* 2/15 designate 96 into G3 */
    gset_number = 3;
    set_size = 96;
    break;
  }

/* look for the designator in the table */
/*
   Note that because the DRCS designator is processed last,
   it will replace an installed set if the designator is
   identical.
*/
for (n=0; n<MAX_NUM_CHAR_SETS; n++)
  {
  if ( compare_designator(parc, parv, n) )
    {
    designated_graphic_sets[gset_number] =
      char_set_table[n].name;
    }
  }

/* update the in_use_table with
   the latest designations (if any)
   for the invoked gsets */
in_use_table.gl =
  designated_graphic_sets[in_use_table.invoked_gl];
if (conformance_level >= LEVEL_2)
  {
  in_use_table.gr =
    designated_graphic_sets[in_use_table.invoked_gr];
  }
/* perform hardware specific actions needed
   to update the character set displayed */
}  /* end procedure designate_character_set */


/*
 * compare sequence designator to table entry n
 */
boolean_t compare_designator(parc, parv, n)
  short int parc;  /* number of sequence characters */
  short int parv[MAX_NUM_INTERMEDIATES];
  short int n;     /* char set table entry */
{
  boolean_t status;
status = TRUE;
if (char_set_table[n].final != parv[parc-1])
  status = FALSE;
else
  {
  if (parc > 2)
    {
    if (char_set_table[n].first_intermediate != parv[1])
      status = FALSE;
    else
      {
      if (parc >= 3)
        if (char_set_table[n].second_intermediate != parv[2])
          status = FALSE;
      }
    }
  }
return(status);
}

Known Deviations: None

Assign User-Preference Supplemental Set — DECAUPSS

Levels: 2x (8-bit Interface Architecture), 3-4

Purpose: To assign a user preferred supplemental set

DCS  Ps  !    u    Dscs  ST
9/0      2/1  7/5        9/12

Description: This control string assigns a character set to be the User-Preference Supplemental Set (UPSS). The User-Preference Supplemental Set serves the following functions:

1. It acts as the default supplemental set for reception. On soft terminal reset, the UPSS is designated as G2.

2. It acts as the keyboard supplemental set, that is, it determines which supplemental characters can be generated from the keyboard (including valid compose sequences).

3. It provides a level of indirection for application software. The UPSS can be explicitly designated without needing to know the actual character set assigned.

Currently DEC Supplemental and ISO Latin-1 supplemental may be used as the UPSS. The default User-Preference Supplemental Set is determined through a Set-Up feature. The value of Ps and Dscs denote which set from the terminal's repertory of character sets is to be the User-Preference Supplemental Set.

Ps selects between 94 and 96 character sets (Ps = 0 selets a 94 character set). Dscs is the intermediate and final characters of the SCS escape sequence used to explicitly designated that character set. For example a value of "% 5" for Dscs indicates that the DEC Supplemental character set is the User-Preference Supplemental set. See the SCS command for more information on the designating intermediate and final characters. Attempts to assign an invalid supplemental set will be ignored.

Notes on DECAUPSS:

1. The DRCS can be used as the UPSS by naming it as DEC Supplemental or ISO Latin-1 supplemental.

2. Assigning a new UPSS will immediately update the In-Use table if the UPSS is currently designated and invoked.

3. This sequence is sent from the terminal to the host in response to a DECRQUPSS request.

State Affected:

• upss /* defined in code extension layer */

Algorithm:

void assign_user_preference_set(parv, string)
  short int parv[MAX_NUM_PARAMETERS];
  char string[];
{
if ((conformance_level >= LEVEL_3) ||
    (level_2_extensions[EIGHT_BIT_IA] == TRUE))
  {
  /* update upss state in Code Extension Layer */
  if ((parv[0] = 0) && (strcmp(string, "%5") == 0))
    {
    /* size is 94 characters */
    upss = DEC_SUPPLEMENTAL_G;
    }
  else if ((parv[0] = 1) && (strcmp(string, "A") == 0))
    {
    /* size is 96 characters */
    upss = ISO_LATIN1_SUPPLEMENTAL_G;
    }

  /* update in use table */
  if (in_use_table.gl == UPSS_G)
    {
    ; /* perform hardware dependent actions as needed */
    }
  if (in_use_table.gr == UPSS_G)
    {
    ; /* perform hardware dependent actions as needed */
    }
  }
}

Known Deviations: None

Request User-Preference Supplemental Set — DECRQUPSS

Levels: 2x (8-bit Interface Architecture), 3-4

Purpose: To request the user preferred supplemental set

CSI   &    u
9/11  2/6  7/5

Description: Upon receipt of this sequence, the terminal will return a DECAUPSS sequence which specifies which coded character set is assigned to be the User-Preference Supplemental Set.

State Affected: none

Algorithm:

void request_user_preference_set()
{
if ((conformance_level >= LEVEL_3) ||
    (level_2_extensions[EIGHT_BIT_IA] == TRUE))
  {
  send_char(0x90, host_port);  /* DCS */
  if (upss = DEC_SUPPLEMENTAL_G)
    {
    send_int(0, host_port);
    send_string("!u%5", host_port);
    }
  else if (upss = ISO_LATIN1_SUPPLEMENTAL_G)
    {
    send_int(1, host_port);
    send_string("!uA", host_port);
    }
  send_char(0x9C, host_port);  /* ST */
  }
}

Known Deviations: None

Set/Reset Character Set Mode — DECNRCM

Levels: 1x, 2x, 3x, 4x (NRCS Extension)

Purpose: To select 8-bit Multinational Characters, or 7-bit NRCS Characters for transmission (keyboard) and reception (display).

CSI ? 42 h   (7-bit NRCS Characters)

CSI ? 42 l   (8-bit Multinational Characters)

Description: This parameter is applicaple to the Set Mode and Reset Mode control sequence. When 8-bit Multinational Characters is selected (factory default), the terminal uses ASCII in GL and either DEC Supplemental or ISO Latin-1 Supplemental in GR (depending on the UPSS). When 7-bit NRCS Characters is selected, a 7-bit National Replacement Character set is used for transmission and reception in GL (GR is not used). The NRCS used is determined by the Keyboard Dialect chosen in Set-Up (see "Keyboard Processing", DEC STD 70-6).

Notes on DECNRCM:

1. Changing this mode has the side effect of re-initializing the designated and invoked character sets to their default state (the state at power-on or reset). If 7-bit NRCS Characters is selected, a 7-bit NRC Set may replace U.S. ASCII in the default designations.

2. 8-bit Characters are temporarily disabled when in Level 1 (VT100 mode), or a 7-bit host line environment is selected. The DECNRCM sequence will still be recognized, but in the case of the reset sequence, 8-bit characters will remain disabled until the restrictive conditions are removed.

