.\" $XConsortium: Xdec.man,v 1.6 94/04/17 20:29:52 gildea Exp $
.\" Copyright 1991 Digital Equipment Corporation
.\" Copyright (c) 1993  X Consortium
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.TH XDEC 1 "Release 6" "X Version 11"
.SH Name
Xdec \- X server for Digital RISC machines
.SH Syntax
.B Xdec
[
.I options
]
.SH Description
.NXR "Xdec command to start X server"
.NXR "X server"
.NXR "X Window System"
.NXR "X Window System" "starting the server"
.NXR "Starting the server in the X Window System"
.NXM "Starting the server in the X Window System"
.PP
The
.PN Xdec
command starts the X server.  The
.PN Xdec
command supports the following hardware configurations:
.nf

   DECstation 2100 Monochrome or Color Workstations
   DECstation 3100 Monochrome or Color Workstations
   DECstation 5000/100/200 CX or MX Single or Multiscreen Workstations
.fi
.PP
This server should run on reasonable one
bit or eight bit Ultrix/RISC TURBOchannel displays of any resolution, if
correct device driver support is present.
The server queries the device driver interface to determine if a
suitable display device is installed, and if so, configures the server
appropriately.
.LP
The command that executes the server is specified together with its
command line options in the
.PN /etc/ttys
file or using xdm(1) and, therefore, is automatically run when your system is
started in multiuser mode.
.\"Use the 
.\".PN xset
.\".B \-q
.\"command to query the server for the options that are currently set.
Optionally, you can create an
.PN /etc/screens
file containing device-dependent command line 
options (separated by spaces) and use it to start the server.
Command line options specified in the 
command starting the X server override those specified in the
.PN /etc/screens
file.
.PP
Start the server in bug compatibility mode (with the \fBbc\fP
option) to remain bug-for-bug compatible with previous releases of the server.
.SH Options
In addition to the normal server options described in the \fIXserver(1)\fP
manual page, \fIXdec\fP accepts the following 
device-dependent, vendor-specific options.
When the server is run on multiscreen capable platforms, selected
device-dependent options take an optional screen-specification argument.
Omitting the screen-specification argument defines the parameter for all
available screens.
.IP "\fB\-btn\fP \fInum\fP" 20
Specifies the number of buttons on the pointer device.  The default is three
for a mouse device and four for a tablet device.
.IP "\fB\-bp\fP[\fIscreen\fP]  \fIcolor\fP" 20
Sets the color of black pixels for the screen.
The \fIcolor\fP argument can be a named color from the
.PN rgb
database or a number sign (\fC#\fP) followed by a hexidecimal number.
.IP "\fB\-class\fP[\fIscreen\fP]  \fIvisual class\fP" 20
Sets the visual class for the root window of the screen.  Possible values
are
.PN StaticGray ,
.PN StaticColor ,
.PN PseudoColor ,
.PN GrayScale ,
and
.PN TrueColor .
.\" .PN DirectColor .
.IP "\fB\-dpi\fP[\fIscreen\fP]  \fInum\fP" 20
Sets the dots per inch for the x and y coordinates.
.IP "\fB\-dpix\fP[\fIscreen\fP]  \fInum\fP" 20
Sets the dots per inch for the x coordinates.
.IP "\fB\-dpiy\fP[\fIscreen\fP]  \fInum\fP" 20
Sets the dots per inch for the y coordinates.
.LP
By default on multiscreen systems, the server presumes the
left hand most screen is screen zero, screen one to its right, screen
two yet further to its right, and so on.
The cursor will track from the
right hand edge of screen zero to the left hand edge of screen one,
from the right hand edge of screen one to the left hand edge of screen two.
This arrangement can be modified in various ways, to support 
other physical arrangements of monitors.
.IP "\fB\-edge_bottom\fP\fIscr1\fP \fIscr2\fP" 20
Attaches the bottom edge of the screen specified by \fIscr1\fP to the
screen specified by \fIscr2\fP.
.IP "\fB\-edge_left\fP\fIscr1\fP \fIscr2\fP" 20
Attaches the left edge of the screen specified by \fIscr1\fP to the
screen specified by \fIscr2\fP.
.IP "\fB\-edge_right\fP\fIscr1\fP \fIscr2\fP" 20
Attaches the right edge of the screen specified by \fIscr1\fP to the
screen specified by \fIscr2\fP.
.IP "\fB\-edge_top\fP\fIscr1\fP \fIscr2\fP" 20
Attaches the top edge of the screen specified by \fIscr1\fP to the
screen specified by \fIscr2\fP.
.IP "\fB\-wp\fP[\fIscreen\fP]  \fIcolor\fP" 20
Sets the color of white pixels for the screen.  The syntax for \fIcolor\fP
is the same as for the argument to the \fB\-bp\fP option.
