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WSDISPLAY(4)              NetBSD Programmer's Manual              WSDISPLAY(4)


NAME

     wsdisplay - generic display device support in wscons



SYNOPSIS

     wsdisplay* at vga? console ?
     (VGA display on ISA or PCI)
     wsdisplay* at pcdisplay? console ?
     (generic PC (ISA) display)
     wsdisplay* at tga? console ?
     (DEC TGA display, alpha only)
     wsdisplay* at pfb? console ?
     (PCI framebuffer, bebox only)
     wsdisplay0 at ofb? console ?
     (Open Firmware framebuffer, macppc only)
     wsdisplay* at nextdisplay? console ?
     (NeXT display)
     wsdisplay0 at smg0
     (VAXstation small monochrome display)
     options WSDISPLAY_DEFAULTSCREENS=N



DESCRIPTION

     The wsdisplay driver is an abstraction layer for display devices within
     the wscons(4) framework. It attaches to the hardware specific display de-
     vice driver and and makes it available as text terminal or graphics in-
     terface.

     A display device can have the ability to display characters on it (with-
     out help of an X server), either directly by hardware or through software
     putting pixel data into the display memory.  Such displays are called
     ``emulating'', the wsdisplay driver will connect a terminal emulation
     module and provide a tty-like software interface. In contrary, non-emu-
     lating displays can only be used by special programs like X servers.

     The console locator in the configuration line refers to the device's use
     as output part of the operating system console. A device specification
     containing a positive value here will only match if the device is in use
     as system console. (The console device selection in early system startup
     is not influenced.) This way, the console device can be connected to a
     known wsdisplay device instance. (Naturally, only ``emulating'' display
     devices are usable as console.)

     The logical unit of an independant contents displayed on a display (some-
     times referred to as ``virtual terminal'' ) is called a ``screen'' here.
     If the underlying device driver supports it, multiple screens can be used
     on one display. (As of this writing, only the vga(4) and the VAX ``smg''
     display drivers provide this ability.)  Screens have different minor de-
     vice numbers and separate tty instances.  One screen posesses the
     ``focus'', this means it is displayed on the display and its tty device
     will get the keyboard input. (In some cases - if no screen is set up or
     if a screen was just deleted - it is possible that no focus is present at
     all.)  The focus can be switched by either special keyboard input (typi-
     cally CTL-ALT-Fn) or an ioctl command issued by a user program.  Screens
     are set up or deleted through the /dev/ttyEcfg control decice (pre-
     ferrably using the wsconscfg(8) utility). Alternatively, the compile-time
     option
     WSDISPLAY_DEFAULTSCREENS=N will set up N screens of the display driver's
     default type and using the system's default terminal emulator at autocon-
     figuration time.



FILES

     /dev/ttyE* Terminal devices (per screen).

     /dev/ttyEcfg Control device.

     /usr/include/dev/wscons/wsconsio.h



BUGS

     The wsdisplay code currently limits the number of screens on one display
     to 8.

     The terms ``wscons'' and ``wsdisplay'' are not cleanly distinguished in
     the code and in manual pages.

     ``non-emulating'' display devices are not tested.



SEE ALSO

     wscons(4), wsconscfg(8), wsconsctl(8), wsloadfont(8), vga(4),
     pcdisplay(4), tty(4)

NetBSD 1.4                      March 20, 1999                               2