pcvt(4)

NAME

pcvt, vt - VT220 virtual screen system console

SYNOPSIS

device vt0
In /boot/device.hints:
hint.vt.0.at="isa"

DESCRIPTION

Overview
The pcvt driver provides a virtual screen handling system.
Probably most
important is an emulation of a wide range of DEC VT-220
functionality.
See Features for a detailed description.
The pcvt driver requires the keyboard driver atkbd to be al
so configured
in the kernel.
Features
+o Almost full DEC VT220 functionality (moving towards
VT320)
+o Completely independent virtual terminals for
MDA/HGC/CGA/EGA and VGA
+o 25, 28, 35, 40, 43 or 50x80 screen resolution for each
virtual screen
+o Fully remappable keyboard to support national keyboards
+o All VT220 character sets plus ISO Latin-1 and DEC tech
nical supported
+o VT220 downloadable character set supported when run on
EGA/VGA
+o VT220 user defined keys for each virtual terminal
+o Optional function key label support a la Hewlett-Packard
terminals
+o Display function codes functionality
+o Support for MDA, CGA, EGA and VGA display adaptors
+o Support for 132 column operation on some VGA chipsets
+o X Window Support for XFree86 (requires XSERVER to be de
fined)
What it cannot:
+o No double wide/high characters
+o No softscroll
+o No inverse background
+o No VT220 printer output support
+o No VT52 support at all
+o No 8-bit controls
+o Only limited AT-keyboard (84 keys) support
Scrollback
Each virtual pcvt virtual terminal has 8 pages of memory at
tached which
are used as a scrollback buffer. By using SHIFT-PageUp and SHIFT-PageDown it is possible to scroll the screen back and
forward.
Configuration
The pcvt console driver is available for the Intel-based
FreeBSD operating system. It has been designed to be highly configurable
in order to
satisfy everyone's needs. The preferred configuration
method is to provide appropriate option lines within the kernel configura
tion file, possibly overriding the built-in defaults.
The following list gives a short overview of the available
configuration
options. Refer to the file i386/isa/pcvt/pcvt_conf.h in the
kernel
source tree for detailed documentation.
Note: The following conventions apply to all Boolean op
tions. If an
option value is given as 0, the option is deactivated. With
any other
value, or no value, the option is activated. If an option
is omitted, a
built-in default is assumed.
PCVT_NSCREENS
Defines the number of virtual screens.
Default: 8
PCVT_VT220KEYB
If activated, a keyboard layout resembling a DEC
VT200 (TM) is
generated. If deactivated, a mixture between VT220
and HP is
used. See the files Keyboard.VT and Keyboard.HP in
the pcvt documentation directory for a full description.
Default: off
PCVT_SCREENSAVER
Enables the builtin screensaver feature.
Default: on
PCVT_PRETTYSCRNS
If enabled, a blinking-star screensaver is used. If
disabled,
the screen is simply blanked (which might be useful
for energysaving monitors).
Default: on
PCVT_CTRL_ALT_DEL
If enabled, the key combination <Ctrl> <Alt> <Del>
invokes a CPU
reset.
Default: off
PCVT_USEKBDSEC
Do NOT override a security lock for the keyboard.
Default: on
PCVT_24LINESDEF
If enabled, the 25-line modi (VT emulation with 25
lines, and HP
emulation with 28 lines) default to 24 lines only to
provide a
better compatibility to the original DEV VT220 (TM).
Thus it
should be possible to use the terminal information
for those terminals without further changes. Note that this is a
startup
option; it is possible to toggle between the 24- and
25-lines'
display by the scon(1) utility.
Default: off
PCVT_META_ESC
If enabled, a sequence composed of <esc>, followed
by the normal
key code is emitted if a key is pressed with the
<Alt> key modifier. If disabled, then normal key code with the
value 0x80
added is sent.
Default: off
Note that there are further options available which are
mainly used for
debugging purposes or as a workaround for hardware problems.
They are
found in i386/isa/pcvt/pcvt_conf.h along with their documen
tation.
Internal Functions
The functionality described below may be accessed via
ioctl(2) system
calls with a file descriptor opened on a device node related
to the pcvt
driver. To make use of them, a program should contain the
following
line:

