My desktop setup is two ancient Planar 1910M monitors
turned sideways (1280Y 1024X). They are driven by an
ancient dual-DVI Nvidia GTX 750 Ti (GM107) with the
nouveau driver. They are merged with this startup script:
---------
#!/bin/bash
xrandr --output DVI-I-1 --rotate left --pos 0x0 \
--output DVI-D-1 --rotate right --right-of DVI-I-1
---------
The computer driving them is CentOS 7.3 (actually, the
Scientific Linux "SL" clone). After IBM bought RedHat
and CentOS, long term support is evaporating.
So, time to move to a Debian distro - I chose Mate-Ubuntu
("MU"), which is vaguely like SL and Gnome 2. I will
attempt to configure the desktop and the apps like the
CentOS machine. I can have SL on one screen, MU on the
other.
I have a second tower machine with a dual-DVI Nvidia card,
but only one Belkin two port DVI switch. Before, today I
could only switch the left screen to the new Mate-Ubuntu
machine for A/B comparisons.
My first attempt at switching each screen (independently)
was purchasing an identical used Belkin switch from an
eBay seller. He assured me it was tested and working.
So, I attached it to the left screen with the same cables
and power supply as my first Belkin.
Somehow, it destroyed the DVI input to the attached screen.
Curious, I opened up the second Belkin; one of the flat
cables between boards wasn't even connected. Tested?
BULLSHIT.
Fortunately, I have inexpensive used spare screens, and
the "display glass" of the borked screen can repair the
others when they eventually grow dim or depixelated.
After my revenge fantasies subsided, I rethought my
arrangement. I want only one mouse and keyboard; full KVM
capability is overkill. All I really need to do is switch
between two DVI sources to the right monitor, using the
left screen to switcj keyboard and mouse.
I can also use different xrandr scripts to swap screen
images between left and right screens.
-----
I found a simple "BolAAzul" (?!) digital-DVI-only switch,
$20.25 on Amazon: https://www.amazon.com/dp/B0939XKS86
It arrived two hours ago, and is connected and deployed.
Two DVI cables from the two computers connect to the sides
of the 6 cm square switch box, and a third connector on
the front of the box connects to a third DVI cable to
the right monitor. The switch box came with an external
pushbutton selector switch dongle on a USB-C-connected
cable, which I can use to switch the right screen.
Poorly assembled, mechanically; the physical switch was
loose inside the dongle, and moved about when I pushed
the button. So ...
I wedged the switch into place by forcing a carved 2 mm
dowel into a hole on the opposite side of the switch case
from the USB cable. (dowel == wooden shaft of cotton swab).
Cheesy, but good enough for a hardware hacker.
If the DVI switch still works in a week, I will write an
informative and tepid review for Amazon.
Hardware tamed! Back to Ubuntu distro software, misleading
700 page Linux books, just plain evil advice from random
idiots on the web, and the superb and generous guidance
from the wizards of PLUG.
Keith
--
Keith Lofstrom [email protected]
