Interesting observation with my Unicomp

[macguy80]

I have a Unicomp Spacesaver M. I have it plugged into a 7-port USB hub, upon which each port has its own individual power switch. At certain points in the startup process, and if I switch the port on and off, the status lights on the keyboard flash once in unison, as I would expect.

However, my mouse is plugged into an adjacent port, and one day, I was having trouble with it, so I switched the port off and on. When I switched the mouse's port on, the status lights on the keyboard flashed once. I flipped it again, and it did the same.

None of my other keyboards do this in response to the mouse's port being switched. My best guess is that the shielding on the cable is substandard or otherwise degraded.

Has anyone else seen this kind of thing? (Not that a switched USB port is all that commonly encountered.)

[njbair]

It's the hub externally powered? My guess is, the slight surge in current going to the mouse, causes a momentary "brownout" until your computer can regulate the current for the new demand. So what you're actually seeing is your Unicomp losing power for a second and then coming back on.

[macguy80]

Yes, it is externally powered. What makes me wonder is that this phenomenon does not happen with any other keyboard -- just the Unicomp.

[rowdy]

Model M and probably Unicomp BS keyboards tend to suck down a fair bit of power, right?  So fluctuations in power availability might cause a sufficient drop in current to cause the keyboard to reset.