sg(4) — VAX
Name
sg − Small VAX color video subsystem
Syntax
device sg0 at uba0 csr 0x3c000000 flags 0x0f vector sgaint sgfint
Description
A small VAX color video subsystem provides a half-page or full-page, user-accessible bitmap display for graphics applications. The device consists of a 128-Kbyte block of dual port RAM, a VSXXX-AA mouse or VSXXX-AB tablet, and a 19-inch video monitor.
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 number 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 is opened in the raw mode by default. Opening the third device makes the driver function like a pseudo-tty in that the output destined for the first minor device is channeled to the third instead.
If there is not a special cable (BCC08) on serial port 3 (printer port), the system will then use the color video as the system console. All input/output destined for /dev/console will use the color video instead. (This is done by overwriting the device switch tables.) There is a second set of device switch entries configured that may be used as an additional terminal, tip/uucp (hardwire, modem, or autodialer) connection, or user dial-up access. For further information, see ss(.).
The Hold Screen key is supported. The Small VAX color driver treats this key as if CTRL/S or CTRL/Q is typed. Pressing the Hold Screen key suspends the output if it is not already suspended. The output will be resumed by pressing this key again (if the output was suspended).
Files
/dev/console
/dev/sg0
/dev/sgscreen