VT100 (enhanced) Programmer Information (Draft)

Background

The VT132 faithfully implements almost all of the features of the original Digital Equipment Corporation (DEC) VT100, with the Advanced Video Option installed.

To this a range of enhancements have been added

  • many are features of later DEC VT family terminals that have been implemented for convenience
  • some are features of "standard" ANSI terminals (mainly IBM PC/MS DOS based terminal emulators)
  • enhancements are highlighted by the addition of (enhancement) to the heading or description

A good reference for an owner of a VT100 (especially getting started with the Setup screens) is the original VT100 Users Guide over at VT100.net. Details of what the Advanced Video Option adds can be found here also.

The remainder of this section will largely focus on where the VT132 implementation of the VT100 differs to an original VT100.

TIP

Each heading is a link to the corresponding section of Chapter 3 of the original VT100 Users Guide

The Keyboard

LED Indicators

The original VT100 keyboard had 7 LED indicators, the VT132 does not.

On the VT132:

  • The ON-LINE/LOCAL status is indicated on each Setup screen in the top right-hand corner as either ONLINE or LOCAL and also in the Quick Menu, on the root menu, by the checkbox item [X]On-line for ON-LINE and [ ]On-line for LOCAL.
  • There is no support for the "keyboard locked" condition.
  • The four remaining, programmable LEDs are represented as follows:
    • L1, L2 and L3 are mapped to the 3 PC keyboard LEDs for <Num Lock>, <Caps Lock> and <Scroll Lock> (if present)
      • Sending an escape sequence to turn on/off any of L1, L2 or L3 will change the corresponding LED on the keyboard
      • Pressing one of the 3 key-lock keys <Num Lock>, <Caps Lock> and <Scroll Lock> will override the value displayed for L1, L2 or L3
    • L4 is not mapped to anything is so is not visible

SET-UP

The SET-UP key is mapped to <Alt><SysReq> or <Alt><PrintScreen>

NO SCROLL

The NO SCROLL key is mapped to the <Scroll Lock> key on a PC keyboard and is equivalent to pressing <Ctrl><S> and <Ctrl><Q> alternatively.

BREAK

The BREAK key function is not implemented by the VT132.

Communications Protocols

Full Duplex

The VT132 supports baud rates from 300 to 115200 and the Transmit and Receive speed must be the same. The available speeds are 300, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200 corresponding to the speeds supported by most serial interface cards based on the available clock settings.

Terminal Control Commands

Control Characters

The following table details the control characters the VT132 responds to.

There are two columns indicating whether the control character action is implemented, one for VT100 mode and one for ANSI.SYS compliance mode as the set of control characters differs depending on the current mode.

Control Character Octal Code Hex Code Action Taken VT100 ANSI.SYS
NUL 000 0x00 Ignored on input No No
ENQ 005 0x05 Transmit answer-back message Yes No
BEL 007 0x07 Sound bell tone from buzzer Yes Yes
BS 010 0x08 Move the cursor to the left one character position, unless it is at the left margin, in which case no action occurs Yes Yes
HT 011 0x09 Move the cursor to the next tab stop, or to the right margin if no further tab stops are present on the line Yes Yes
LF 012 0x0A This code causes a line feed or a new line operation. (See new line mode). Yes Yes
VT 013 0x0B Interpreted as LF - TBA Yes Yes
FF 014 0x0C Interpreted same as VT Yes Yes
CR 015 0x0D Move cursor to the left margin on the current line Yes Yes
SO 016 0x0E Invoke G1 character set, as designated by SCS control sequence. Yes No
SI 017 0x0F Select G0 character set, as selected by ESC ( sequence Yes No
XON 021 0x11 Causes terminal to resume transmission Yes Yes
XOFF 023 0x13 Causes terminal to stop transmitted all codes except XOFF and XON Yes Yes
SUB 030 0x18 Not implemented No No
CAN 032 0x1A Not implemented No No
ESC 033 0x1B Invokes a control sequence Yes Yes
DEL 177 0x7F Ignored on input Yes Yes

TIP

Control Characters in the ranges named C0 (0x00-0x1F) and C1 (0x80-0x9F) are normally considered non-printable characters. This is true for the VT100 (and all terminal personalities included in the VT132).

The exception is when ANSI.SYS compliance is enabled.

In this mode only the Control Characters listed above with Yes in the ANSI.SYS column are considered non-printable. All other Control Characters will be output to the terminal, showing the corresponding glyph from the currently selected font. This is designed to allow a greater range of the CP437 character set to be output to the terminal and many of these glyphs are used in BBSs to display extra symbols and also in ANSI art.

