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PCVT(4)                FreeBSD Kernel Interfaces Manual                PCVT(4)

     pcvt, vt -- PC console virtual screen system

     options "PCVT_FREEBSD=version | PCVT_NETBSD=version"
     options "PCVT_NSCREENS=number"
     options PCVT_XXXX (see Configuration below)

     device vt0 at isa?

     The pcvt driver provides a virtual screen system with several additional
     features not available in historic console drivers.  Besides the ability
     of handling multiple virtual screens, the 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
     +o   Display function codes functionality
     +o   Support for MDA, CGA, EGA and VGA display adaptors
     +o   Support for 132 column operation on VGA chipsets
     +o   X Window Support for XFree86 >= 1.2 using the pccons model, or for
         XFree86 >= 2.0 using the syscons model (requires PCVT_USL_VT_COMPAT
         to be configured)

     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 (yet)
     +o   Help you to make money...

     Each virtual pcvt virtual terminal now has 8 pages of memory attached
     which are used as a scrollback buffer (definition of SCROLLBACK_PAGES).

     By using SHIFT-PageUp and SHIFT-PageDown it is possible to scroll the
     screen back and forward.

     The pcvt console driver is currently available for the Intel-based BSD
     operating systems NetBSD/i386 (release 0.9 or higher), and FreeBSD
     (release 1.0-GAMMA or higher) .  In order to get the appropriate system
     support, one of the options PCVT_NETBSD, or PCVT_FREEBSD must be defined
     in the system's config file (see config(8)).  In addition, for the
     FreeBSD and NetBSD operating systems, it is necessary to set this option
     to the operating system's version number.  For FreeBSD this version num-
     ber must be expressed as a 3-digit number.  E. g., if you are running the
     1.0 release (which is actually version 1.0.2), you should define

     PCVT_FREEBSD = 102

     For NetBSD this version number must be expressed as 9 if you are running
     NetBSD 0.9 and anything greater than 9 for NetBSD-current (pre 1.0). It
     is recommended to use (as with FreeBSD) 100 for NetBSD 1.0 and 999 for
     NetBSD-current. E.g., if you are running the NetBSD 1.0 release, you
     should define

     PCVT_NETBSD = 100

     The pcvt driver 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.  Therefore it is possible to com-
     pile several distinct kernels with different driver behaviour on a single

     The following list gives a short overview of the available configuration
     options.  Refer to the file i386/isa/pcvt/pcvt_hdr.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
     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

             Emulate a three-button mouse via the keypad.  Useful for note-
             books when running XFree86.  See Mouse emulation below.

             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_hdr.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.

     Mouse emulation

     The mouse emulator (if configured in) fakes a three-button mouse using
     the Mouse Systems protocol.  The first pcvt device node not used by a
     virtual screen is the mouse device.  I. e., for the default value of 8
     virtual screens, /dev/ttyv0 through /dev/ttyv7 would refer to the virtual
     screens, and /dev/ttyv8 were the mouse emulator device.  The mouse emula-
     tion is turned on by pressing the <NumLock> key.  The pointer is moved by
     the numerical keypad keys, into the obvious directions.  The pointer is
     initially moved in single steps, and is accelerated after an adjustable
     time (default: 500 ms) by about 6 times.  The mouse buttons are emulated
     by three normal keys, by default the function keys <F1>, <F2>, and <F3>.
     There are two selectable flavors available: normal and ``sticky'' but-
     tons.  Normal buttons behave as expected.  ``Sticky'' buttons are noti-
     fied as button-press on the first keypress.  They ``stick'' until the key
     is pressed again (or another button-emulating key instead).  Button
     presses and releases are notified to the user by a simple ``pling'', or
     ``plong'', respectively, generated from the PC's built-in speaker.

     The following commands control the emulation.

           KBDMOUSEGET           get the current definitions, and
           KBDMOUSESET           set new definitions.

     Both accept a struct mousedefs * as the third argument to the ioctl call:

     struct mousedefs {
         int leftbutton;     /* (PC) scan code for "left button" key     */
         int middlebutton;   /* (PC) scan code for "mid button" key      */
         int rightbutton;    /* (PC) scan code for "right button" key    */
         int stickybuttons;  /* if true, the buttons are "sticky"        */
         int acceltime;      /* timeout in microseconds to start pointer */
                             /* movement acceleration                    */
         /* defaults to: scan(F1), scan(F2), scan(F3), false, 500000     */

     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 happenes 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 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
                                 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, 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

     Release 3.00 of this pcvt driver supports a subset of the USL-style com-
     mands used to control the virtual terminal interface.  This feature is
     mainly intended to allow XFree86, release 2.0 or higher, 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 seman-
     tics) and are therefore not recommended for common use.  See the file
     i386/include/pcvt_ioctl.h for their documentation.

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


     /dev/console                       Device nodes to access the pcvt driver

     i386/isa/pcvt/pcvt_hdr.h           (relative to the kernel source tree)
                                        Documents the various compile-time
                                        options to tailor pcvt.

     The pcvt driver has been developed for and contributed to 386BSD release
     0.1. Since release 3.00 explicit support is provided for NetBSD 0.9. It
     is expected that no further development on pcvt is done for 386BSD 0.1
     after release 3.00, in fact, 386BSD support was dropped with release

     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 by
     William Jolitz' <> and Don Ahn's historic
     pccons(4) implementation.

     Holger Veit <>

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

     Certainly existent.  See the file BugList in the Documentation directory
     for an up-to-date list.

   Tested Video Boards
     Manufacturer                    Chipset                 Monitor

     2theMax (?)                     ET4000                  VGA Color
     Video7 Inc.                     Video 7                 VGA Color
     Diamond Stealth VRAM            S3                      NEC 3FGx
     Trident                         TVGA 8800CS             NEC 3D
     Data General                    C&T P82C604             VGA Color
     NoName Hercules                 W86855AF                Mono
     Kyocera (Mainboard)             WD90C11                 Sony Color
     unknown                         ET3000                  NEC 3D

   Tested Keyboards
     Manufacturer                    Type                    Layout

     Cherry                          MF II                   US
     Cherry/Tandon                   MF II                   German
     Hewlett-Packard                 MF II                   US
     Hewlett-Packard                 MF II                   German
     Tatung                          AT                      German

     There is absolutely NO support for the ancient PC-keyboards (they had 83

     There is only limited support for AT-keyboards [they have 84 keys, and a
     separate numeric keypad, they don't have F11/F12 keys] because the emula-
     tor needs F9 through F12 for control functions, and due to the current
     design of the keyboard driver there is no (full) support for national
     keyboards because of the lack of an ALtGr key.

     MF-keyboards are fully supported, 101- and 102-key versions.

FreeBSD                         January 9, 2000                        FreeBSD


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