pm(4)							     Kernel Interfaces Manual							     pm(4)

Name
       pm - monochrome/color bitmap graphics

Syntax
       device	 pm0  at ibus?	vector pmvint

Description
       The video subsystem provides a half page or full page, user-accessible bitmap display for graphics.  The subsystem consists of a 256 Kbytes
       (monochrome) or a 1 Mbyte (color) block of dual port RAM, a mouse or tablet, a keyboard, and a video monitor.

       The subsystem device driver supports a hybrid terminal with three minor devices.  The first minor device emulates a glass tty with a screen
       that  appears  as  an 80-column by 56-row page that scrolls from the bottom.  This device is capable of being configured as the system con-
       sole.

       The second minor device is reserved for the mouse.  This device is a source of mouse state changes.  (A state change is defined as  an  X/Y
       axis mouse movement or button change.)  When opened, the driver couples movements of the mouse with the cursor.	Mouse position changes are
       filtered and translated into cursor position changes in an exponential manner.  Rapid movements result in large	cursor	position  changes.
       All cursor positions are range checked to ensure that the cursor remains on the display.

       The  third  minor  device  provides  an access path for console output that does not disturb the graphics display.  The caller can open the
       device When this device is open, the graphics driver redirects console device output to the input buffer of this  device.   This  mechanism
       disables console output on the screen and saves the output for later display. This preserves the graphic display integrity.

       Input and output on the first and third minor devices are processed by the standard line disciplines.

       The Hold Screen key is supported. The graphics driver treats this key as if CTRL/S or CTRL/Q had been pressed. Pressing the Hold Screen key
       suspends the output (if it is not already suspended). To resume the output, press the Hold Screen key again.

Files
       Console terminal or graphics device

       Mouse or tablet graphics device

       Console message window for workstation

See Also
       console(4), devio(4), tty(4), ttys(5), MAKEDEV(8)

								       RISC								     pm(4)