.IP "\fB\-tb\fP \fIn\fP" 20
Opens
.PN /dev/tty0\fIn\fP
\fRfor graphics tablet communications.
.IP "\fB\-pcm\fP \fIn\fP" 20
\fROpens
.PN /dev/tty0\fIn\fP
\fRfor Protocol Control Module (PCM) communications.
The two free serial ports on the DECstation correspond to
.PN /dev/tty00
and 
.PN /dev/tty01 .
Dial boxes and button boxes must be connected through these two ports.
.SH Restrictions
If options not listed in this reference page are 
used, the server may fail. Using invalid options for the X server 
in the 
.PN /etc/ttys
file may cause the workstation to behave as if the 
X server is hung.
.PP
Multiscreen configurations can contain either two- or three-color frame
buffer display devices or monochrome frame buffer display devices.
.PP
Color and monochrome frame buffer display devices
can be installed in the same workstation, however applications
built before X11 release 5 may become confused due to poor initial design
of resource files.
.PP
To connect two screens, two command line options must be
issued.  Attaching two screens using only one 
.PN -edge_ 
argument produces a one-way mouse-travel path.
You can create a wrap-around mouse path by attaching 
noncontiguous screen edges.
The 
.PN -edge_ 
arguments are disabled on single screen systems.
.PP
Nonsensical screen connections are not allowed; the top edge of a
particular screen must be connected with the bottom edge of
another screen, and the right edge of a particular screen
must be connected with the left edge of another screen.
Left and right edges cannot be connected to top or bottom
edges.
.SH Examples
The following example specifies that screen 
.PN 0
has a resolution of
100x100 dots
per inch and screen 
.PN 1 
has a resolution of 75x70 dots per inch:
.EX
Xdec -dpi0 100 -dpix1 75 -dpiy1 70
.EE
.PP
If no screen is specified, the value specified is used
for all screens.  If the screen resolution is not specified using
command line options, a default value
based on pixel dimensions and screen size is calculated for
each screen.
.PP
The following example specifies that black pixels on screen
.PN 1
have the hexadecimal value 3a009e005c0 prefixed with a
number sign (\fC#\fP) and white pixels on screen
.PN 1
are color "wheat" from the X rgb color database.
.EX
Xdec -bp1 #3a009e005c0 -wp1 wheat
.EE
For monochrome display devices, values of 0 and 1
are the only valid pixel colors.
.PP
To specify the default visual class
of a root window on a particular screen, append the screen
number (\fC0\fP, \fC1\fP, or \fC2\fP) to the
.PN \-class
command line option.  Possible visual classes are:
StaticGray, StaticColor, PseudoColor, GrayScale, and TrueColor.
The following example specifies that the screen
.PN 0
root window is a TrueColor visual, and the screen
.PN 1
root window is a PseudoColor visual.
.EX
Xdec -class0 TrueColor -class1 PseudoColor
.EE
.PP
The following example attaches screen
.PN 1
above screen
.PN 0
and screen
.PN 2
to the right of screen
.PN 0
(an L-shaped configuration):
.EX
Xdec -edge_top0 1 -edge_bottom1 0 -edge_right0 2 -edge_left2 0
.EE
.PP
The following example is identical to the default state (a
horizontal line) with the addition of a wraparound from
screen
.PN 0
to screen
.PN 2 :
.EX
Xdec -edge_left0 2 -edge_right0 1 -edge_left1 0 -edge_right1 2 \e
-edge_left2 1 -edge_right2 0
.EE
.SH Files
.PN \&~/.Xdefaults
.br
.PN /etc/ttys
.br
.PN /etc/screens 
.SH See Also
X(1X), xdm(1), Xserver(1)
.\"XServer(1X)
.\"bitmap(1X), 
.\"keycomp(1X), 
.\"dxcalc(1X),
.\"dxcalendar(1X),
.\"dxcardfiler(1X)
.\"dxclock(1X), 
.\"dxmail(1X),
.\"dxnotepad(1X), 
.\"dxterm(1X), 
.\"dxwm(1X), 
.\"uwm(1X), 
.\"xedit(1X),
.\"xfd(1X), 
.\"xhost(1X), 
.\"xload(1X), 
.\"xmh(1X),
.\"xset(1X),
.\"xsetroot(1X),
.\"xwininfo(1X)
.br
\fIX Window System: The Complete Reference to Xlib, X Protocol, 
ICCCM, XLFD,\fP by Robert W. Scheifler and James Gettys, 
Second Edition, Digital Press, 1990
.br
"X Window System Toolkit: The Complete Programmer's Guide
and Specification, by Paul J. Asente and Ralph R. Swick,
Digital Press, 1990
.br
\fIOSF/MOTIF Programmer's Guide and OSF/MOTIF Reference
Guide,\fP Open Software Foundation, Prentice-Hall, 1990