3. This sequence is ignored when the North American or Dutch Keyboard Dialect is selected. These keyboard dialects use U.S. ASCII as their 7-bit set, so there is no need to disable the multinational set (which includes U.S. ASCII as its left half) to access 7-bit NRC characters. U.S. ASCII may be considered the NRC set for North America.

State Affected:

• character_set_mode
• r_character_set_mode /* used to keep track of character set mode when a restrictive condition (7-bit Host Line, or VT100 mode) is in effect */
• in_use_table
• designated_graphic_sets[4]

Algorithm:

void set_character_set_mode()
{
if (level_1_extensions[NRCS_EXT]==TRUE)
  {
  character_set_mode = SEVEN_BIT_NATIONAL;
  /* keep track of mode if there are restrictions in effect */
  r_character_set_mode = SEVEN_BIT_NATIONAL;
  if (keyboard_usage_mode == TYPEWRITER)
    {
    in_use_table.gl = nrcs_list[keyboard_dialect];
    in_use_table.gr = nrcs_list[keyboard_dialect];
    in_use_table.invoked_gl = G0;
    in_use_table.invoked_gr = G2;
    designated_graphic_sets[0] = nrcs_list[keyboard_dialect];
    designated_graphic_sets[1] = nrcs_list[keyboard_dialect];
    designated_graphic_sets[2] = nrcs_list[keyboard_dialect];
    designated_graphic_sets[3] = nrcs_list[keyboard_dialect];
    }
  else    /* keyboard usage mode is Data Processing */
    {
    in_use_table.gl = ASCII_G;
    in_use_table.gr = ASCII_G;
    in_use_table.invoked_gl = G0;
    in_use_table.invoked_gr = G2;
    designated_graphic_sets[0] = ASCII_G;
    designated_graphic_sets[1] = ASCII_G;
    designated_graphic_sets[2] = ASCII_G;
    designated_graphic_sets[3] = ASCII_G;
    }
  }
}


void reset_character_set_mode()
{
if (level_1_extensions[NRCS_EXT]==TRUE)
  {
  /* keep track of mode if there are restrictions in effect */
  r_character_set_mode = EIGHT_BIT_MULTINATIONAL;
  /* ignore if 7-bit host line or VT100 mode */
  if ((host_port_environment != SEVEN_BIT) &&
      (conformance_level != LEVEL_1))
    {
    character_set_mode = EIGHT_BIT_MULTINATIONAL;
    in_use_table.gl = ASCII_G;
    in_use_table.gr = UPSS_G;
    in_use_table.invoked_gl = G0;
    in_use_table.invoked_gr = G2;
    designated_graphic_sets[0] = ASCII_G;
    designated_graphic_sets[1] = ASCII_G;
    designated_graphic_sets[2] = UPSS_G;
    designated_graphic_sets[3] = UPSS_G;
    }
  }
}

Known Deviations: None

Substitute — SUB

Levels: 1-4

Purpose: Place a reversed question mark symbol in the display.

SUB
1/10

Description: The SUB control is used to indicate the presence of characters in the data stream for which there is no graphic representation. This control is processed by placing a reversed question mark in the display at the Active Position.

Notes:

1. The character to be displayed in cases where the reversed question mark cannot be used is a "half-tone blotch", which is rendered by filling the entire character cell in the display with a cross-hatched pattern.

2. Receipt of the Substitute character within an escape or control sequence causes the sequence in progress to be aborted and the Substitute control function to be executed instead (that is, the reversed question mark symbol will be displayed). (See the section "Code Extension Layer" for a complete description of the handling of control characters within escape and control sequences.)

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]
• active_position

Algorithm:

void substitute()
{
short int sub = 0x1A;
/*..........*/

/* place a reversed question mark in the display */
insert_or_replace_character(&sub);
}

Known Deviations:

Most existing terminals (VT100, VT101, VT102, VT125, VT131, VT132) display the blotch character instead of the reversed question mark.

5.10.1.1 ANSI Specified Modes:

5.10.1.2 DEC Private Modes:

If the first character in the parameter string is 3/15 (?), the parameters are interpreted as DEC private parameters, according to the following table.

Any other parameter values are ignored.

5.10.1.3 Modes That Cannot Be Changed

The following modes which are specified in the ANSI X3.64-1979 standard may be considered to be permanently set, permanently reset, or not applicable, as noted. Refer to that standard for further information concerning these modes.

Set/Reset Send Receive Mode — SRM

Levels: 1-4

Purpose: To turn the local echo feature ON or OFF

CSI 12 h        (local echo off, default)

CSI 12 l        (local echo on)

Description: SRM is a parameter applicable to the Set Mode and Reset Mode control sequences. The reset state causes local echo to be ON. The set state causes local echo to be OFF.

State Affected:

• send_receive_mode /* See Keyboard Processing */
• r_send_receive_mode

Algorithm:

void set_send_receive_mode()
{
send_receive_mode = ECHO_OFF;
/* remember state in case there are restrictions */
r_send_receive_mode = ECHO_OFF;
}


void reset_send_receive_mode()
{
/* remember state in case there are restrictions */
r_send_receive_mode = ECHO_ON;
if ((printer_controller_mode != PRINTER_CONTROLLER_ON) &&
    (line_local_mode != LOCAL))
  send_receive_mode = ECHO_ON;
}

Known Deviations: None

5.11.1.1 Normal Character Attribute

The Normal character attribute defines the non-visible attributes in the physical display in its "natural" state, that is, where the character behaves with no special non-visible attributes.

5.11.1.2 Selectively Erasable Character Attribute

One logical attribute may be applied to characters as a Level 2 or higher extension. This attribute is referred to as "Selectively Erasable Character". When this extension is provided, the terminal will recognize two forms of the commands Erase_In_Line and Erase_In_Display: one in which all characters in the given extent are erased, regardless of their logical attributes, and another in which all character in the given extent which have been assigned the Selectively Erasable Character attribute are turned into Space characters (2/0). (See the Select Character Attribute, Erase In Line, and Erase In Display control functions for a complete description of this feature).

Select Character Attribute — DECSCA

Levels: 2x, 3x, 4x (Selective Erase)

Purpose: Designate the character attribute(s) to be applied to all subsequent characters entered into the display.

CSI     Ps ; ... ; Ps   "   q       default Ps: 0
9/11    Ps ; ... ; Ps   2/2 7/1

Description: The DECSCA control selects the character attribute (logical attribute) to be applied to all subsequent characters entered into the display. The parameter values indicate the combination of attributes to be selected as indicated in the following table:

Notes:

1. Character attribute parameter values are assigned in pairs. The lower (odd) value sets the attribute to the on state and the higher (even) value resets the attribute to the off state (same as normal or when all attributes are turned off (value 0).

