RES=techref.html
function header
{
cat << etx >> $RES
etx
}
cat > $RES /dev/null
# -- HTML Header --------------------------------------------------------------------
cat >> $RES << etx
VT100
etx
# -- Editors Notes ------------------------------------------------------------------
cat >> $RES << etx
VT100
Please note that this text is under construction
Preface
This document accompanies the Konsole program, which is a terminal emulation
for the X Windows System. Since material about the extend and precise semantics
of the emulatation intended to be handled by this programs is hard to find on the
internet today, it came out nessesary to include a more precise specification within
their release.
Hopefully, this helps to clearify the relation to the VT100, VT102, Linux, XTerm
and ansi.sys (ANSI-BBS) terminals, which are the target of these programs. Further,
it specifies which codes are interpreted by them, and what has been omitted.
To begin with, all of the above call themselfes "ANSI" emulations, which makes this
notion pretty vage. "ANSI" referes here to the American National Standards
Institute's documents X3.41-1974 and X3.64-1977. DEC partially implemented this
standart in their VT100 terminal, with some additions. The VT102 is a later extention
of that. Both the Linux console and the XTerm emulation implement most of VT102,
with some additions. MS stepped in later and produced another ANSI emulation,
ansi.sys, for their OS, which became of some relevance in BBS style
telecommunication programs. One can view this as a small subset of the VT100
emulation, with some additions, of cause.
This situation is further confused by the fact, that often many versions of the
above terminals and emulations are out, one able to do a little more or less then
the other.
Currently, the body of this document is mainly a concept data base, that
referes to the VT100 component of the emulation. Though the codes accepted by
konsole are now clearly indicated, a comparison to the xterm and Linux console
emulation is missing.
The konsole emulation sources is not linked closely with it's documentation,
and, also accurate at the time of writing, it can still fall slightly appart.
Work is currently in progress to fix this issue. A decent indexing is on the
way also.
Notes & todos
- Include complete reference on keyboard material.
- Check for explaination of out-of-bound values.
- Include VT52, VT102, XTERM, LINUX-console codes
- Make the whole document more concept oriented
- See the section Method of description, below
- Derive some summarizing lists.
etx
# -- Codes --------------------------------------------------------------------------
header "Terminal Control Commands"
cat >> $RES << etx
The VT100 is an upward and downward software-compatible terminal;
that is, previous Digital video terminals have Digital's private standards
for control sequences. The American National Standards Institute has since
standardized escape and control sequences in terminals in documents X3.41-1974
and X3.64-1977.
The VT100 is compatible with both the previous Digital standard and
ANSI standards. Customers may use existing Digital software designed around
the VT52 or new VT100 software. The VT100 has a "VT52 compatible" mode in
which the VT100 responds to control sequences like a VT52. In this mode, most
of the new VT100 features cannot be used.
Throughout this document references will be made to "VT52 mode" or
"ANSI mode". These two terms are used to indicate the VT100's software
compatibility.
NOTE: The ANSI standards allow the manufacturer flexibility in implementing
each function. This document describes how the VT100 will respond to the
implemented ANSI central function.
Method of description
All the following in this section is an outline.
Parts of the terminal description
- State
This is mainly the screen, the cursor (including it's graphical state)
and some hidden mode variables. Note that the state cannot be investigated
by the attached host.
- Interface
That's what goes over the wire. Beside being related to objects, this
appears so closely related to contemporal process communication, that
it might be discussed in likely terms.
We have information flowing in both directions. On could destinguist
between:
- Commands
These are "calls" of the terminals interface by the host which cause
some change of the terminals state, but do not end in a response.
- Requests
These are "calls" of the terminals interface by the host which do not cause
any change of the terminals state, but end in a response of the terminal.
Clearly, requests are somehow used to investigate the state of the terminal.
- Events
These are signals from the terminal caused by the user affecting the
mouse or keyboard to the host.
- Replys
These are send by the terminal as a result of a Request from the hosts.
- Encoding/Decoding
etx
header "Control Sequences"
cat >> $RES << etx
Conceptually, the commands to the terminal emulation are encoded if form
of byte sequences to meet the restrictions of the transport media. These
sequences have pretty different originations and therefore the format of
the sequences are inhomogenous.
