.TH CONSOLE 4
.SH NAME
console, keyboard, kbd, kbdaux, log, profile, vga \- system console
.SH DESCRIPTION
The console device driver manages a series of devices related to the main
user interface:  The system screen and the keyboard.  These two together are
named "the Console".
.SS "The Screen"
The screen of a PC can be managed by a Monochrome Display Adapter, a
Hercules card, a Color Graphics Adapter, an Enhanced Graphics Adapter,
or a Video Graphics Array.  To the console driver these devices are
seen as a block of video memory into which characters can be written to
be displayed, an I/O register that sets the video memory origin to the
character that is to be displayed on the top-left position of the
screen, and an I/O register that sets the position of the hardware
cursor.  Each character within video memory is a two-byte word.  The low
byte is the character code, and the high byte is the "attribute byte",
a set of bits that controls the way the character is displayed,
character and background colours for a colour card, or
intensity/underline/reverse video for monochrome.
.PP
These are the characteristics of the adapters in text mode:
.PP
.RS
.nf
.ta +15n +15n
Adapter	Usable memory	Mono/Colour
.ta +1n +15n +15n
	MDA	4K	M
	Hercules	4K	M
	CGA	16K	C
	EGA	32K	M or C
	VGA	32K	M or C
.fi
.RE
.PP
MDA and Hercules are the same to the console driver, because the graphics
mode of the Hercules is of no use to Minix.  EGA and VGA are also mostly
seen as the same in text mode.  An EGA adapter is either a monochrome or a
colour device depending on the screen attached to it.  A VGA adapter can run
in either monochrome or colour (grayscale) mode depending on how the Boot
Monitor has initialized it.
.PP
The driver uses the video origin to avoid copying the screen contents when
scrolling up or down.  Instead the origin is simply moved one line.  This is
named "hardware scrolling", as opposed to copying memory: "software
scrolling".
.PP
The video origin is also used to implement several virtual consoles inside
the video memory of the adapter.  Each virtual console gets a segment of
video memory.  The driver chooses which console to display by moving the
video origin.  Note that an MDA or Hercules adapter can only support one
console.  CGA can support up to four 80x25 consoles, and EGA and VGA can
have eight.  It is best to configure one less console to leave some video
memory free so that hardware scrolling has some space to work in.
.PP
Character codes are used as indices into a display font that is stored in the
adapter.  The default font is the IBM character set, which is an ASCII
character set in the low 128 codes, and a number of mathematical, greek,
silly graphics, and accented characters in the upper 128 codes.  This font
is fixed in the MDA, Hercules and CGA adapters, but can be replaced by a
user selected font for the EGA and VGA adapters.
.PP
The Minix-vmd console driver assumes ISO Latin-1 character codes and
translates them to the IBM character set as well as possible.  This
translation is disabled when a font is loaded.
.PP
A number of control characters and escape sequences are implemented by the
driver.  The result is more or less compatible with the X11 terminal
emulation program
.B xterm
and the VT100 terminal,
and upward compatible with the standard Minix console and the ANSI standard
terminal.  The
.BR termcap (5)
type is the same as that of
.BR xterm .
Normal characters written to the console are displayed at the cursor
position and the cursor is advanced one column to the right.  If an entire
line is filled then the cursor wraps to the first column of the next line
when the next character must be displayed.  The screen is scrolled up if
needed to start a new line.  Some characters have special effects when sent
to the console.  Some even have arguments in the form of comma separated
decimal numbers.  These numbers default to the lowest possible value when
omitted.  The top-left character is at position (1, 1).  The following
control characters and escape sequences are implemented by the console:
.PP
.ta +10n +20n
Sequence	Name	Function
.in +31n
.ti -30n
^@	Null	Ignored (padding character)
.ti -30n
^G	Bell	Produce a short tone from the speaker
.ti -30n
^H	Backspace	Move the cursor back one column, wrapping from the
left edge up one line to the right edge
.ti -30n
^I	Horizontal Tab	Move to the next tab stop, with each tab stop at
columns 1, 9, 25, etc.  Wrap to the next line if necessary.