2. All other parameter values will be ignored.

3. Attributes may be selected in any combination, and will be rendered appropriately. Selecting additional attributes does not affect the setting of previously selected attributes (newly selected attributes will be combined with previously selected attributes) unless all attributes are turned off (parameter value zero (0)).

4. In no way does the selection of attributes affect the rendition (SGR) or attributes (DECSCA) of characters already entered into the display.

5. This control is ignored unless the Level 2 or higher extension for Selectively Erasable Characters is supported. The Selectively Erasable Character attribute affects the execution of the controls Selective Erase In Line (DECSEL) and Selective Erase In Display (DECSED).

State Affected:

• display[MAX_NUM_LINES][MAX_NUM_COLUMNS]

Algorithm:

void select_character_attribute(parc, parv)
  short int parc;
  short int parv[MAX_NUM_PARAMETERS];
{
  short int n;
/*................*/
if (conformance_level >= 2)
  {
  if (parc == 0) parc = 1;
  for (n=0; n<parc; n++)
    {
    switch(parv[n])
      {
      case 0:
        current_attribute.selective_erase = TRUE;
        break;
      case 1:
        current_attribute.selective_erase = FALSE;
        break;
      case 2:
        current_attribute.selective_erase = TRUE;
        break;
      }
    }
  }
} /* end select_character_attribute() */

Known Deviations: None

Copy Rectangular Area — DECCRA

Level: 4

Purpose: To copy a rectangular array of characters from one part of a logical display page to another.

CSI   Pts; Pls; Pbs; Prs; Pps; Ptd; Pld; Ppd  $    v
9/11  Pts; Pls; Pbs; Prs; Pps; Ptd; Pld; Ppd  2/4  7/6

Description: When this control is received, the terminal copies the character values and attributes in the specified rectangular area of character positions defined by Pts, Pls, Pbs, and Prs on the specified page Pps, to the area specified by the coordinate Ptd, Pld on the specified page Ppd. Pts, Pbs, and Ptd are line numbers. Pls, Prs, and Pld are column numbers. Pps and Ppd are page numbers. The character positions (Pts, Pls) and (Pbs, Prs) define the rectangular area that is to be copied from page Pps.

The coordinates of the rectangular area are affected by the setting of Origin Mode. This control is not otherwise affected by the margins.

If the rectangular area contains both single and double width lines, the area copied FROM may not appear rectangular on the display. For example if Pl=5 and Pr=10, then characters 5 through 10 from all lines within the rectangular area will be copied whether they are single width or double width characters. Text copied to the destination area take on the line attributes of that area.

Pts must be less or equal to Pbs, and Pls must be less than or equal to Prs, otherwise the entire control function is ignored. Default values are Pts = 1, Pls = 1, Pbs = last-line-of-page, Prs = last-column-of-page, Pps = 1, Ptd = 1, Pld = 1, and Ppd = 1. If a value exceeds the width or height of the active page, it is treated as the width or height of the active page. If a page value exceeds the number of pages available in the current Page Configuration, it is treated as the last page in the current configuration.

If the destination rectangle specified is partially off of the Page, clipping of information will occur; only information which will appear in valid character positions in the page will be copied.

The Active Position does not change.

Fill Rectangular Area — DECFRA

Level: 4

Purpose: To fill a group of adjacent character positions defined by a rectangular area.

CSI   Pch ; Pt ; Pl ; Pb ; Pr  $    x
9/11  Pch ; Pt ; Pl ; Pb ; Pr  2/4  7/8

Description: When this control is received, the terminal fills the rectangular area of character positions defined by Pt, Pl, Pb, and Pr, replacing both the character and the rendition present in those character positions with the character defined by the decimal value of Pch and the current renditions set through the SGR command.

The Pch parameter may be a decimal value from 32 to 126, or from 160 to 255. The decimal value refers to the character in the current GL and GR "in-use" character table, which is used to fill the specified rectangular area. If the value of Pch is not in the above range, the command is ignored.

Pt and Pb are line numbers, and Pl and Pr are column numbers. The character positions (Pt, Pl) and (Pb, Pr) define the rectangular area.

The coordinates of the rectangular area are affected by the setting of Origin Mode. This control is not otherwise affected by the margins.

Pt must be less or equal to Pb, and Pl must be less than or equal to Pr, otherwise the entire control function is ignored. Default values are Pch = 32, Pt = 1, Pb = last-line-of-page, Pl = 1, and Pr = last-column-of-page. If a value exceeds the width or height of the active page, it is treated as the width or height of the active page.

Notes on DECFRA:

1. If the rectangular area contains both single and double width lines, the area affected may not appear rectangular on the display. For example if Pl=5 and Pr=10, then all lines within the rectangular area, whether single or double width, will have character positions 5 through 10 affected.

2. DECFRA does not change any line attributes. Double height or double width characters will be filled into positions on lines containing those attributes. The Active Position does not move.

Erase Rectangular Area — DECERA

Level: 4

Purpose: To erase a group of adjacent characters defined by a rectangular area.

CSI   Pt ; Pl ; Pb ; Pr  $    z
9/11  Pt ; Pl ; Pb ; Pr  2/4  7/10

Description: When this control is received, the terminal erases the rectangular area of character positions defined by Pt, Pl, Pb, and Pr, clearing all character attributes. Line attributes are not changed. When an area is erased, all characters are replaced with the Space character (2/0). Any unoccupied character positions remain unoccupied. The Active Position does not move.

Pt and Pb are line numbers, and Pl and Pr are column numbers. The character positions (Pt, Pl) and (Pb, Pr) define the rectangular area.

The coordinates of the rectangular area are affected by the setting of Origin Mode. This control is not otherwise affected by the margins.

Pt must be less or equal to Pb, and Pl must be less than or equal to Pr, otherwise the entire control function is ignored. Default values are Pt = 1, Pb = last-line-of-page, Pl = 1, and Pr = last-⁠column-of-page. If a value exceeds the width or height of the active page, it is treated as the width or height of the active page.

Notes on DECERA:

1. If the rectangular area contains both single and double width lines, the area affected may not appear rectangular on the display. For example if Pl=5 and Pr=10, then all lines within the rectangular area, whether single or double width, will have character positions 5 through 10 affected.

Selective Erase Rectangular Area — DECSERA

Level: 4

Purpose: To erase a group of unprotected characters defined by a rectangular area.