#include <machine/pcvt_ioctl.h>
Any parameter definitions cited below can be found in that
file.
Keyboard related functions
Three functions are related to basic keyboard hardware:

KBDRESET reset keyboard, set defaults;
KBDGTPMAT get current typematic value, pa
rameter is a
pointer to int where the values
is stored to;
KBDSTPMAT set current typematic value,
similar to above
command.
Symbolic values are available for the appropriate constants.
To specify
the initial typematic delay time, they are KBD_TPD250 for
250 ms through
KBD_TPD1000 for 1000 ms, in steps of 250 ms. The typematic
repeat rates
are KBD_TPM300, specifying 30.0 characters per second
through KBD_TPM20
for 2.0 characters per second. The intermediate values are:
30.0, 26.7,
24.0, 21.8, 20.0, 18.5, 17.1, 16.0, 15.0, 13.3, 12.0, 10.9,
10.0, 9.2,
8.6, 8.0, 7.5, 6.7, 6.0, 5.5, 5.0, 4.6, 4.3, 4.0, 3.7, 3.3,
3.0, 2.7,
2.5, 2.3, 2.1, 2.0 characters per second.

KBDGREPSW get key repetition switch, and
KBDSREPSW set key repetition switch
again take a pointer to int as argument. They manipulate
the drivers
internal keyboard repetition flag, possible values are:
KBD_REPEATOFF or
KBD_REPEATON.

KBDGLEDS get LED state, and
KBDSLEDS set LED state manipulate the
keyboard indica
tors, but do not influence the
drivers idea
of lock key state.
The int where the argument points to may have the values
KBD_SCROLLLOCK,
KBD_NUMLOCK, KBD_CAPSLOCK, which may be used in any conjunc
tion.

KBDGLOCK gets state of SCROLL,NUM,CAPS,
and
KBDSLOCK sets state of SCROLL,NUM,CAPS +
LEDs
should be used in a same manner to get/set the drivers in
ternal LED
flags.
Keyboard remapping
One important feature of the pcvt driver is its ability to
overload the
built in key definition.

KBDGCKEY get current key values,
KBDSCKEY set new key assignment values,
and
KBDGOKEY get original key assignment val
ues
arrange those functions. The take a pointer to a struct
kbd_ovlkey as
argument as described below. In addition,

KBDRMKEY removes a key assignment, taking
a pointer to
an int as argument which con
tains the
affected key number;
KBDDEFAULT removes all key assignments.
struct kbd_ovlkey /* complete definition of a
key */
{
u_short keynum; /* the key itself
*/
u_short type; /* type of key, see
below */
u_char subu; /* subtype, ignored
on write */
char unshift[KBDMAXOVLKEYSIZE+1]; /* emitted string,
unshifted */
u_char subs; /* subtype, ignored
on write */
char shift[KBDMAXOVLKEYSIZE+1]; /* emitted string,
shifted */
u_char subc; /* subtype, ignored
on write */
char ctrl[KBDMAXOVLKEYSIZE+1]; /* emitted string,
control */
u_char suba; /* subtype, ignored
on write */
char altgr[KBDMAXOVLKEYSIZE+1]; /* emitted string,
altgr */
};
The appropriate values for the type field are:

KBD_NONE no function, key is disabled,
KBD_SHIFT keyboard shift,
KBD_META alternate shift, sets bit8 to
ASCII code,
KBD_NUM numeric shift, keypad numeric /
application
mode,
KBD_CTL control code generation,
KBD_CAPS caps shift - swaps case of let
ter,
KBD_ASCII ASCII code generating key,
KBD_SCROLL stop output,
KBD_FUNC function key,
KBD_KP keypad keys,
KBD_BREAK ignored,
KBD_ALTGR AltGr translation feature,
KBD_SHFTLOCK shift lock,
KBD_CURSOR cursor keys, and
KBD_RETURN ``Return'' or ``Enter'' keys.
The subtype field contains one of the values

KBD_SUBT_STR key is bound to a string, or
KBD_SUBT_FNC key is bound to a function.
Downloadable character set interface
EGA and VGA video adaptors provide the capability of down
loadable software fonts. Since the `native character set' of any IBM
compatible PC
video board does not allow the full interpretation of DEC
multinational
character set or ISO Latin-1 (ISO 8859-1), this might be
very useful for
a U**X environment.

