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PCVT(4)			 BSD Kernel Interfaces Manual		       PCVT(4)

     pcvt, vt -- VT220 virtual screen system console

     device vt0

     In	/boot/device.hints:"isa"

     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 also configured
     in	the kernel.

     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 technical 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 defined)

     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

     Each virtual pcvt virtual terminal	has 8 pages of memory attached which
     are used as a scrollback buffer.  By using	SHIFT-PageUp and
     SHIFT-PageDown it is possible to scroll the screen	back and forward.

     The pcvt console driver is	available for the Intel-based FreeBSD operat-
     ing system.  It has been designed to be highly configurable in order to
     satisfy everyone's	needs.	The preferred way for those configurations is
     to	provide	appropriate options lines within the config file, possibly
     overriding	the built-in default values.

     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 the Boolean options.	If an
     option is given with no value, a value of 1 (activated) is	substituted.
     If	an option value	is given as 0, this options is deactivated.  Any other
     value is substituted by 1,	too.  If an option is omitted, a built-in de-
     fault is assumed.

	     Defines the number	of virtual screens.

	     Default: 8

	     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 doc-
	     umentation	directory for a	full description.

	     Default: off

	     Enables the builtin screensaver feature.

	     Default: on

	     If	enabled, a blinking-star screensaver is	used.  If disabled,
	     the screen	is simply blanked (which might be useful for energy-
	     saving monitors).

	     Default: on

	     If	enabled, the key combination <Ctrl> <Alt> <Del>	invokes	a CPU

	     Default: off

	     Do	NOT override a security	lock for the keyboard.

	     Default: on

	     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 ter-
	     minals without further changes.  Note that	this is	a startup op-
	     tion; it is possible to toggle between the	24- and	25-lines' dis-
	     play by the scon(1) utility.

	     Default: off

	     If	enabled, a sequence composed of	<esc>, followed	by the normal
	     key code is emitted if a key is pressed with the <Alt> key	modi-
	     fier.  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 documentation.

   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

	   #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, parameter	is a
				 pointer to int	where the values is stored to;
	   KBDSTPMAT		 set current typematic value, similar to above

     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 in-
     ternal keyboard repetition	flag, possible values are: KBD_REPEATOFF or

	   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 conjunction.

	   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 internal LED

     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 values

     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 contains the af-
				 fected	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
	   KBD_CTL		 control code generation,
	   KBD_CAPS		 caps shift - swaps case of letter,
	   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 downloadable soft-
     ware 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 downloaded 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 unloaded */
	 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 simultane-
     ously loaded fonts, they can take CH_SET4,	CH_SET5, CH_SET6, or CH_SET7,

     Note that there's 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

     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 variables 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	displayed.  */
			     /*	on write, if -1, make this screen   */
			     /*	the current screen, else set current*/
			     /*	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 reflects*/
			     /*	the chipset family after a read	    */
			     /*	nothing	happens	on write ...	    */
	 int vga_type;	     /*	if adaptor_type	= VGA, this reflects*/
			     /*	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

     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 numbers cause the
     ioctl to fail with	errno (see intro(2)) being set to EINVAL.

     VGA color palette interface

     Only on VGA adaptors, there's 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 current compiled
				 in driver is pcvt and it's major and minor
				 revision numbers. the call is taking a
				 pointer to the	following structure as argu-

     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 current compiled
				 in driver is pcvt and it's compile time op-
				 tions.	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 NetBSD/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, their 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 of 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 vir-
     tual 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

     /usr/include/machine/pcvt_ioctl.h	Definitions for	ioctl(2) function


     /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 op-
					tions to tailor	pcvt.

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

     Written by	Hellmuth Michaelis <> with much help from	Brian
     Dunford-Shore <> and Jorg Wunsch

     This driver is based on several people's previous work, notably the his-
     toric pccons(4) implementation by William Jolitz
     <> and Don Ahn, and	the keyboard mapping code from
     Holger Veit <>.

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

     At	least one left.

BSD				March 26, 2000				   BSD


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