kbd/docs/doc/console.docs

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From: Peter Jones <thanatos@drealm.org>
Newsgroups: comp.os.linux.announce
Subject: Linux Console Terminal Documentation
Followup-To: comp.os.linux.misc
Date: Sat, 30 Sep 95 16:37:05 GMT
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I thought I'd do "something" for the Linux community (apart from
co-authoring drealmBBS :-)).

So, here's my first (and maybe only) issue of the Linux Console Driver
documentation.  Anyone wanting to take this on as a support task, feel
free - I _really_ don't have time to keep up with new 1.3.x kernels.

- -- Peter

Linux Console Driver
====================
====================
(Everything you ever wanted to know but couldn't be bothered to look in the
source for.)

Author: Peter L Jones <thanatos@drealm.org>
~Date: Wed Sep 27 19:12:25 BST 1995
Kernel: 1.2.13
Addendum for: 1.3.28


General Processing
==================
I don't use UTF.  I've only covered it to the extent I can fathom from the
source.

I've not documented "hardware scrollback".

In UTF mode, once a complete character is assembled, it is translated.

Otherwise, the character then has its top bit set if requested and is then
translated.

A glyph is to be displayed if
	* we've assembled a complete UTF character
	* we translated it okay
	* it's not a control character, or we're displaying control
	  characters
Otherwise, it might be a control character.
Otherwise it's ignored.


Glyphs
======
These are characters that make a mark on the display.

You can never display the glyph for char(27) by transmitting ESC.

You cannot display glyphs for any character in the Control Characters table,
unless enabled.

If there is a "pending newline"
	a crlf sequence is issued prior to the glyph.

If we're in "insert mode",
	the rest of the line is shifted right; the character in the
	last column is lost.

The glyph is then displayed.

If the cursor is in the last column,
	If automatic margins are turned on,
		the "pending newline" state is set
	otherwise,
		the next glyph can overwrite this one.
Otherwise the cursor is advanced.


Control Characters
==================
Control characters can occur during ESCape sequence processing.

^g		bell - make a tone on the console speaker
^h		bs - cursor to previous character (backspace)
		(will not wrap to previous line)
^i		tab - cursor to next tab position
^j ^k ^l	lf - cursor to next line, scroll if end of scrolling region
		(linefeed); if CRLF mode select, cr as well
^m		cr - cursor to start of current line (carriage return)
^n		charset 1, translate table G1, display control characters
		as glyphs
^o		charset 0, translate table G0, don't display control
		characters as glyphs
{-- "charset" sets the current translate table; e.g. ^n sets charset
1, translate table G1, display control characters as glyphs - followed by
^[[10m would leave G1 in effect but disable display of control characters as
glyphs and display setting the top bit of glyphs --}

^x ^z		cancel any ESCape sequence in progress
^[		begin an ESCape sequence
^?		"delete" - ignored
128+^[		begin a CSI sequence


ESCape Sequences
================
^[[		begin a CSI sequence
^[%		begin a UTF control sequence
^[(		begin a set G0 sequence
^[)		begin a set G1 sequence
^[#		begin a DEC test sequence
^[E		cr, lf
^[M		ri - cursor up, reverse scroll if top of scrolling region
		(reverse index)
^[D		lf
^[H		set tab in the current column
^[Z		request for terminal ID (response is ^[[?6c - VT102)
^[7		store cursor position
^[8		restore cursor position
^[c		reset terminal completely
^[>		Keypad is numeric (normal)
^[=		Keypad is application (act as function keys)


CSI sequences
=============

There are two formats.  Function keys are indicated by CSI [ and are dealt
with later.  The general format is CSI (i.e. ^[[), zero to 16 parameters and
a character to indicate the function being performed.  E.g ^[[1;43;37m.

Missing parameters are defaulted.  Screen co-ordinates and movements start
at and default to 1 (unless otherwise stated).  Parameters are named par1,
par2 etc in the following descriptions.