VGASETFONTATTR set font attr, and
VGAGETFONTATTR get font attr
are used to manipulate the drivers information about a down
loaded font.
The take a pointer to a struct vgafontattr as argument:
struct vgafontattr {
int character_set; /* VGA character set */
int font_loaded; /* Mark font loaded or un
loaded */
int screen_size; /* Character rows per screen
*/
int character_scanlines; /* Scanlines per character
1 */
int screen_scanlines; /* Scanlines per screen - 1
byte */
};
Each character of each font is to be downloaded with

VGALOADCHAR load vga char,
taking a pointer to struct vgaloadchar as its argument:
struct vgaloadchar {
int character_set; /* VGA character set to load
into */
int character; /* Character to load */
int character_scanlines; /* Scanlines per character */
u_char char_table[32]; /* VGA character shape table */
};
The field character_set takes the values CH_SET0, CH_SET1,
CH_SET2,
CH_SET3 on EGA's or VGA's. Since VGA's might have up to
eight simultaneously loaded fonts, they can take CH_SET4, CH_SET5, CH_SET6,
or CH_SET7,
too.
Note that there is a dependence between the font size and a
possible
screen height (in character rows), depending on the video
adaptor used:
Screen size (rows) on: EGA VGA
Font size
8 x 8 43 50
8 x 10 35 40
8 x 14 25 28
8 x 16 not 25
applicable
General screen manipulation commands

VGACURSOR sets cursor shape,
taking a pointer to the following structure as argument:
struct cursorshape {
int screen_no; /* screen number for which to set,
*/
/* or -1 to set on current active screen
*/
int start; /* top scanline, range 0... Character
Height - 1 */
int end; /* end scanline, range 0... Character
Height - 1 */
};

VGASETSCREEN set screen info, and
VGAGETSCREEN get screen info,
provide an interface to some general driver internal vari
ables which
might modify the behaviour of the screens, or which might
simply be used
to force the driver to switch to one certain screen. Their
argument is a
pointer to the structure:
struct screeninfo {
int adaptor_type; /* type of video adaptor installed
*/
/* read only, ignored on write
(yet!) */
int totalfonts; /* no of downloadable fonts
*/
/* read only, ignored on write
*/
int totalscreens; /* no of virtual screens
*/
/* read only, ignored on write
*/
int screen_no; /* screen number, this was got from
*/
/* on write, if -1, apply
pure_vt_mode */
/* and/or screen_size to current
screen*/
/* else to screen_no supplied
*/
int current_screen; /* screen number, which is dis
played. */
/* on write, if -1, make this screen
*/
/* the current screen, else set cur
rent*/
/* displayed screen to parameter
*/
int pure_vt_mode; /* flag, pure VT mode or HP/VT mode
*/
/* on write, if -1, no change
*/
int screen_size; /* screen size
*/
/* on write, if -1, no change
*/
int force_24lines; /* force 24 lines if 25 lines VT
mode */
/* or 28 lines HP mode to get pure
*/
/* VT220 screen size
*/
/* on write, if -1, no change
*/
int vga_family; /* if adaptor_type = VGA, this re
flects*/
/* the chipset family after a read
*/
/* nothing happens on write ...
*/
int vga_type; /* if adaptor_type = VGA, this re
flects*/
/* the chipset after a read
*/
/* nothing happens on write ...
*/
int vga_132; /* set to 1 if driver has support
for */
/* 132 column operation for chipset
*/
/* currently ignored on write
*/
};
Its field pure_vt_mode may take the values M_HPVT for a
mixed VTxxx and
HP Mode, with function key labels and a status line, or
M_PUREVT for only
VTxxx sequences recognized, with no labels.

