Be it resolved...

I moved my server downstairs and haven't actually fired up X-Windows for a long time, so when I was getting it re-running with the fresh(-ish) new operating system (Slackware 14.2+updates) I am working through getting it running bit by bit (yesterday was the switchover day and it "only" took me about 6 hours... I'd done weeks of part time preparation to make sure it went relatively okay). The only major thing left to do today is the CUPS (printer) configuration and a few little tweaks that I'm finding (luckily I have all my previous config files that took me a lot longer to figure out than it's taking me this time, luckily). I even managed to migrate my database from MariaDB 5 to MariaDB 10 without losing any data (yes, I made a backup first, no worries).

So one funny little thing I did was to update my "xorg.conf" file to support a new monitor (new to the server, not new to me). When I moved it downstairs, I left the eMachines "E19T6W" monitor with my upstairs system (I was using a KVM to switch between it and the server, almost never using the server's direct display), and randomly hooked up an Acer "AL1912s" monitor to it. When I started it with the previous config (I'd forgotten it was a different monitor), it looked ... pretty bad. The light bulb went on and I realized I needed some new monitor specifications. Firstly, Acer doesn't have their monitor manual online anymore from the looks of it, but there were third party sites that had archived it and could be found with a bit of searching. The manual actually gave more data than usual (usually it's just resolution and vertical frequency), so it was a bit of a puzzle for a few minutes to figure out how to adapt the information for a ModeLine in the "xorg.conf" file. The technique I used for figuring out the original file with the previous monitor is in this post: A problem with a happy resolution.

The manual had the following information:

Timing: 1280x1024VESA-1024-75Hz
Display Area: 376.32mm x 301.056mm
Horizontal: 80kHz, positive sync, total dots = 1688, active dots = 1280, clock = 135MHz
    sync width (dots) = 144, front porch (dots) = 16, back porch (dots) = 248
Vertical: 75Hz, positive sync, total lines = 1066, active lines = 1028,
    sync width (lines) = 3, front porch (lines) = 1, back porch (lines) = 38

The ModeLine in the configuration file has the following fields:

PixelClock HDisplay HSyncStart HSyncEnd HTotal VDisplay VSyncStart VSyncEnd VTotal

And that's about as much information I had. Pixel clock was easy. HDisplay had to be the active pixels, so 1280. Sync width is presumably the difference between the HsyncStart and HSyncEnd values, so I guessed that the HSyncStart was the active pixels plus the back porch: 1280 + 248 = 1528. Then the HSyncEnd would be HSyncStart plus the sync width: 1528 + 144 = 1672. Then HTotal would be HSyncEnd plus the front porch: 1672 + 16 = 1688, which (yay) is the total. Doing the same with the vertical lines: VDisplay = 1024, VSyncStart = 1024 + 38 = 1062, VSyncEnd = 1062 + 3 = 1065, VTotal = 1065 + 1 = 1066, again the total number of lines. For the sync polarizations, both are positive. The sync ranges needed to be increased from what they were before, so the final monitor specification ended up as:

Section "Monitor"
    Identifier      "AL1912"
    HorizSync       30.0-85.0
    VertRefresh     50.0-75.1
    DisplaySize     376.32 301.056
    Modeline        "1280x1024" 135.0  1280 1528 1672 1688  1024 1062 1065 1066 +HSync +Vsync
EndSection

And the Monitor line in the Screen section needed to be changed to "AL1912". Worked like a charm!

A fun (new to me) video I found the other day:

"Jain - Makeba (Official Video)" (Watch on YouTube)