Control Sequences

The following tables of Control Sequences are grouped into 4 categories:

Original VT100 Control Sequences

Control Sequence Name Action Taken Default Value
ESC [ Pn ; Pn R CPR Cursor Position Report
Response to DSR
ESC [ Pn D CUB Cursor Backward 1
ESC [ Pn B CUD Cursor Down 1
ESC [ Pn C CUF Cursor Forward 1
ESC [ Pn ; Pn H CUP Cursor Position 1
ESC [ Pn A CUU Cursor Up 1
ESC [ Pn c DA Device Attributes 0
ESC [ ? 1 ; Pn c DA Device Attributes response
Hardcoded to:
Esc [ ? 64 ; 1 ; 6 ; 22 c
ESC # 8 DECALN Screen Alignment Display
ESC [ ? 2 l DECANM ANSI/VT52 Mode
ESC [ ? 8 h/l DECARM Auto Repeat Mode
ESC [ ? 7 h/l DECAWM Auto-wrap Mode
ESC [ ? 1 h/l DECCKM Cursor Keys Mode
ESC [ ? 3 h/l DECCOLM 132/80 Column Mode
ESC # 3 DECDHL Double Height Line -Top Half
ESC # 4 DECDHL Double Height Line - Bottom Half
ESC # 6 DECDWL Double Width Line
ESC Z DECID Identify Terminal
ESC [ ? 9 h/l DECINLM Interlace Mode
480/240 scan lines
ESC = DECKPAM Keypad Application Mode
ESC > DECKPNM Keypad Numeric Mode
ESC [ Ps q DECLL Load LEDS 0
ESC [ ? 6 h/l DECOM Origin Mode
ESC 8 DECRC Restore Cursor
Paired with DECSC
ESC [ <sol>; ... x DECREPTPARM Report Terminal Parameters
NOT IMPLEMENTED
ESC [ <sol> x DECREQTPARM Request Terminal Parameters
NOT IMPLEMENTED
ESC 7 DECSC Save Cursor
Paired with DECRC
ESC [ ? 4 h/l DECSCLM Scrolling Mode
Smooth/Jump scrolling
ESC [ ? 5 h/l DECSCNM Screen Mode
Reverse/Normal
ESC [ Pn; Pn r DECSTBM Set Top and Bottom Margins
Minimum 2 lines
whole screen
ESC # 5 DECSWL Single-width Line
ESC [ 2 ; Ps y DECTST Invoke Confidence Test
NOT IMPLEMENTED
ESC [ Ps n DSR Device Status Report 0
ESC [ Ps J ED Erase In Display 0
ESC [ Ps K EL Erase In Line 0
ESC H HTS Horizontal Tabulation Set
ESC [ Pn ; Pn f HVP Horizontal and Vertical Position 1
ESC D IND Index
ESC [ 20 h/l LNM Line Feed/New Line Mode
ESC E NEL Next Line
ESC M RI Reverse Index
ESC c RIS Reset To Initial State
ESC [ Ps ; ... l RM Reset Mode none
SCS Select Character Set
ESC ( A SCS - G0 G0 - United Kingdom Set
ESC ( B SCS - G0 G0 - ASCII Set
ESC ( 0 SCS - G0 G0 - Special Graphics
ESC ( 1 SCS - G0 G0 - Alt Standard Character Set
ESC ( 2 SCS - G0 G0 - Alt Special Graphics
ESC ) A SCS - G1 G1 - United Kingdom Set
ESC ) B SCS - G1 G1 - ASCII Set
ESC ) 0 SCS - G1 G1 - Special Graphics
ESC ) 1 SCS - G1 G1 - Alt Standard Character Set
ESC ) 2 SCS - G1 G1 - Alt Special Graphics
ESC [ Ps ; ... m SGR Select Graphics Rendition
ESC [ 0 m SGR Attributes Off
ESC [ 1 m SGR Bold or Increased Intensity
ESC [ 4 m SGR Underscore
ESC [ 5 m SGR Blink
ESC [ 7 m SGR Negative (reverse/inverse) image
ESC [ Ps ; ... h SM Set Mode
ESC [ Ps g TBC Tabulation Clear 0

Additional Control Sequences

Control Sequence Mnemonic Action Taken Notes

TBA

ANSI.SYS Control Sequences

Control Sequence Mnemonic Action Taken Notes
ESC [ s SCOSC Save current cursor state (position and attributes) Does the same as ESC 7
ESC [ u SCORC Restore current cursor state (position and attributes) Does the same as ESC 8

Original VT52 Control Sequences

Control Sequence Action Taken
ESC A Cursor Up
ESC B Cursor Down
ESC C Cursor Right
ESC D Cursor Left
ESC F Enter Graphics Mode
ESC G Exit Graphics Mode
ESC H Cursor to Home
ESC I Reverse Line Feed
ESC J Erase to End of Screen
ESC K Erase to End of Line
ESC Y line column Direct Cursor Address
ESC Z Identify
ESC / Z Identify response
ESC = Enter Alternate Keypad Mode
ESC > Exit Alternate Keypad Mode
ESC < Enter ANSI Mode
Last Updated: 10/16/2020, 11:34:17 AM