CSI h and CSI l can have an optional ? after the CSI and before any
parameters.  This indicates "DEC Private" modes.  {-- Other manufacturers
use different characters to select their private modes - Linux doesn't
support any but DEC. --}

CSI h		Set Mode sequence
CSI l		Clear Mode sequence
CSI n		Request report:
		par1 = 5 - Status report: response is ^[[0n (terminal okay)
		par1 = 6 - Cursor report: response is ^[[y;xR - where y is
		relative if origin mode is selected
CSI A		Cursor Up by par1 lines
CSI F		Cursor Up by par1 lines, and to start of line
CSI B CSI e	Cursor Down by par1 lines
CSI E		Cursor Down by par1 lines, and to start of line
CSI C CSI a	Cursor Right by par1 characters
CSI D		Cursor Left by par1 characters
CSI d		Set cursor vertical position to par1
CSI G CSI `	Set cursor horizonal position to par1
CSI H CSI f	Set cursor vertical position to par2 and horizontal position
		to par1
CSI L		Insert par1 lines
CSI M		Delete par1 lines
CSI @		Insert par1 characters
CSI P		Delete par1 characters
CSI X		Erase par1 characters (wraps around line ends)
CSI J		Screen Erase sequence:
		par1 = 0 - erase from cursor to end of display
		par1 = 1 - erase from start of display to cursor
		par1 = 2 - erase whole display
CSI K		Line Clear sequence:
		par1 = 0 - erase from cursor to end of line
		par1 = 1 - erase from start of line to cursor
		par1 = 2 - erase whole line
CSI c		If par1 = 0 (default), requests terminal ID
		(response is ^[[?6c - VT102)
CSI g		Clear tabs:
		par1 = 0 - Clears tab at the current column
		par1 = 3 - Clears all tabs
CSI q		Set LEDs = par1 indicates which LED to turn on -
		0 - none, 1 - , 2 - , 3 - .
CSI r		Set scrolling region
		par1 - top, default and minimum 1, must be less than par2
		par2 - bottom, default and maximum end of display
CSI s		Store cursor position
CSI u		Restore cursor position
CSI m		Character Rendition sequence
CSI ]		setterm(1) command sequence


Set and Clear Mode Sequences
- ----------------------------
CSI h sets modes; CSI l clears modes.  There are two sets of modes -
ANSI standard and DEC private.

ANSI modes:
3	Monitor (display control characters)
4	Insert
20	CRLF

DEC modes:
1	Cursor keys as application keys (send ^[Ox as appl, ^[[x as normal)
3	80 (off) or 132 (on) columns
5	Inverse video
6	Origin mode (and go to origin)
7	Autowrap (right margin)
8	Autorepeat
9	Mouse reports #1
25	Cursor visible
1000	Mouse reports #2


Character Rendition Sequences
- -----------------------------
Each parameter is actioned in order.  You cannot get bright backgrounds
(rather, I can't).  {-- On SVR4, attribute code 6 is used for bright
background, if I remember correctly --}

0	default (intensity normal, underline off, blink off, normal video,
	default colours (which start as white on black))
1	intensity bold
2	intensity dim
4	underline on
5	blink on
7	reverse video
10	restore translate table, turn off display of control chars, don't
	set the "top" bit of glyphs displayed
11	disable the translate table, display control chars as glyphs, don't
	set the "top" bit of glyphs displayed
12	disable the translate table, display control chars as glyphs,
	set the "top" bit of glyphs displayed
21 22	intensity normal
24	underline off
25	blink off
27	normal video
38	underline on, set foreground colour to default
39	underline off, set foreground colour to default
49	set background colour to default
30-37	set foreground colour (0-black, 1-red, 2-green, 3-brown, 4-blue,
	5-magenta, 6-cyan, 7-white)
40-47	set background colour


Setterm Commmand Sequences
- --------------------------
The command is in par1, followed by parameters.