.ti -30n
^J	Line Feed	Move one line down, scrolling the screen up if
necessary
.ti -30n
^K	Vertical Tab	Same as LF
.ti -30n
^L	Form Feed	Same as LF
.ti -30n
^M	Carriage Return	Move to column 1
.ti -30n
^N	Shift Out	Ignored
.ti -30n
^O	Shift In	Ignored
.ti -30n
^[	Escape	Start of an escape sequence
.ti -30n
^[D	Index	Same as LF
.ti -30n
^[E	Next Line	Same as LF
.ti -30n
^[M	Reverse Index	Move one line up, scrolling the screen down if
necessary
.ti -30n
^[c	Full Reset	Clear the screen, home the cursor, and reset all
attributes
.ti -30n
^[[\fIn\fPA	Cursor Up	Move the cursor up \fIn\fP lines
.ti -30n
^[[\fIn\fPB	Cursor Down	Move the cursor down \fIn\fP lines
.ti -30n
^[[\fIn\fPC	Cursor Forward	Move the cursor right \fIn\fP columns
.ti -30n
^[[\fIn\fPD	Cursor Backward	Move the cursor left \fIn\fP columns
.ti -30n
^[[\fIm\fP;\fIn\fPH	Cursor Position	Move the cursor to line \fIm\fP,
column \fIn\fP
.ti -30n
^[[\fIs\fPJ	Erase in Display	Clear characters as follows:
.br
\fIs\fP = 0: From cursor to end of screen
.br
\fIs\fP = 1: From start of screen to cursor
.br
\fIs\fP = 2: Entire screen
.ti -30n
^[[\fIs\fPK	Erase in Line	Clear characters as follows:
.br
\fIs\fP = 0: From cursor to end of line
.br
\fIs\fP = 1: From start of line to cursor
.br
\fIs\fP = 2: Entire line
.ti -30n
^[[\fIn\fPL	Insert Lines	Insert \fIn\fP blank lines
.ti -30n
^[[\fIn\fPM	Delete Lines	Delete \fIn\fP lines
.ti -30n
^[[\fIn\fP@	Insert Characters	Insert \fIn\fP blank characters
.ti -30n
^[[\fIn\fPP	Delete Characters	Delete \fIn\fP characters
.ti -30n
^[[\fIn\fPm	Character Attribute	Set character attribute as follows:
.br
\fIn\fP = 0: Normal (default) attribute
.br
\fIn\fP = 1: Bold (mono) / Yellow (colour)
.br
\fIn\fP = 4: Underline (M) / Light green (C)
.br
\fIn\fP = 5: Blinking (M) / Magenta (C)
.br
\fIn\fP = 7: Reverse Video
.br
\fIn\fP = 30: Black foreground colour
.br
\fIn\fP = 31: Red
.br
\fIn\fP = 32: Green
.br
\fIn\fP = 33: Orange
.br
\fIn\fP = 34: Blue
.br
\fIn\fP = 35: Magenta
.br
\fIn\fP = 36: Light blue
.br
\fIn\fP = 37: White
.br
\fIn\fP = 40 \- 47: Same for background colour
.ti -30n
^[[?3l		Switch console to 80 column mode and reset.  A vertical line
of `|' characters will appear if the console is in a mode with more than 80
columns.  That line is now the right edge of the screen
.ti -30n
^[[?3h		Switch console to full width and reset.
.ti -30n
^[]2;\fIt\fP^G		Enable the status line and display the string \fIt\fP
on it, any control code ends \fIt\fP, but ^G is the proper code
.in -31n
.PP
The console interprets and then ignores several other escape sequences for
compatibility reasons.  Only the ignored control characters are listed
above.
.PP
The console devices implements the following ioctls to copy from or to the
font memory on EGA and VGA adapters:
.PP
.RS
.BI "ioctl(" fd ", TIOCGFON, u8_t " font "[256][32]);"
.br
.BI "ioctl(" fd ", TIOCSFON, u8_t " font "[256][32]);"
.RE
.PP
Font memory consists of 256 character definitions of 32 lines per character
and 8 pixels per line.  The first line is the topmost line of the character.
The leftmost pixel is lit if the most significant bit of a line is set, etc.
How many lines are used depends on the current video mode.  The 80x25 video
mode used by Minix has an 8x16 character cell, 80x28 has 8x14 characters,
and 132x43 has 8x8 characters.  The boot variable
.B console
is used by both the Boot Monitor and the console driver to set the video
mode, software scrolling on/off, and VGA screen blank timeout.  See
.BR boot (8).