VGASETCOLMS sets the number of columns for
the current
screen,
its parameter is a pointer to an integer containing either a
value of 80,
or a value of 132. Note that setting the number of columns
to 132 is
only supported on some VGA adaptors. Any unsupported num
bers cause the
ioctl to fail with errno (see intro(2)) being set to EINVAL.
VGA color palette interface
Only on VGA adaptors, there is a color palette register at
the output.
It is responsible for the red, green and blue output voltage
provided for
each of the 256 internal color codes, each lying in the
range of 0
through 63 (with 63 representing the brightest value for a
base color).
Thus, these adaptors map each color code to a color of a
``palette'' out
of 262144 colors. The commands

VGAREADPEL read VGA palette entry, and
VGAWRITEPEL write VGA palette entry
establish an interface to these palette registers. Their
argument is a
pointer to:
struct vgapel {
unsigned idx; /* index into palette, 0 .. 255 valid
*/
unsigned r, g, b; /* RGB values, masked by VGA_PMASK
(63) */
};
Driver identification

VGAPCVTID returns information if the cur
rent compiled
in driver is pcvt and its major
and minor
revision numbers. the call is
taking a
pointer to the following struc
ture as argument:
struct pcvtid {
#define PCVTIDNAMELN 16 /* driver id
string length */
char name[PCVTIDNAMELN]; /* driver name, ==
PCVTIDSTR */
#define PCVTIDNAME "pcvt" /* driver id
string */
int rmajor; /* revision number,
major */
#define PCVTIDMAJOR 3
int rminor; /* revision number,
minor */
#define PCVTIDMINOR 00
};

VGAPCVTINFO returns information if the cur
rent compiled
in driver is pcvt and its com
pile time
options. the call is taking a
pointer to the
following structure as argument:
struct pcvtinfo {
u_int opsys; /* PCVT_xxx(x)BSD */
#define CONF_UNKNOWNOPSYS 0
#define CONF_386BSD 1 /* unsupported !!!
*/
#define CONF_NETBSD 2
#define CONF_FREEBSD 3
u_int opsysrel; /* Release for NetB
SD/FreeBSD */
u_int nscreens; /* PCVT_NSCREENS */
u_int scanset; /* PCVT_SCANSET */
u_int updatefast; /* PCVT_UPDATEFAST
*/
u_int updateslow; /* PCVT_UPDATESLOW
*/
u_int sysbeepf; /* PCVT_SYSBEEPF */
u_int pcburst; /* PCVT_PCBURST */
u_int kbd_fifo_sz; /* PCVT_KBD_FIFO_SZ
*/
/* config booleans */

u_long compile_opts; /*
PCVT_xxxxxxxxxxxxxxx */
};
Screen saver
Depending on the configuration of a pcvt driver, there might
be a simple
screen saver available. It is controlled by the command

VGASCREENSAVER set timeout for screen saver in
seconds; 0
turns it off,
taking a pointer to an integer as argument. Despite its
command name,
this is available on any kind of adaptor if configured in by
the
config(8) option ``PCVT_SCREENSAVER''
Compatibility commands for USL-style VT's
pcvt supports a subset of the USL-style commands used to
control the virtual terminal interface. This feature is mainly intended to
allow
XFree86 to switch between virtual screens even when running
an X server.
They are ugly with respect to the implied semantics (i.e.,
they break
Berkeley semantics). See the file i386/include/pcvt_ioctl.h
for their
documentation.

FILES

/usr/include/machine/pcvt_ioctl.h Definitions for ioctl(2)
function
calls
/dev/ttyv?
/dev/console Device nodes to access
the pcvt driver
i386/isa/pcvt/pcvt_conf.h (relative to the kernel
source tree)
Documents the various
compile-time
options to tailor pcvt.

SEE ALSO

cursor(1), loadfont(1), scon(1), intro(2), ioctl(2),
atkbd(4),
keyboard(4), config(8), ispcvt(8)

HISTORY

The pcvt driver has been developed for and contributed to
386BSD 0.1.
Since then pcvt has become a standard part of FreeBSD, NetB
SD and
OpenBSD. Since FreeBSD 5.0, pcvt is FreeBSD specific with
support for
NetBSD and OpenBSD removed to ease further maintenance.

AUTHORS

Written by Hellmuth Michaelis <hm@FreeBSD.org> with much
help from Brian
Dunford-Shore <brian@morpheus.wustl.edu> and Jorg Wunsch
<joerg@FreeBSD.org>.
This driver is based on several people's previous work, no
tably the historic pccons(4) implementation by William Jolitz
<ljolitz@cardio.ucsf.edu> and Don Ahn, and the keyboard map
ping code from
Holger Veit <veit@first.gmd.de>.

BUGS

At least one left.
BSD March 26, 2000

BSD

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