Editing VT52 (section)

=== Standard commands ===

VT52 commands normally consisted of the escape character and a single character following it. The exception to this rule was the Y command, which also required two numbers to be sent.

{| class="wikitable"
! Code
! Name
! Meaning
! Available on
|-
| {{keypress|ESC|A|chain=}}
| Cursor up
| Move cursor one line upwards.<br>Does not cause scrolling when it reaches the top.
| All
|-
| {{keypress|ESC|B|chain=}}
| Cursor down
| Move cursor one line downwards.
| VT50H and VT52
|-
| {{keypress|ESC|C|chain=}}
| Cursor right
| Move cursor one column to the right.
| All
|-
| {{keypress|ESC|D|chain=}}
| Cursor left
| Move cursor one column to the left. Same action as the {{key|BS}}.
| VT50H and VT52
|-
| {{keypress|ESC|F|chain=}}
| Enter graphics mode
| Use special graphics character set.
| VT52
|-
| {{keypress|ESC|G|chain=}}
| Exit graphics mode
| Use normal US/UK character set.
| VT52
|-
| {{keypress|ESC|H|chain=}}
| Cursor home
| Move cursor to the upper left corner.
| All
|-
| {{keypress|ESC|I|chain=}}
| Reverse line feed
| Move cursor one line upwards.<br>If it is already in the top line, instead scroll all content down one line.
| VT52
|-
| {{keypress|ESC|J|chain=}}
| Clear to end of screen
| Clear screen from cursor onwards.
| All
|-
| {{keypress|ESC|K|chain=}}
| Clear to end of line
| Clear line from cursor onwards.
| All
|-
| {{keypress|ESC|Y|r|c|chain=}}
| Set cursor position
| Move cursor to position c,r, encoded as single characters.<br>The VT50H also added the "SO" command that worked identically,<br>providing backward compatibility with the VT05. The VT52 did not support this alternate command.
| VT50H and VT52
|-
| {{keypress|ESC|Z|chain=}}
| ident
| Identify what the terminal is, see notes below.
| All
|-
| {{keypress|ESC|[|chain=}}
| Enter hold-screen mode
| Stops display scrolling of the screen.<br>Characters continue to be displayed until they reach the point where a scroll would occur,<br>at which point the terminal sends an {{code|XOFF}} to the host to stop further data being sent.<br>If the user presses the {{key|SCROLL}} key, an {{code|XON}} is sent and data is displayed until the next<br>point where a scroll would be needed, when another {{code|XOFF}} will be sent.
| All
|-
| {{keypress|ESC|\|chain=}}
| Exit hold-screen mode
| Turns off hold-screen mode sends an {{code|XON}} if needed.
| All
|-
| {{keypress|ESC|{{=}}|chain=}}
| Enter alternate-keypad mode
| Changes the character codes returned by the keypad.
| VT52
|-
| {{keypress|ESC|>|chain=}}
| Exit alternate-keypad mode
| Changes the character codes returned by the keypad.
| VT52
|}

====Cursor positioning====
The {{keypress|ESC|Y|chain=}} code was used to position the cursor anywhere on the screen, using two parameters representing the X and Y coordinates of the cursor position, with the upper left corner of the screen being position 1,1. These numbers were sent as ASCII characters of that value, adding 31. For instance, to position the cursor at column 30 and line 20, you would add 31 to each value to get 61 and 51, then look up those ASCII characters, {{keypress|{{=}}}} and {{keypress|3}}. The complete command would then be {{keypress|ESC|Y|3|{{=}}|chain=}} (note the row, column ordering, not X, Y).{{sfn|DECscope|1975|pp=20, 21}} Adding 31 ensures that the characters are shifted out of the control range into the printable character range, so they will transmit properly.

====Terminal identifier codes====
The {{keypress|ESC|Z|chain=}} command allowed the host computer to identify the capabilities of the terminal. There were eight possible responses.

{| class="wikitable"
! Model
! Without printer
! With printer
|-
| VT50
| {{keypress|ESC|/|A|chain=}}
| (not available)
|-
| VT50H
| {{keypress|ESC|/|H|chain=}}
| {{keypress|ESC|/|J|chain=}}
|-
| VT52
| {{keypress|ESC|/|K|chain=}}
| {{keypress|ESC|/|L|chain=}}
|-
| VT55
| {{keypress|ESC|/|E|chain=}}
| {{keypress|ESC|/|E|chain=}}
|}

====Copier codes====
Several additional codes were used with the optional copier:{{sfn|Copier|1975|p=3}}

{| class="wikitable"
! Code
! Name
! Meaning
! Available on
|-
| {{keypress|ESC|]|chain=}}
| Copy screen
| Prints the current screen.
| All
|-
| {{keypress|ESC|^|chain=}}
| Enter auto-copy mode
| Prints all subsequent lines.
| All
|-
| {{keypress|ESC|_|chain=}}
| Exit auto-copy mode
| Stops printing.
| All
|}