.SS "The Keyboard"
The keyboard produces key codes for each key that is pressed.  These keys
are transformed into character codes or sequences according to the current
keyboard translation table.  The format of this table is described in
.BR keymap (5).
The character codes can be read from the console device unless they map to
special hotkeys.  The hotkeys are represented by \fB^"\fIname\fB"\fR
like things in the keyboard tables.  The hotkey names and the keys they are
by default bound to are as follows:
.PP
.ta +9n +17n
Name	Key	Function
.in +27n
.ti -26n
reboot	CTRL\-ALT\-DEL	Send an abort signal to process 1 (init).  Init then
halts the system
.ti -26n
reboot	CTRL\-ALT\-KP-.	Likewise for keypad period
.ti -26n
pdmp	CTRL\-F1	Process table dump
.ti -26n
mdmp	CTRL\-F2	Show memory map
.ti -26n
scroll	CTRL\-F3	Toggle software/hardware scrolling
.ti -26n
serdbug	CTRL\-F4	Select serial line to copy debug messages to
.ti -26n
netstat	CTRL\-F5	Show network statistics
.ti -26n
prio	CTRL\-F6	Show scheduler priority table
.ti -26n
loadav	CTRL\-F7	Show load averages table
.ti -26n
vmdmp	CTRL\-F8	Show virtual memory statistics
.ti -26n
fpemu	CTRL\-F9	Floating point emulation toggle (does nothing as yet)
.ti -26n
debug	CTRL\-F10	Toggle kernel debug flag between 0 and 1
.ti -26n
vc0	ALT\-F1	Select virtual console 0 (/dev/console)
.ti -26n
vc1	ALT\-F2	Select virtual console 1 (/dev/ttyc1)
.ti -26n
vc\fIn\fP	ALT\-F(\fIn\fP+1)	Select virtual console \fIn\fP
(/dev/ttyc\fIn\fP)
.ti -26n
vc\-	ALT\-Left	Select previous virtual console
.ti -26n
vc+	ALT\-Right	Select next virtual console
.ti -26n
st\-	ALT\-Down	Disable the status line
.ti -26n
st+	ALT\-Up	Enable the status line
.in -27n
.PP
.\"XXX
The keyboard map is set with the
.B KIOCSMAP
ioctl whose precise implementation cannot be described here for the
author of this text has not looked at the new keymap code yet.
.SS "VGA and keyboard devices"
The
.B vga
device is used by the X11 server to map the video memory into its address
space.  Console ouput is then sent to the log device instead, and keyboard
input is no longer sent to the console but can be read as raw scan codes from
the
.B kbd
device by the X11 server.  The
.B kbdaux
is a serial input device for a PS/2 style mouse.
.SS "Log device"
The
.B log
device can be used by processes to print debug messages onto the console.
The console is a terminal type device, so it is taken from processes when a
session leader exits.  This does not happen with the log device.  Messages sent
to the log device are placed in a circular buffer whose contents can be read
from the log device and put in a log file for instance.  Several copies of
the log buffer are placed into extended memory on a system crash.  They are
retrieved if the system is immediately rebooted.
.SS "Profiling"
.\"XXX
The
.B profile
device implements two ioctls,
.BR PIOCSTART ,
to turn on kernel profiling and make profile data available to be read from
the profile device, and
.BR PIOCSTOP ,
to stop profiling.  Precise details are currently hidden within the
.BR profile
and
.BR prof_stop
utilities.
.SH "SEE ALSO"
.BR tty (4),
.BR keymap (1),
.BR keymap (5),
.BR profile (8),
.BR boot (8).
.SH NOTES
Output processing turns Line Feeds into CR LF sequences.  Don't let this
surprise you.  Either turn off output processing or use one of the synonyms
for LF.
.PP
Line Feed is changed into a CR LF sequence in canonical mode.
.PP
The mistreatment of the console and keyboard driver by Philip has not yet
reached its limit, so one can expect some changes.
.SH BUGS
Some escape sequences should provoke the console into sending identification
codes back out.  Processes may wait forever for these codes.  Only
processes that try more than the codes listed in the
.B xterm
termcap definition may be troubled by unimplemented weird features.
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)
.\" minor editing of man page by asw 07.08.96