CSI   Pt ; Pl ; Pb ; Pr  $    {
9/11  Pt ; Pl ; Pb ; Pr  2/4  7/11

Description: This control function erases unprotected characters within the rectangular area of character positions defined by Pt, Pl, Pb, and Pr. Unprotected characters are those with the "Selective Erase" character attribute (see DECSCA). When a character is erased, it is replaced with the Space character (2/0). Unoccupied character positions are not affected. This sequence does not change or clear any video character attributes (SGR or DECSCA), video line attributes, or the selection attribute. The active position does not move.

Pt and Pb are line numbers, and Pl and Pr are column numbers. The character positions (Pt, Pl) and (Pb, Pr) define the rectangular area.

The coordinates of the rectangular area are affected by the setting of Origin Mode. This control is not otherwise affected by the margins.

Pt must be less or equal to Pb, and Pl must be less than or equal to Pr, otherwise the entire control function is ignored. Default values are Pt = 1, Pb = last-line-of-page, Pl = 1, and Pr = last-⁠column-of-page. If a value exceeds the width or height of the active page, it is treated as the width or height of the active page.

Notes on DECSERA:

1. If the rectangular area contains both single and double width lines, the area affected may not appear rectangular on the display. For example if Pl=5 and Pr=10, then all lines within the rectangular area, whether single or double width, will have character positions 5 through 10 affected.

Change Attributes Rectangular Area — DECCARA

Level: 4

Purpose: To change the character rendition of a group of adjacent characters without having to re-write them.

CSI   Pt ; Pl ; Pb ; Pr ; Ps1 ; Ps2...Psn  $    r
9/11  Pt ; Pl ; Pb ; Pr ; Ps1 ; Ps2...Psn  2/4  7/2

Description: This sequence changes the video attributes (bold, blink, underline, and reverse) for all of the character positions in a rectangular area without altering any characters in those positions. The active position does not move.

The area of the page which is affected is indicated by the first 4 parameters. Pt and Pb are line numbers; Pl and Pr are column numbers. The character positions (Pt, Pl) and (Pb, Pr) define the top-left and bottom-right corners of the rectangular area. Pt must be less than or equal to Pb, and Pl must be less than or equal to Pr. Default values are Pt = 1, Pb = last-line-of-page, Pl = 1, and Pr = last-column-of-page. If a value exceeds the width or height of the active page, it is treated as the width or height of the active page.

The coordinates of the rectangular area are affected by the current setting of Origin Mode. This control is not otherwise affected by the margins.

The character positions affected depend on the current setting of DECSACE (STREAM or RECTANGLE). See DECSACE for details.

The video attribute(s) that the character positions are set to is indicated by one or more subsequent selective parameters. These parameters correspond to the parameters of the Set Graphic Rendition control function (SGR):

All other parameter values shall be ignored unless they are part of a well defined extension to the architecture (such as Color Text). When multiple parameters are used, they are cumulative, as if several DECCARA control functions were received and executed in sequence.

The default for the video attribute parameters, if no valid subsequent parameter is received, is 0, which will clear all video attributes in the specified area. This command does not change the current graphic rendition.

Notes on DECCARA:

1. If the rectangular area contains both single and double width lines, the area affected may not appear rectangular on the display. For example if Pl=5 and Pr=10, then all lines within the rectangular area, whether single or double width, will have character positions 5 through 10 affected.

Reverse Attributes Rectangular Area — DECRARA

Level: 4

Purpose: To reverse character attributes of a group of adjacent characters without having to re-write them.

CSI   Pt ; Pl ; Pb ; Pr ; Ps1 ; Ps2...Psn  $    t
9/11  Pt ; Pl ; Pb ; Pr ; Ps1 ; Ps2...Psn  2/4  7/4

Description: This sequence reverses one or more video attributes (bold, blink, underline, reverse) for all of the character positions in a rectangular area without altering any characters in those positions. The active position does not move. To reverse the attribute bit within the specified range means to set the specified attribute bits if it was not previously set, and reset the bit(s) if it was already set.

The area of the page which is affected is indicated by the first 4 parameters. Pt and Pb are line numbers; Pl and Pr are column numbers. The character positions (Pt, Pl) and (Pb, Pr) define the top-left and bottom-right corners of the rectangular area.

The coordinates of the rectangular area are affected by the setting of Origin Mode. This control is not otherwise affected by the margins.

The character positions affected depend on the current setting of DECSACE (STREAM or RECTANGLE). See DECSACE for more details.

Pt must be less or equal to Pb, and Pl must be less than or equal to Pr, otherwise the entire control function is ignored. Default values are Pt = 1, Pb = last-line-of-page, Pl = 1, and Pr = last-⁠column-of-page. If a value exceeds the width or height of the active page, it is treated as the width or height of the active page.

The video attribute(s) to be reversed are in the affected area are indicated by one or more subsequent parameters. These parameters are similar to the parameters of the Set Graphic Rendition control function (SGR):

All other parameter values shall be ignored unless they are part of a well defined extension to the architecture. Note if the Color Text Extension is present, the color text SGR values are ignored since the "reverse" of a color is not defined by the extension.

When multiple parameters are used, they are cumulative, as if several DECRARA control functions were received and executed in sequence.

There is no default for the video attribute parameters, if no valid subsequent parameter is received, the command is ignored.

This sequence does not change the current graphic rendition (see SGR).

Notes on DECRARA:

1. If the rectangular area contains both single and double width lines, the area affected may not appear rectangular on the display. For example if Pl=5 and Pr=10, then all lines within the rectangular area, whether single or double width, will have character positions 5 through 10 affected.

Select Attribute Change Extent — DECSACE

Level: 4

Purpose: To specify what character positions are affected by DECCARA and DECRARA control functions (STREAM or RECTANGLE)

CSI   Ps  *     x
9/11  Ps  2/10  7/8

• Ps = 0 stream of character positions are affected (default)
• Ps = 1 stream of character positions are affected
• Ps = 2 rectangular area of character positions are affected

Description: This control function is used to specify what character positions are affected by the DECCARA and DECRARA control functions.

When Ps = 0 or 1, DECCARA and DECRARA affects the stream of character positions beginning with the first character position specified in the command, and ending with the second character position specified. The following diagram shows an example of these character positions. The two asterisks represent the character positions specified in the DECCARA or DECRARA control function. The "U"'s represent unoccupied character positions. These unoccupied positions are not affected by DECCARA or DECRARA when in this mode.

+-----------------+
|                 |
|  *##############|
|########UUUUUUUUU|      Ps = 0
|#################|
|###########*     |
|                 |
+-----------------+

When Ps = 2 DECCARA and DECRARA affects all character positions within a rectangular area, the top-left and bottom right corners of which are specified in the control function. The following diagram shows an example of these character positions. The two asterisks represent the character positions specified in the DECCARA or DECRARA control function. The "U"'s represent unoccupied character positions. When DECCARA or DECRARA is executed, these character positions are changed to blanks and are affected.