====Graphics mode====
The VT52 and VT55 included two characters sets, ASCII and "graphics mode" which switched out the lower case characters and some punctuation with new characters useful for the display of math. Unusual were glyphs for ¹⁄, ³⁄, ⁵⁄, ⁷⁄, which could be combined with subscript numbers to produce things like ⅗, and scan lines allowing a function to be plotted with 8 times higher vertical resolution than text.{{sfn|DECscope|1975|pp=24, 25, Appendix B}}

{|{{chset-table-header1|VT52 Graphics Mode (gray cells are the same as ASCII)}}
|-
|{{chset-left1|5x}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-cell1|||style=background:#DDD}}
|{{chset-ctrl1|94&#10;U+00A0 NO-BREAK SPACE|[[NBSP]]}}
|{{chset-ctrl1|95&#10;U+00A0 NO-BREAK SPACE|[[NBSP]]}}
|-
|{{chset-left1|6x}}
|{{chset-cell1|||fn={{efn|Reserved for future use}}}}
|{{chset-cell1|97&#10;U+2588 FULL BLOCK|█|}}
|{{chset-cell1|98&#10;U+215F FRACTION NUMERATOR ONE|¹⁄}}
|{{chset-cell1|99&#10;U+00B3 SUPERSCRIPT THREE, U+2044 FRACTION SLASH|³⁄}}
|{{chset-cell1|100&#10;U+2075 SUPERSCRIPT FIVE, U+2044 FRACTION SLASH|⁵⁄}}
|{{chset-cell1|101&#10;U+2077 SUPERSCRIPT SEVEN, U+2044 FRACTION SLASH|⁷⁄}}
|{{chset-cell1|102&#10;U+00B0 DEGREE SIGN|[[°]]|102}}
|{{chset-cell1|103&#10;U+00B1 PLUS-MINUS SIGN|[[±]]|103}}
|{{chset-cell1|104&#10;U+2192 RIGHTWARDS ARROW|→}}
|{{chset-cell1|105&#10;U+2026 HORIZONTAL ELLIPSIS|[[…]]}}
|{{chset-cell1|106&#10;U+00F7 DIVISION SIGN|[[÷]]}}
|{{chset-cell1|107&#10;U+2193 DOWNWARDS ARROW|↓}}
|{{chset-cell1|108&#10;U+2594 UPPER ONE EIGHTH BLOCK|▔}}
|{{chset-cell1|109&#10;U+1FB76 HORIZONTAL ONE EIGHTH BLOCK-2|🭶}}
|{{chset-cell1|110&#10;U+1FB77 HORIZONTAL ONE EIGHTH BLOCK-3|🭷}}
|{{chset-cell1|111&#10;U+1FB78 HORIZONTAL ONE EIGHTH BLOCK-4|🭸}}
|-
|{{chset-left1|7x}}
|{{chset-cell1|112&#10;U+1FB79 HORIZONTAL ONE EIGHTH BLOCK-5|🭹}}
|{{chset-cell1|113&#10;U+1FB7A HORIZONTAL ONE EIGHTH BLOCK-6|🭺}}
|{{chset-cell1|114&#10;U+1FB7B HORIZONTAL ONE EIGHTH BLOCK-7|🭻}}
|{{chset-cell1|115&#10;U+2581 LOWER ONE EIGHTH BLOCK|▁}}
|{{chset-cell1|116&#10;U+2080 SUBSCRIPT ZERO|&#x2080;}}
|{{chset-cell1|117&#10;U+2081 SUBSCRIPT ONE|&#x2081;}}
|{{chset-cell1|118&#10;U+2082 SUBSCRIPT TWO|&#x2082;}}
|{{chset-cell1|119&#10;U+2083 SUBSCRIPT THREE|&#x2083;}}
|{{chset-cell1|120&#10;U+2084 SUBSCRIPT FOUR|&#x2084;}}
|{{chset-cell1|121&#10;U+2085 SUBSCRIPT FIVE|&#x2085;}}
|{{chset-cell1|122&#10;U+2086 SUBSCRIPT SIX|&#x2086;}}
|{{chset-cell1|123&#10;U+2087 SUBSCRIPT SEVEN|&#x2087;}}
|{{chset-cell1|124&#10;U+2088 SUBSCRIPT EIGHT|&#x2088;}}
|{{chset-cell1|125&#10;U+2089 SUBSCRIPT NINE|&#x2089;}}
|{{chset-cell1|126&#10;U+00B6 PILCROW SIGN|[[¶]]}}
|{{chset-cell1|||style=background:#DDD}}
|}