Refering both to their origin and form, one can group the overall encoding
schemes as follows:
| Name | Pattern | Scope | Comment |
| Printable Ascii Characters | 32..126 | ASCII ECMA |
This is the most original pattern of all. The characters to be
displayed are passed over the chanel and are interpreted by the
terminal (emulation) as instructions to display the corresponding
glyph of the ascii character set. Contempory emulations include the
upper half (128..255) of the extentions to the national ascii character
sets, also. |
| Ascii Control Characters | 0..26,28..31,127 | ASCII ECMA |
Ascii defines some non-printable, but format effecting characters, too.
Depending on the emulation, at least some of them are given a meaning.
The typically implemented ones are those that are handled by a teletype
like device. |
| Simple Escape Sequence | ESC C | ECMA |
These sequences are made up from an ESC character followed by
exactly one other character in the range ???..???. |
| CSI Sequence |
ESC [ Parameters {I} C |
ECMA |
|
|
The remaining codes are nonstandard but traditionalized hacks.
|
| DEC hacks |
ESC C D |
VT100 |
|
| XTERM hacks |
ESC ] Pn ; text BEL |
XTERM |
|
|
VT52 uses a different (incompatible) set of escape codes. VT100 includes
the VT52 emulation as a mode.
|
| Simple Escape Sequence | ESC C | VT52 |
|
| Complex Escape Sequence | ESC Y X Y | VT52 |
|
More on Control Sequences
Control Characters
Control characters (codes 0x00 - 0x1f inclusive) are specifically excluded
from the control sequence syntax, but may be embedded within a control
sequence. Embedded control characters are executed as soon as they are
encountered by the VT100. The processing of the control sequence then
continues with the next character recieved. The exceptions are:
if the ESC character occurs, the current control sequence
is aborted, and a new one commences beginning with the ESC
just recieved. If the character CAN (0x0c) or the
character SUB (0x0e) occurs,
the current control sequence is aborted. The ability to embed control
characters allows the synchronization characters XON and XOFF to be
interpreted properly without affecting the control sequence.
FIXME: I've to check this w.r.t. the "I" component in modern
(EMCA) CSI sequences. Evtl. this is not compatible anymore.
CSI Sequences
- Control Sequence Introducer (CSI):
- An escape sequence that provides
supplementary controls and is itself a prefix affecting the
interpretation of a limited number of contiguous characters.
In the VT100, the CSI is: <ESC>[
- Parameter:
- 1. A string of zero or more decimal characters which
represent a single value. Leading zeros are ignored. The
decimal characters have a range of 0 (060) to 9 (071).
2. The value so represented.
- Numeric Parameter:
- A parameter that represents a number, designated by Pn.
- Selective Parameter:
- A parameter that selects a subfunction from a
specified set of subfunctions, designated by Ps. In general, a
control sequence with more than one selective parameter causes
the same effect as several control sequences, each with one
selective parameter, e.g., CSI Psa; Psb; Psc F is identical to
CSI Psa F CSI Psb F CSI Psc F.
- Parameter String:
- A string of parameters separated by a semicolon.
- Default:
- A function-dependent value that is assumed when no explicit
value, or a value of 0, is specified.
- Final character:
- A character whose bit combination terminates an escape or control sequence.
EXAMPLE: Control sequence to turn off all character attributes, then
turn on underscore and blink attributes (SGR).
Delimiters
/ \
/ \
| |
\ / \ /
Sequence: <ESC>[ 0 ; 4 ; 5 m
^^^^^^ ^ ^ ^ ^
|||||| | | | |
\||||/ \ | / +------Final character
\||/ \ | /
CSI Selective
Parameters
The octal representation of this string is:
033 0133 060 073 064 073 065 0155
<ESC> [ 0 ; 4 ; 5 m
Alternate sequences which will accomplish the same thing:
<ESC>[;4;m
<ESC>[m
<ESC>[4m
<ESC>[5m
<ESC>[0;04;005m
DEC hacks
These form two groups of commands.
In one first the first character is a hash (#) and the following a digit.
This command group is used to denote VT100 specific instructions and can
safely be sonsidered to be obsolete. See
DECALN,
DECDHLB,
DECDHLT,
DECDWL and
DECSWL.
The second one is used to specify character set mappings (see SCS). A CSI instruction to do this is specified in ECMA,
and this should be used as a replacement.
XTERM hacks
etx
header "The Concept Data Base"
cat >> $RES << etx
The following text is a collection of several sorts of definitions and
explainations. It is incomplete in many respects and a working draft.