+-----------------+
|                 |
|  *#########     |
|  ##########UUUUU|      Ps = 2
|  ##########     |
|  #########*     |
|                 |
+-----------------+

In both cases the specified character positions (marked by asterisks) are also affected.

Request Checksum Of Rectangular Area — DECRQCRA

Level: 4

Purpose: To cause the terminal to compute and report the checksum of a rectangular area, allowing applications to insure it has not been changed.

CSI   Pid ; Pp ; Pt ; Pl ; Pb ; Pr  *     y
9/11  Pid ; Pp ; Pt ; Pl ; Pb ; Pr  2/10  7/9

Description: Upon receipt of a DECRQCRA by the device, a checksum of the indicated rectangular area of the indicated page will be generated and reported to the host in a Checksum Report (DECCKSR).

Pid is an arbitrary numeric label provided by the application to identify the checksum request. It will be provided in the DECCKSR response from the device. This label serves to differentiate between multiple checksum reports if necessary.

Pp is the page number where the rectangular area of interest is located. If Pp is 0 or omitted, subsequent parameters are ignored and a checksum for all page memory will be reported. If Pp is higher than the total number of pages available in the device, the highest numbered page is used.

The final four parameters indicate the top, left (Pt, Pl) and bottom, right (Pb, Pr) coordintate of the rectangular area on page Pp of which the checksum is to be calculated. The coordinates of the rectangular area are affected by the setting of Origin Mode (DECOM). Pt must be less than or equal to Pb, and Pl must be less than or equal to Pr or the sequence is ignored.

Default values are: Pt = 1; Pb = last-line-of-page; Pl = 1; and Pr = last-column-of-page. If the final four parameters are unspecified, a checksum of page Pp is generated.

Memory Checksum Device Status Report — DSR

Level: 4

Purpose: To request a checksum of the current text macro definitions, allowing the host to insure they have not been changed.

CSI   ?     6    3   ; Pid  n
9/11  3/15  3/6  3/3 ; Pid  6/14

Description: This request causes a Checksum Report (DECCKSR) to be issued reporting the checksum of current text macro definitions.

Pid is an optional numeric parameter which provides a label to identify the checksum request. It will be provided in the DECCKSR response from the terminal. This label serves to differentiate between multiple checksum reports if necessary.

Checksum Report — DECCKSR

Level: 4

Purpose: To report a requested checksum.

DCS  Pn  !    ~     D...D  ST
9/0  Pn  3/2  7/14  D...D  9/12

Description: DECCKSR is issued in response to a Request Checksum of Rectangular Area (DECRQCRA) or a Device Status Report (DSR) with a parameter value of ?63 indicating a request for a checksum of the macro definitions.

The numeric parameter of the DECCKSR control string is a numeric label for the checksum report specified in the DECRQCRA or DSR control function. This label serves to differentiate between multiple checksum reports if necessary.

The data of the control string consists of four hexadecimal digits (3/0 through 3/9 and 4/1 through 4/6) indicating the checksum.

Define Macro — DECDMAC

Level: 4

Purpose: To define a string of characters as a text macro, allowing the host to shorten subsequent transmissions.

DCS  Pid ; Pdt ; Pen  !    z     D...D  ST
9/0  Pid ; Pdt ; Pen  2/1  7/10  D...D  9/12

Where

• Pid is the macro ID number: 0-63.
• Pdt is the delete control:
  • 0 delete only a macro with the same ID number (if one exists) before defining this macro.
  • 1 delete all macro definitions before defining this macro.
• Pen is the macro encoding:
  • 0 text (ASCII) encoding.
  • 1 hex pair encoding.

Description: This control string defines a macro consisting of ANSI commands. Once defined, a macro can be invoked using DECINVM to cause the macro's definition to be processed by the terminal as if received from the host.

Omitted parameters are defaulted to zero. Pid must be a number between 0 and 63; Pdt 0 or 1; and Pen 0 or 1; otherwise the control will be ignored.

The data of the control string is the series of text and ANSI commands which are performed when the macro is invoked.

Macros can invoke other macros with up to 16 levels of nesting, but cannot invoke themselves recursively. Macro definitions cannot be nested. That is, a DECDMAC cannot be included as part of a macro definition.

When text encoding is used (Pen = 0), the macro consists of the graphic characters appearing in the control string. Only characters from 2/0 through 7/14 and 10/00 through 15/15 may be included in a macro using this encoding method.

When hex pair encoding is used (Pen = 1), each pair of characters in the definition represents the hex value of a single ASCII character which will be stored in the definition of the macro. If a non-hex pair is encountered that is not a valid repeat sequence, the entire macro definition is ignored.

A Repeat Introducer (!) is defined to allow a string of hex pairs to be repeated in the definition any number of times. Repeat sequences are imbedded within the text of the macro definition. If a non-hex character is encountered in the repeat string, the entire macro definition is ignored.

The format is:

! Pn ; D...D ;

Where

• ! is the repeat introducer
• Pn is a numeric parameter which specifies the number of times to repeat the sequence. If Pn is not specified, the sequence is inserted into the definition once.
• D...D is the sequence to repeat within the definition, Pn times.
• ; A semicolon separates the repeat count from the sequence of hex pairs. Another semicolon terminates the sequence.

If any non parameter characters are encountered before the first semicolon, the entire macro definition is ignored. If a string terminator is encountered before the final semicolon, the repeat string is terminated normally.

6k bytes of RAM is available for storage of macro definitions. Any macro definitions which cannot fit in the remaining macro storage space are ignored.

All macro definitions are cleared on receipt of a Reset to Initial State (RIS) or Secure Reset (DECSR). Soft Terminal Reset (DECSTR) has no effect on stored macro definitions.

Note that characters from 0/8 through 0/13 can be included to format the device control string, but are not part of the macro definition.

Invoke Macro — DECINVM

Level: 4

Purpose: To invoke a previously defined macro definition.

CSI   Pid  *     z
9/11  Pid  2/10  7/10

Description: Causes the specified macro to be invoked. The macro must have been previously defined using DECDMAC. The terminal substitutes the DECINVM sequence with the contents of the macro definition, and executes the substituted text.

Pid is the macro id number. If a macro is not found with the specified id, the command is ignored.

The current state of the machine is not saved or restored when macros are invoked. Any functions executed by a macro invocation are still in effect when the macro invocation finishes.

If the terminal is in Printer Controller mode, the macro is not expanded by the terminal. The command to invoke the macro is passed on to the printer, to be expanded by the printer's text macro facility.

Macro Space Report — DECMSR

Level: 4

Purpose: To report the space remaining for macro definitions in response to DSR request.

