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Hi-Res X-Windows
Ok, so here I am nice an happy with my system displaying
X-Windows at 1280x1024x32bpp. then it occures to me; my
video card can handle 1600x1200x32bpp and so can my monitor.
So, why am I sitting here in this lower resolution? Well,
the only reason I could think of was that XF86Setup would
only let me choose from monitors that could only go up to
1280x1024, and I couldn't put my own parameters into the
config tool to setup my monitor.
So, what am I supposed to do? Well, being the 'brave soul'
that I am, I decide to start looking around in my /etc/XF86Config
file. From looking in there I couldn't find enough
info to do what I wanted, but I did find a reference to
a "VideoModes How-To" that gets distributed with X-Win.
Ok, enough is enough, it is time for to get down to the
nitty gritty on what I did. Oh, yeah we'll need a calculator
handy too.
1) I got out my owners manuals for both my vid card and
my monitor (these are a must because there is some information
that you'll need from there)
2) I looked up in both of my manuals to make sure that
both devices will perform as desired. This step is important
you must note the max scan rates of your monitor and the
scan rates that your video card uses for the various resolutions.
If they both "jive" (i.e. the video card uses horizontal
and vertical scan rates lower than you monitors max hor.
and vert. scan rates) with each other, then we're in business
and ready to continue.
3) XF86Config wants a number of parameters in under the
Section "Monitor" area in order to display X on your monitor.
The area under Section "Monitor" that we are concerned with
at the moment are the lines that start with Modeline. On
the lines that are already there you will see a bunch of
numbers. I'll get to what they are a little later.
4) Get out a blank sheet of paper and make up a table that
is made up of 2 rows of 10 cells.
Like this:
+------+------+------+------+------+------+------+------+------+------+
|.Res..|..dot.|..hor.|..sys.|..sye.|.hore.|.vert.|..sys.|..sye.|.verte|
+------+------+------+------+------+------+------+------+------+------+
|......|......|......|......|......|......|......|......|......|......|
+------+------+------+------+------+------+------+------+------+------+
in the cell under "res" put the
desired resolution that you want to run. under "dot"
put your monitor's "Video bandwidth"
(in my case it's 135(the units don't matter we just want the
number)), under "hor" put the horizontal size of the desired
resolution, leave "sys", "sye" and "hore" blank for now. under
"vert" place the vertical resolution you want in there and
leave the rest of the cells empty for now.
with that done we should have something like: res........dot..hor...sys...sye...hore...vert..sys..sye..verte
1600x1200..135..1600.....................1200.................
5) get out that calculator. we are going to calculate
"hore" now. to do that you take "hor"
(1600) and divide it by .8 (1600/.8). for this example
that gives us 2000. Your number maybe different if you are
using a different resolution. if that number that we just
calculated is evenly dividable by 8 (i.e. if you divide
2000 by 8 and have no remainders) go ahead and put it in
the slot under "hore". If your number is not evenly divisible
by 8 then round it down to the nearest number that is. (i.e.
if you number is 1887 you would round it to 1880) once you
have it rounded to a nice number that 8 can go evenly into
then go ahead and put your number into the "hore" slot.
6) Now for "verte". to calculate "verte" you take the
number in "vert"(1200) and multiply it by 1.05 (1200 x 1.05).
If that answer is a multiple of 8 then stick it in "verte".
If not, then we'll have to round it down.
1200x1.05=1260
1260/8=157 r 4 **not a multiple of 8 so now we round it down
1256/8=157 **no remainder so we're can stick 1256 into "verte"
now we should have:
res........dot..hor...sys..sye..hore..vert..sys..sye..verte
1600x1200..135..1600............2000..1200............1256
7)Now to fill in the rest of the data. for the 2 cells
between "hor" and "hore" we just do some simple addition:
sys=hor+32
sys=1600+32=1632 **so we put 1632 into the "sys" cell next
to "hor"
sye=hore-32
sye=2000-32=1968 **so we put 1968 into the "sye" cell next
to "hore"
8) For the parameters between "vert" and "verte" it's
a even easier:
sys=vert+3
sys=1200+3=1203 **so we put 1203 into the "sys" cell next
to "Vert"
sye=sys+3
sye=1203+3=1206 **so we put 1206 into the "sye" cell next
to "verte"
9) so now our table should look something like this:
res........dot..hor...sys...sye...hore..vert..sys...sye...verte
1600x1200..135..1600..1632..1968..2000..1200..1203..1206..1256
10)to add this info to your XF86Config file you just have
to go to the section labeled Section "Monitor", and create
a new line under a current Modeline line and enter your
data. It should look something like this now:
Section "Monitor"
Identifier "Primary Monitor"
VendorName "CTX"
ModelName "1785XA"
HorizSync 31.5-84.3
VertRefresh 50-120
Modeline "1280x1024" 110.00 1280 1328 1512 1712 1024 1025
1028 1054
Modeline "1600x1200" 135.00 1600 1648 1984 2000 1200 1201
1204 1256
EndSection
The line that we added is in bold.
11) Now we need to add the new resolution to the Section
"Screen" After you do that it should look like:
Section "Screen"
.
.
.
SubSection "Display"
Depth 32
Modes "1600x1200" "1280x1024"
EndSubSection
EndSection
12) Fine tuning, if you find that the display is flickering
too much you can go in and increase the value that we put
under "dot" (135) by increments of
5 or 4 (mine started at 135 but i had to increase
it up to 156 to get a nice flicker-free display).
Further adjustments, such as centering, can be done with
the controls on your monitor or by using the app "xvidtune"
if your distribution comes with it.
It took me a couple of hours to get this right, but I was
working from a HowTo that I had to sort out all of the important
data from. Hopefully it won't take you guys as long.
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