The author is well aware of the fact that this part of the document
is of few use without having proper indexes.
All of the following control sequences are transmitted from the Host to
VT100 unless otherwise noted. All of the control sequences are a subset of
those defined in ANSI X 3.64 1977 and ANSI X 3.41 1974.
The following text conforms to these formatting conventions:
- Individual character literals are set in bold face. Ascii representation
is used throughout, so ESC means the binary value of 27 and
[ a value of 91.
- Parameters are indicated by italic type faces.
- Parameter types usually are indicated as one of:
| Pn | A string of digits representing a numerical value. |
| Ps | A character that selects an item from a list. |
| a-z | Any lowercase sequence of one or more
characters represent a value to be
entered (as in Pn), and the name in the
will be referred to in explanatory text. |
- Spaces are used only to improve readability, they do not occure in the
control sequences unless otherwise indicated.
The following attributes below have the following meaning:
- VT100 - This code is known to VT100.
- ANSI - This code is defined by ANSI.
- DEC - This code is DEC private.
- Command - Sent from host to the terminal. FIXME:add Inquiery.
- Reply - Sent from terminal to the host (as response to an Inquiery).
- Event - Sent from terminal to the host (caused by a user activity).
- Mode - The entry is a mode.
- Host to Terminal (Commands,Requests)
- Commands
- Character Display Operation
- Rendition related status
- Cursor
- Cursor related status
- Edit
- Miscellaneous
- General mode setting
- Miscellaneous status
- VT52
- Not implemented
- Ignored
- Requests
- Terminal to Host (Replies, Events)
- Modes
etx
./genTC.pl >> $RES
header "Modes"
cat >> $RES << etx
The Following is a list of VT100 modes which may be changed with Set
Mode (SM) and Reset Mode (RM) controls.
ANSI Specified Modes
| Parameter | Mnemonic | Function |
|
|
|
| 0 | | Error (Ignored) |
| 20 | LNM | Line Feed/New Line Mode |
DEC Private Modes
If the first character in the parameter string is ? (077), the
parameters are interpreted as DEC private parameters according to the
following:
Any other parameter values are ignored.
The following modes, which are specified in the ANSI standard, may be
considered to be permanently set, permanently reset, or not applicable,
as noted.
| Mnemonic | Function | State |
| CRM | Control Representation | Reset |
| EBM | Editing Boundary | Reset |
| ERM | Erasure | Set |
| FEAM | Format Effector Action | Reset |
| FETM | Format Effector Transfer | Reset |
| GATM | Guarded Area Transfer | NA |
| HEM | Horizontal Editing | NA |
| IRM | Insertion-replacement | Reset |
| KAM | Keyboard Action | Reset |
| MATM | Multiple area transfer | NA |
| PUM | Positioning Unit | Reset |
| SATM | Selected Area Transfer | NA |
| SRTM | Status Reporting Transfer | Reset |
| TSM | Tabulation Stop | Reset |
| TTM | Transfer Termination | NA |
| VEM | Vertical Editing | NA |
etx
# -- Keyboard Codes -----------------------------------------------------------------
cat >> $RES << etx
Keyboard Codes
The notation <ESC> denotes a single ASCII Escape character, 1Bx.
| Cursor Key |
VT52 mode |
ANSI mode w/cursor
key mode reset |
ANSI mode w/cursor
key mode set |
| UP | <ESC>A | <ESC>[A | <ESC>OA |
| DOWN | <ESC>B | <ESC>[B | <ESC>OB |
| RIGHT | <ESC>C | <ESC>[C | <ESC>OC |
| LEFT | <ESC>D | <ESC>[D | <ESC>OD |
etx
# -- Graphics Characters ------------------------------------------------------------
cat >> $RES << etx
Special Graphics Characters
If the Special Graphics set is selected, the graphics for ASCII codes
0137 through 0176 will be replaced according to the following table (see the
SCS control sequence).
etx
awk -f awk.table.graphic < Table.Graphic >> $RES
cat >> $RES << etx
NOTE 1: Codes 0152-0156 and 0164-0170 are used to draw rectangular grids" each
piece of this set is contiguous with other so the lines formed will be
unbroken.
NOTE 2: Codes 0157-0163 give better vertical resolution than dashes and
underlines when drawing graphs; using these segments, 120 x 132 resolution may
be obtained in 132 column mode with the Advanced Video Option installed.
References
This text is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Lars Dölle, 1998
etx