CSI   Pn  *     {
9/11  Pn  2/10  7/11

Description: DECMSR is reported in response to a Device Status Report (DSR) with a private selectable parameter ?62, specifying a request to report the available space for macro definitions.

The numeric parameter specifies the number of bytes available for macro definitions divided by 16 (rounded down).

Save Cursor — DECSC

Levels: 1-4

Purpose: Saves the Active Position and other selective state information.

ESC     7
1/11    3/7

Description: In Level 1 operation, the DECSC control provides a means of storing the values of the Active Position, the Current Rendition, Origin Mode, the currently designated G0, G1, G2, and G3 sets, and the currently invoked GL set.

In Level 2 or higher it also stores the currently invoked GR set. The Current Attribute value is also saved if the Level 2 extension for Selectively Erasable Characters is supported. These values can later be restored using the DECRC control.

Notes:

1. Only one level of storage is provided by this control. Each additional execution of this control will cause previously stored values to be lost.

2. The values of the specified state information (see above) are not affected by the execution of this control.

3. On initialization or reset the values of the save buffer are cleared to the following state:

   position.line = 1;
   position.column = 1;
   position.page = 1;
   rendition.bold = FALSE;
   rendition.underscore = FALSE;
   rendition.blink = FALSE;
   rendition.reverse = FALSE;
   attribute.selective_erase = FALSE;
   origin_mode = ABSOLUTE;
   left = in_use_table.gl;
   right = in_use_table.gr
   g0 = designated_graphic_sets[0];
   g1 = designated_graphic_sets[1];
   g2 = designated_graphic_sets[2];
   g3 = designated_graphic_sets[3];

4. Execution of Soft Terminal Reset (DECSTR) also causes the Save Buffer to be set to the default values as given above.

State Affected:

• save_buffer_t cursor_save_buffer;

Algorithm:

void save_cursor()
{
cursor_save_buffer.position.line =
            active_position.line;
cursor_save_buffer.position.column =
            active_position.column;
cursor_save_buffer.position.page =
            active_position.page;
cursor_save_buffer.rendition.bold =
           current_rendition.bold;
cursor_save_buffer.rendition.underscore =
           current_rendition.underscore;
cursor_save_buffer.rendition.blink =
           current_rendition.blink;
cursor_save_buffer.rendition.reverse =
           current_rendition.reverse;
cursor_save_buffer.origin_mode = origin_mode;
cursor_save_buffer.left = in_use_table.gl;
cursor_save_buffer.g0 = designated_graphic_sets[0];
cursor_save_buffer.g1 = designated_graphic_sets[1];
cursor_save_buffer.g2 = designated_graphic_sets[2];
cursor_save_buffer.g3 = designated_graphic_sets[3];
if (conformance_level >= LEVEL_2)
  {
  cursor_save_buffer.right = in_use_table.gr;
  cursor_save_buffer.attribute.selective_erase =
                     current_attribute.selective_erase;
  }
} /* end save_cursor */

Known Deviations: None

Restore Cursor — DECRC

Levels: 1-4

Purpose: Restores the previously saved values of the Active Position and other selective state information.

ESC     8
1/11    3/8

Description: In Level 1 operation, the DECRC control provides a means of restoring the values of the Active Position, the Current Rendition, Origin Mode, the currently designated G0, G1, G2, and G3 sets, and the currently invoked GL set.

In Level 2 or higher it also restores the currently invoked GR set. The Current Attribute value is also saved if the Level 2 extension for Selectively Erasable Characters is supported. These values are the ones which were previously stored using the Save Cursor (DECSC) control function.

Notes:

1. The values of the specified state information (see above) at the time this control is received by the terminal are lost.

2. The values stored in the Cursor Save Buffer are not affected by execution of this control.

3. If the restored cursor position lies outside of the scrolling region, and the restored value of Origin Mode is set, the Active Position will be moved to the closest position within the scrolling region. That is, if the restored cursor position is above the Top Margin, the Active Position will be set to the Top Margin, and if the restored position is below the Bottom Margin, the Active Position will be set to the Bottom Margin. In either case, the Active Column will not change, but will remain as the stored column value. For example: the Active Position is at line 5, column 5 when the cursor is saved, and Origin Mode is set; the scrolling region is subsequently changed to 10,15; when the cursor is restored, the Active Position will be moved to line 10, column 5, to insure that it will lie inside the scrolling region. This reason for this recovery is to guarantee that the Active Position will always be within the bounds of the scrolling region, and will never have a negative value.

State Affected:

• active_position
• current_rendition
• origin_mode
• in_use_table
• designated_graphic_sets[4]
• current_attribute

Algorithm:

void restore_cursor()
{
  short int base;  /* first line(-1) of page */
if (cursor_save_buffer.position.page > number_of_pages)
  active_position.page = number_of_pages;
else active_position.page = cursor_save_buffer.position.page;
base = (active_position.page-1) * lines_per_page;
if (cursor_save_buffer.position.column >
    end_of_line(active_position.line + base))
  active_position.column = end_of_line(active_position.line +
base);
else
  active_position.column = cursor_save_buffer.position.column;
active_position.line = cursor_save_buffer.position.line;

current_rendition.bold =
  cursor_save_buffer.rendition.bold;
current_rendition.underscore =
  cursor_save_buffer.rendition.underscore;
current_rendition.blink =
  cursor_save_buffer.rendition.blink;
current_rendition.reverse =
  cursor_save_buffer.rendition.reverse;

origin_mode = cursor_save_buffer.origin_mode;
if (origin_mode == DISPLACED)
  {
  if (active_position.line < top_margin)
    active_position.line = top_margin;
  if (active_position.line > bottom_margin)
    active_position.line = bottom_margin;
  if (active_position.column < left_margin)
    active_position.column = left_margin;
  if (active_position.column > right_margin)
    active_position.column = right_margin;
  }

in_use_table.gl = cursor_save_buffer.left;
designated_graphic_sets[0] = cursor_save_buffer.g0;
designated_graphic_sets[1] = cursor_save_buffer.g1;
designated_graphic_sets[2] = cursor_save_buffer.g2;
designated_graphic_sets[3] = cursor_save_buffer.g3;

if (conformance_level >= LEVEL_2)
  {
  in_use_table.gr = cursor_save_buffer.right;
  if (level_2_extensions[SELECTIVE_ERASE]==TRUE)
    current_attribute.selective_erase =
      cursor_save_buffer.attribute.selective_erase;
  }
}

Known Deviations:

In the VT100, VT101, VT102, VT125, VT131, and VT132, if the restored cursor position lies outside of the scrolling region, and the restored value of Origin Mode is set, the Active Position will not be moved into the scrolling region, and an illegal (e.g., negative) cursor position value may result.

