What does that button do

You know the adage that documentation is to let other people understand how and why you did something, including the other person that is you three months from now?

If I had either documented the steps I took to get one of my long-running projects to an almost-working state, or just written “DO NOT TURN THIS OFF!” on a post-it by the power supply, I wouldn’t have learned an important lesson today.

So I’ve been working on a widget that includes a projector, and the projector I got uses a VGA connector, and running the late-middle-aged linux box in the basement two-headed with analog video would have required another video card and all the interesting configuration that goes with it.

Instead, I thought “Hey! I’ve got got a Via mini-itx board from that digital picture frame project 12 years ago [it’s so old I can’t even find a link to the specs or a review] and it ran debian back then; why don’t I use that and just connect to it remotely?” So a few months back, I hooked it up, attached a new power supply, patched in a CD drive so I could reinstall the operating system to a capacious 30-gig hard disk, and set up XVNC (which took some doing, because parts of the network in the basement really want to think they’re running on IPv6 and way too much of the software involved insists that only IPv4 addresses will do, and the Via makes a Raspberry Pi look like a speed demon).

So once I’d done that, I could run the projector from the Via hardware, but have keystrokes and mouse movements on my main machine control what was being displayed. And I left the Via powered up (it draws a whole 15 watts or so) rather than take the time to debug the startup scripts what would let me just boot it up into a remotely-controllable state that other computers on the network could find.

I left it powered up for months while I did holiday stuff and worked on other projects and other parts of this project, and then, a few days ago I was seized by an urge to save electricity. So this morning and early afternoon I got to go through the whole process of disconnecting the projector, connecting a spare monitor, rebooting the Via (there are a couple of jumper wires plugged into a header for just that purpose, since it won’t just turn on when power is applied), finding out its new IP address, logging into it remotely…

At one point I even had a remote session from Sampo, my main machine, that was open to a desktop on Frame (the Via) where I had opened a remote desktop back to Sampo. It wasn’t quite as slow as you would think. OK, maybe it was.

So next time I do a project like this, I think I’m going to just get a whole new main computer that can do the two-display thing without all the headaches. But if I do that, I won’t be able to take it anywhere. Maybe a Pi and start retiring all the display devices that don’t do HDMI. Hmm, what was that lesson I learned?

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