FreeBSD Man Pages

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 also 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 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

   Scrollback
     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.

   Configuration
     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.
	     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 doc-
	     umentation 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 energy-
	     saving 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 ter-
	     minals 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 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.

     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
				 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 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
     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 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
				 affected key number;
	   KBDDEFAULT		 removes all key assignments.

	 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 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:
     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,
     too.

     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
				     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 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  */
			     /* 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 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-
				 ment:

     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
     #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
     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.

HISTORY

     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.

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>.
     keyboard(4), config(8), ispcvt(8)

BUGS

     At least one left.

FreeBSD 5.4			March 26, 2000			   FreeBSD 5.4

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