qv(4)
NAME
qv − VCB01 (QVSS) video subsystem
SYNTAX
device qv0 at uba0 csr 0177200 flags 0x0f vector qvkint qvvint
DESCRIPTION
A VCB01 provides a half-page or full-page, user-accessible bitmap display for graphics applications. The device consists of a 256 kbyte Q22 bus memory array, a 15-inch or 19-inch video monitor, and a VX10X-EA mouse.
The subsystem device driver supports a hybrid terminal with three minor devices. The first device emulates a glass tty with a screen that appears as a 120-column by 80-row page that scrolls from the bottom. This device is capable of being configured as the system console.
The second minor device is opened in the raw mode by default. Opening the second device makes the driver function like a pseudo-tty in that the output destined for the first minor device is channeled to the second instead. Input and output on the first two minor device numbers are processed by the standard line disciplines.
The third minor device number is reserved for the mouse. This device is a source of mouse state changes. (A state change 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.
If there is a VCB01 module at the standard address, the system will use it as the system console. All input/output destined for /dev/console will use the VCB01 instead. (This is done by overwriting the device switch tables.) There is a second set of device switch entries configured for the console that may be used as an additional terminal or printer port by making a special device file using major number 38 and minor number 0 and making the appropriate entry in /etc/ttys.
RESTRICTIONS
The use of the bitmap as source or destination of I/O operations is not supported. Minor devices 1 and 2 are read only and are the only ones supported by the MAKEDEV script. Shared access by multiple processes is not constrained or supported. The system only supports one VCB01. The mouse device buffers the last 50 events (state changes). If the console port has been enabled as an additional terminal it must be disabled before removing the VCB01 to avoid two login processes on the same device.
FILES
/dev/qvscreen
/dev/mouse