Request Mode — DECRQM

Levels: 2x (TSI), 3-4

Purpose: To request the state of modes controlled by Set Mode/⁠Reset Mode sequences.

CSI         Ps  $    p      (ANSI modes)
CSI   ?     Ps  $    p      (DEC private modes)
9/11  3/15  Ps  2/4  7/0

Description: This sequence takes one selective parameter specifying a single selectable mode controllable using the Set Mode and Reset Mode sequences. The terminal responds with a Report Mode control sequence (DECRPM) which specifies the state of the mode as follows: (0) Unknown (mode is not recognized by terminal); (1) Set; (2) Reset; (3) Set and cannot be changed; or (4) Reset and cannot be changed.

All ANSI standard modes defined in X3.64-1979 are reported as either Set or Reset. DEC Private modes that cannot be set or reset from the host will report as unknown [Reason: the list is long and changes frequently. Since DEC defines these modes, applications can infer how to handle unknown modes as needed].

Report Mode — DECRPM

Levels: 2x (TSI), 3-4

Purpose: To report the state of modes controlled by Set Mode/⁠Reset Mode sequences (terminal to host).

CSI         Ps1 ; Ps2  $    y      (ANSI modes)
CSI   ?     Ps1 ; Ps2  $    y      (DEC private modes)
9/11  3/15  Ps1 ; Ps2  2/4  7/9

Description: This sequence is returned to the host upon receipt of a valid DECRQM control sequence. This sequence reports the state of a particular selectable mode to the host. The first selective parameter (Ps1) is the selectable mode number (the question mark ("?") must be added for DEC private selectable modes), that was requested from the DECRQM sequence. The second selective parameter (Ps2) indicates the state of that mode:

Request Selection Or Setting — DECRQSS

Levels: 2x (TSI), 3-4

Purpose: To request the state of a selection or setting which is not encoded as a Set Mode/Reset Mode sequence.

DCS  $    q    D...D  ST
9/0  2/4  7/1  D...D  9/12

Description: Request Selection or Setting is sent to the terminal to determine the selection or setting of a single device feature, such as the current Graphic Rendition (SGR). The data of the device control string for DECRQSS contains the identifying intermediate and final characters of the control sequence used to make the selection. For example, if the command is to request the state of SGR, the data would consist of a single character 'm', which is the final character (no intermediates) in the control sequence for SGR. The terminal responds with a Report Selection or Setting (DECRPSS) sequence.

Only one setting or selection may be queried per request.

Report Selection Or Setting — DECRPSS

Levels: 2x (TSI), 3-4

Purpose: To report the state of a selection or setting which is not encoded as a Set Mode/Reset Mode sequence (terminal to host).

DCS  Ps  $    r    D...D  ST
9/0  Ps  2/4  7/2  D...D  9/12

Description: The Report Selection or Setting device control string is issued from the terminal in response to a Request Selection or Setting command. The value of Ps indicates whether the Request was successful:

The data returned by the DECRPSS control string is the entire control function that the host would send to the terminal to select or set the parameter being inquired, based on the current setting or selection of that parameter, with the single exception of the leading Control Sequence Introducer character (9/11, or 1/11 5/11 in 7 bits).

The returned control function will contain no omitted parameters, even if the inquired value is the default value. In the case where there is no default value for the inquired parameter, the returned control function will be constructed so as to overwrite the existing setting or selection, if and when that information is returned to the device.

For example, if the current Graphic Rendition is blinking, and reversed, the data would consist of the characters '0;5;7m', which is the parameter string and final character necessary to change the graphic rendition to that state.

Note that the coding of the DECRPSS control string which indicates UNKNOWN, is always coded as follows:

DCS 0 $ r ST

Request Presentation State Report — DECRQPSR

Levels: 2x (TSI), 3-4

Purpose: To request presentation state (cursor information and tab stops).

CSI  Ps   $    w
9/11  Ps  2/4  7/7

Description: DECRQPSR causes the terminal to respond with a Presentation State Report (DECPSR). The control sequence takes one selective parameter which specifies the type of Presentation State Report to be returned.

Presentation State Report — DECPSR

Levels: 2x (TSI), 3-4

Purpose: To report the presentation state (cursor information and tab stops, terminal to host).

DCS  Ps  $    u    D...D  ST
9/0  Ps  2/4  7/5  D...D  9/12

Description: The Presentation State Report is a device control string containing data which represents the settings of presentation attributes in the terminal. A Presentation State Report is sent in response to a Request Presentation State Report control sequence (DECRQPSR).

The type of Presenation State Report is specified by the value of Ps:

Cursor Information Report — DECCIR

Levels: 2x (TSI), 3-4

Purpose: To report the presentation state cursor information

DCS  1    $    u    D...D  ST
9/0  3/1  2/4  7/5  D...D  9/12

Description: The data of a device control string for a Cursor Information Report consists of a string of parameters containing the information saved through a Save Cursor (DECSC) command, according to the following format:

Pr ; Pc ; Pp ; Srend ; Satt ; Sflag ; Pgl ; Pgr ; Scss ; Sdesig

where:

• Pr, Pc — The cursor position (example: 24;132)

• Pp — The current page (example: 3)
  Note that in a single page configuration, the Pp parameter would be 1.

• Srend — One or more bytes containing the encoded Graphic Renditions that must be saved, according to the following bit-encoded format:

  bit 8:	always reset (0)
  bit 7:	always set (1)
  bit 6:	extension indicator: if this bit is set (1), another byte of rendition information follows (always reset on VT420).
  bit 5:	always reset (0)
  bit 4:	reverse video rendition
  bit 3:	blink rendition
  bit 2:	underline rendition
  bit 1:	bold rendition

  For the actual rendition bits (1 through 5, above) if the bit is set (1), it indicates that the rendition has been selected. Example: if bold and underline are set the terminal would report a single byte, coded in binary as 01000011, or a hex 43, ASCII "C".

• Satt — One or more bytes containing the encoded Character Attributes that must be saved, according to the following bit-encoded format:

  bit 8:	always reset (0)
  bit 7:	always set (1)
  bit 6:	extension indicator: if this bit is set (1), another byte of character attribute information follows (always reset on VT420).
  bit 5:	reserved for future use
  bit 4:	reserved for future use
  bit 3:	reserved for future use
  bit 2:	reserved for future use
  bit 1:	selectively erasable attribute

  For the actual character attribute bits (1 through 5, above) if the bit is set (1), it indicates that the character attribute has been selected. Example: if the selective erase attribute is set, the terminal would report a single byte, coded in binary as 01000001, or a hex 41, ASCII "A".

