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PCVT(4)                FreeBSD 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 configuration method is to pro-
     vide appropriate option lines within the kernel configuration file, pos-
     sibly 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 options.  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.

             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
             option; it is possible to toggle between the 24- and 25-lines'
             display 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
     internal 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
                                 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
           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 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

     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 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 current compiled
                                 in driver is pcvt and its 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 its compile 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 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, 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 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
                                        options to tailor pcvt.

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

     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 <>.

     At least one left.

FreeBSD 6.2                     March 26, 2000                     FreeBSD 6.2


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