cfb(4) Kernel Interfaces Manual cfb(4)
Name
cfb - color bitmap graphics
Syntax
device cfb0 at ibus? vector cfbvint
Description
The video subsystem provides a half page or full page, user-accessible bitmap display for graphics. The subsystem consists of 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 action 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 has been entered. 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 cfb(4)
