sm.4

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 4 代码 · 共 84 行

.\" SCCSID: @(#)sm.4	8.2	3/28/91
.TH sm 4 VAX
.SH Name
sm \- Small VAX monochrome video subsystem
.SH Syntax
.B "device sm0 at uba0 csr 0x200f0000 flags 0x0f  vector smvint"
.SH Description
.NXS "sm interface" "monochrome video subsystem"
.NXR "monochrome video subsystem"
A Small VAX monochrome 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.
.PP
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 a 120-column
by 80-row page that scrolls from the bottom.
This device is capable of being configured as the system console.
.PP
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.
.PP
The third minor device provides an access path for console output
that does not disturb the graphics display.
The caller can open the device 
.PN /dev/smscreen .
When this device is open, the Small VAX monochrome driver
redirects console device output to the input buffer of this device.
This mechanism disables
console output on the Small VAX monochrome screen and saves
the output for 
later display. This preserves the graphic display integrity.
.PP
Input and output on the first and third minor devices are processed by
the standard line disciplines.
.PP
If there is not a special cable (BCC08) on serial port 
3 (printer port), and
the optional video board is not present
(or failed the self-test), the system
will then use the monochrome video as the system console.
All input/output destined for 
.PN /dev/console
will use the monochrome 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,
.PN tip/uucp 
(hardwire, modem, or autodialer)
connection, or user dial-up access.
For further information, see 
.MS ss 4 .
.sp
The Hold Screen key is supported.
The Small VAX monochrome 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).
.sp
.in \-5
.PP
.SH Files
.PN /dev/console
.br
.PN /dev/mouse
.br
.PN /dev/smscreen
.SH See Also
ss(4), ttys(5), MAKEDEV(8)