• Sflag — One or more bytes containing several flags and modes that must be saved, according to the following bit-encoded format:

  bit 8:	always reset (0)
  bit 7:	always set (1)
  bit 6:	extension indicator: if this bit is set (1), another byte of flags follows (always reset on VT420).
  bit 5:	reserved for future use
  bit 4:	auto-wrap pending (1 if pending)
  bit 3:	SS3 pending (1 if SS3 received)
  bit 2:	SS2 pending (1 if SS2 received)
  bit 1:	origin mode (1 = set 0 = reset)

  For the flags above, if the bit is set (1) it indicates that the mode or state is set (as indicated). Example: if origin mode DECOM is set, auto-wrap is pending, and an SS3 has been received, the terminal would report a single byte, coded in binary as 01001101, or a hex 4D, ASCII "M".

• Pgl, Pgr — Character G-sets which are currently invoked into GL and GR. These parameters are characters from 0 through 3, depending on which of G0, G1, G2, or G3 are invoked into GL and GR, respectively.

• Scss — One byte containing the encoded information regarding the size of the character sets designated into G0 through G3 according to the following bit-encoded format:

  bit 8:	always reset (0)
  bit 7:	always set (1)
  bit 6:	extension indicator: if this bit is set (1), another byte of character size information follows (always reset on VT420).
  bit 5:	reserved for future use
  bit 4:	size of G3 set
  bit 3:	size of G2 set
  bit 2:	size of G1 set
  bit 1:	size of G0 set

  For the character set size bits (1 through 4, above) if the bit is set (1), it indicates that the graphic set contains a 96-character character set. If the bit is reset, the graphic set contains a 94-character character set. Example: if ISO Latin Alphabet Nr 1 Supplemental, a 96-character character set is designated into G2 and G3, and ASCII, a 94-⁠character character set is designated into G0 and G1, the terminal would report a single byte, coded in binary as 01001100 = hex 4C = ASCII "L".

• Sdesig — A string of bytes which consist of the strings of designating tails of the character sets designated into G0, G1, G2, and G3, in that order. The designating tail consists of the intermediate and final characters of the Select Character Set (SCS) designating escape sequence for the character set.

  (Example: If ASCII were designated into G0, the Line Drawing (DEC Special Graphics) set into G1, and the DEC Supplemental Set into G2 and G3, the value of Sdesig would be: 'B0%5%5')

  Note: this string is deliberately placed at the end of the data of the DECCIR control string, because the semicolon (;) separator character used between the previous parameters is a valid character in a SCS escape sequence.

  Note: This string will report the User Preference Supplemental Set (UPSS) designator if that is how a character set was designated. DECRQUPSS can be used to determine the actual UPSS if needed.

Tabulation Stop Report — DECTABSR

Levels: 2x (TSI), 3-4

Purpose: To report the presentation state tab stops

DCS  2    $    u    D...D  ST
9/0  3/2  2/4  7/5  D...D  9/12

Description: The data of a device control string for a Tabulation Stop Report consists of a string of numeric parameters specifying where tabulation stops are currently set in the terminal, separated by slash ("/") characters. An example of a DECTABSR when the terminal has 8 column tabs set would be as follows:

DCS 2 $ u 9 / 17 / 25 / 33 / 41 / 49 / 57 / 65 / 73 ST

Restore Presentation State — DECRSPS

Levels: 2x (TSI), 3-4

Purpose: To report previously reported presentation state (cursor information or tab stops).

DCS  Ps   $    t    D...D  ST
9/0  Ps   2/4  7/4  D...D  9/12

Description: This device control string is sent to reset the terminal to the presentation state described in the data of the control string. This DCS takes one selective parameter, which indicates the format of the data of the DCS. The data of the DCS must be in the format of one of the Presentation State Reports (DECPSR). The type of DECPSR format that the data consists of is specified by the selective parameter:

When this sequence is received by the terminal, the terminal will begin to change the terminal state according to the state encoded in the data of the control string.

If an invalid value is detected, the terminal will ignore the error, if possible, and if not will ignore the remainder of the data, parsing until a ST control is encountered. This may leave the terminal state partially unrestored. No error indication is returned to the host.

Request Terminal State Report — DECRQTSR

Levels: 2x (TSI), 3-4

Purpose: To request a compact report of most settable state.

CSI   Ps  $    u
9/11  Ps  2/4  7/5

Description: DECRQTSR causes the terminal to issue a Terminal State Report (DECTSR). Terminal State Reports transmit information on global state within the terminal. The type of DECTSR returned depends on the value of the selective parameter.

If the terminal does not recognize the type of DECTSR requested, the entire command is ignored.

Terminal State Report (1) — DECTSR

Levels: 2x (TSI), 3-4

Purpose: To report most settable terminal state in one compact sequence.

DCS  1    $    s    D...D  ST
9/11 3/1  2/4  7/3  D...D  9/12

Description: The Terminal State Report is a device control string containing a collection of terminal device attributes. A Terminal State Report is sent in response to a Request Terminal State Report control sequence (DECRQTSR) with Selective Parameter "1".

The data of the device control string for a Terminal State Report consists of a Sixel encoded, string of 8-bit bytes which contains the the state information for the device. This string is guaranteed not to be longer than 256 characters, including the DCS control character, introducer sequence, and ST control character.

The state information reported is the same as the state information available through the other discrete TSI controls. This generally represents all settable state in the terminal with the exception of large data items that are not practical to report (the contents of the logical display, DRCS, UDK definitions, and Macros).

The format of the data is firmware revision dependent. Software should not expect the format to remain the same across firmware revisions or different members of a terminal family.

The format of DECTSR is: DCS 1 $ s D1...Dn <checksum1> <checksum2> ST

Where

• D1...Dn are data reported
• <checksum1> <checksum2> is a two bytes check sum of D1...Dn

(checksum = 2's complement of D1 + D2 + ... + Dn; 8-bit addition with no Carry)

Restore Terminal State — DECRSTS

Levels: 2x (TSI), 3-4

Purpose: To restore previously reported terminal state (DECTSR).

DCS  Ps  $    p    D...D  ST
9/0  Ps  2/4  7/0  D...D  9/12

Description: This device control string is sent to reset the terminal to the state described in the data of the control string. This DCS takes one selective parameter, which indicates the format of the data of the DCS. The data of the DCS must be in the format of one of the Terminal State Reports (DECTSR). The type of DECTSR format that the data consists of is specified by the selective parameter:

When this sequence is received, buffered, and checksummed by the terminal, the terminal will begin to change the terminal state according to the state encoded in the data of the control string. If the checksum fails, the entire sequence is ignored. If an invalid value is detected, the terminal will ignore the error if possible, and if not, ignore the remainder of the data, parsing until a ST control is encountered. This may leave the terminal in a partially unrestored state. No error indication is returned to the host.