1	Set underline colour - par2 is 0 to 15, which is 0 to 7 as above,
	plus bold versions
2	Set dim colour - par2 as above
8	Store current attributes as defaults (so that CSI 0 m restores to
	them)
9	Set blanking interval to par2 minutes (max one hour)


UTF Control Sequences
=====================
^[%@		Turn off UTF
^[%G ^[%8	Turn on UTF (^[%8 is deprecated)


G0/G1 Sequences
===============
There are two character sets, known as G0 and G1.  G0 is the default
character set.  Each can be set to one of four mappings.  The mappings, and
the sequences to select them, are:

 G0   G1  Map  Name
- ---- ---- ---  ----
^[(B ^[)B  0   Normal Map (default G0 map)
^[(0 ^[)0  1   Graphics Map (default G1 map)
^[(U ^[)U  2   Null Map
^[(K ^[)K  3   User Map

The maps themselves are defined in "consolemap.c".  "Normal Map" translates
the standard IBM PC ROM character set to standard 8-bit ISO Latin-1. 
"Graphics Map" translates to the VT100 character set in graphics mode. 
"Null Map" passed the ROM characters straight through, except BS, CR, LF,
LL, SO, SI and ESC.  "User Map" is available to be changed in the source or
by mapscrn(8).


DEC Test Sequences
==================
Only one test, ^[#8, is defined.  This fills the display with the character
'E' to allow the display to be centred.


Addendum
========
The console driver changed in 1.3.x.  This documents the changes between
1.2.13 and 1.3.28.

Each virtual console gains a palette, which defines the actual colours used
on the display (so you can get yellow rather than brown, for example).

Font support is enhanced.

In addition to ESC, some other control characters cannot have their glyphs
displayed - ^@ ^H ^J ^L ^M ^N ^O ^[.

Hardware scrollback has been enhanced.

The "Normal Map" has been renamed "Latin 1 Map" (LAT1_MAP).

UTF support has been enhanced.

(UTF mode can be used to display the excluded control characters - display
UTF character 0xF0cc, where cc is the hex code of the position in the ROM
character set to display.)

A new set of Nonstandard Sequences is defined, prefixed by ESC ].  (setterm
commands are still CSI ].)

Colour palette support is added.

512 byte font support is added.

Font height support allows the screen to resize to fit the font.

Nonstandard Sequences
- ---------------------
^[]P	Set palette
	Seven parameters are collected
	par1 is the palette element to redefine
	par2, par3 set the red component
	par4, par5 set the green component
	par6, par7 set the blue component
^[]R	Resets the default palette


- --
Send comp.os.linux.announce submissions to: linux-announce@news.ornl.gov
PLEASE remember a short description of the software.

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From: Peter Jones <thanatos@drealm.org>
Newsgroups: comp.os.linux.misc
Subject: Re: Linux Console Terminal Documentation
Date: 30 Sep 1995 20:12:27 +0100
Organization: drealm conference system +44 (0)181 568 2204
Lines: 35
Message-ID: <44k4qr$6aj@drealm.drealm.org>
References: <cola-liw-812479025-13056-1@oravannahka.helsinki.fi>
X-NNTP-Posting-Host: drealm.demon.co.uk
X-Newsreader: TIN [version 1.2 PL2]

I (thanatos@drealm.org) wrote, in col-announce:
[chop chop]
: Nonstandard Sequences
: - ---------------------
: ^[]P	Set palette
: 	Seven parameters are collected
: 	par1 is the palette element to redefine
: 	par2, par3 set the red component
: 	par4, par5 set the green component
: 	par6, par7 set the blue component
: ^[]R	Resets the default palette


This should read (i.e. it makes sense...) like this:

Nonstandard Sequences
---------------------
^[]P	Set palette
	Seven hex digits should follow (0-9, a-f, A-F):
	1 is the palette element to redefine
	2*16 + 3 set the red component
	4*16 + 5 set the green component
	6*16 + 7 set the blue component
^[]R	Resets the default palette


Hope that helps...

(One day my "other" linux box (crash-n-burn...) will have colour...)

-- Peter
-- 
Drealm Conference System -- (+44) 181 568 2204 (V.FC)
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