When you seriously ask this question, you're propably on the wrong track. I'm not trying to make you go and buy a second monitor, but to tell you how to get it work. Anyhow, here are some reasons I could think of:
It's not very much you need to set up a multi screen system: basically two (or more) monitors and two (or more) graphic cards or alternatively a dual-head graphics card. I didn't do a comparsion of all available cards, but Martox cards work excellent for me, so I can recomend these. At last you need an appropriate OS. I will talk about linux in this document but any OS should do. (And NO!, windows is NOT an OS and will not work (at least not as you intended it to work. It doesn't work without a graphics card, it crashes quite often with one, so why the hell should it work with two?!). Anyhow, for linux you definitely need X11 and possibly a framebuffer for the console. I don't know of any window manager not supporting multiscreening, but you might want to take a look at "4 Choosing the right window manager" to get an idea what you can (and should) expect from the window manager. And last (but not least) you might need a bigger desk.
The software you have to install is
Amazingly short list, eh? Well, but that's all you need. Now all you
need to do is set it up. The configuration file usually resides at
/etc/X11/XF86Config-4, but this may vary on your
system.
XFree86's config file is devided into
"sections". At the time of this writing there are
12 sections, the important ones are:
For a (complete?) list of configuration options read the
XF86Config(5x) manpage, available at xfree86.org.
XF86Config-4 as an
exampleThis is my very own XF86Config-4 which is meant to be a
help for you. If you simply copy this configuration your X is very likely
to misbehave, so edit it first! Anyhow, you can download it here.
# XFree86 4.0 configuration by Florian "octo" Forster (2002-06-03)
# This approach uses xfs which may or may not be installed at your system..
Section "Files"
FontPath "unix/:7100"
EndSection
Section "Module"
Load "dbe" # Double-buffering
Load "GLcore" # OpenGL support
Load "dri" # Direct rendering infrastructure
Load "glx" # OpenGL X protocol interface
Load "extmod" # Misc. required extensions
Load "v4l" # Video4Linux
# Load "pex5" # PHIGS for X 3D environment (obsolete)
# Load "record" # X event recorder
# Load "xie" # X Image Extension (obsolete)
# You only need the following two modules if you do not use xfs.
# Load "freetype" # TrueType font handler
# Load "type1" # Adobe Type 1 font handler
EndSection
Section "InputDevice"
Identifier "Keyboard0"
Driver "keyboard"
Option "XkbLayout" "us"
EndSection
Section "InputDevice"
Identifier "Mouse0"
Driver "mouse"
Option "Device" "/dev/mouse"
Option "Protocol" "IMPS/2"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection
Section "Monitor"
Identifier "LKM0B63"
VendorName "Novita"
ModelName "Unknown"
HorizSync 30 - 69
VertRefresh 47 - 104
Option "dpms"
EndSection
Section "Monitor"
Identifier "Philips"
VendorName "Philips"
ModelName "107E20"
HorizSync 30 - 70
VertRefresh 50 - 160
Option "dpms"
EndSection
Section "Monitor"
Identifier "SSI"
VendorName "Seiko Instruments"
ModelName "CM-1440-20"
HorizSync 31 - 40
VertRefresh 50 - 90
EndSection
Section "Device"
Identifier "Matrox_Mystique"
Driver "mga"
BusID "PCI:0:8:0"
EndSection
Section "Device"
Identifier "Matrox_G550_0"
Driver "mga"
BusID "PCI:1:0:0"
Screen 0
EndSection
Section "Device"
Identifier "Matrox_G550_1"
Driver "mga"
BusID "PCI:1:0:0"
Screen 1
EndSection
Section "Screen"
Identifier "Screen 0"
Device "Matrox_G550_0"
Monitor "Philips"
DefaultDepth 16
Subsection "Display"
Depth 24
Modes "1152x864" "800x600" "640x480"
EndSubSection
Subsection "Display"
Depth 16
Modes "1152x864" "800x600" "640x480"
EndSubSection
EndSection
Section "Screen"
Identifier "Screen 1"
Device "Matrox_G550_1"
Monitor "LKM0B63"
DefaultDepth 24
Subsection "Display"
Depth 24
Modes "1024x768"
EndSubSection
EndSection
Section "Screen"
Identifier "Screen 2"
Device "Matrox_Mystique"
Monitor "SSI"
DefaultDepth 24
Subsection "Display"
Depth 24
Modes "800x600"
EndSubSection
EndSection
Section "DRI"
Mode 0666
EndSection
Section "ServerLayout"
Identifier "octo configured"
Screen "Screen 2"
Screen "Screen 0" LeftOf "Screen 2"
Screen "Screen 1" LeftOf "Screen 0"
InputDevice "Mouse0" "CorePointer"
InputDevice "Keyboard0" "CoreKeyboard"
EndSection
ServerLayout
sectionThe ServerLayout section tells the X server in which
relation to each other the screens are located. Possible keywords for
relationships are "Absolute", "RightOf",
"LeftOf", "Above", "Below" and
"Relative". The very most setups will be okay with using
"LeftOf" (or "RightOf", if you wish) only, but more
complex setups (with probably more than just two screens) may need the
other options..
Choosing a window manager is mostly a question of style and comfort I
guess.. My very favorite window manager is larswm, a very minimalistic one.
Another window manager I like a lot is golem, also kinda minimalistic
but enhanced by a bunch of plugins. A long list of the most common and
some very exotic window managers can be found at xwinman.org, a site offering tonns of
information on X, too. (Almost) All window managers support
multimonitor-usage, since the window manager itself doesn't have to know
very much about this case. In general you can think of one window manager
being started per screen, which isn't exactly what is happening, but
close. If you think of your screens as being run by different instances
of the window manager it's easier to understand why you can't move windows
across the screens, for instance. When seeing this scenario from the
window manager's perspective you see, that each window manager handles
exactly one screen, which is why basically every window manager supports
this mode. However, this would be too easy, so there is an extra mode,
called xinerama (described in detail
in section 5). In this mode you can move windows over screen borders onto
another screen, but there needs to be done some extra work in the window
manager since the screen doesn't neccessarilly need to be rectangular
anymore.. And window manager certainly differ in support for this mode.
golem has such support,
larswm doesn't.. (Actually, I've
written a Xinerama-patch
for larswm, but it's not in the main distribution) So if you want to
use xinerama you should think about this for a second. By the
way: there are window managers which support two or more physical screens
and moving windows between them, but with xinerama being
available I wouldn't build onto such a "homebrew" solution..
xineramaxinerama is an extension to XFree86 (versions 4.0 and
above) which combines the physical screens to one big virtual screen. With
this process being absolutely transparent to the window manager it's a
whole lot easier to realize a reasonable support for multiscreening.
Although you don't have to rewrite your window manager if you want to add
support for xinerama there are still some things you should take care of.
Windows shouldn't pop up between screens, e.g. Windowmanagers doing this
include Window Maker,
golem and
Sawfish, to name just a
few.
If you want to use xinerama you have to start your
X-server in an appropriate way. This may mean that you have to edit your
startx script.. Running your X-server from the console you
can load xinerama like this:
octo@leeloo:~ $ /usr/X11R6/bin/X +xinerama