Sometimes it’s the hardware

A few years ago, I bought this cute little USB hub from Fry’s. It was one of those faux-Apple style pieces of hardware, with that milky-glass look, ultra-small and stylish. I used it to connect my keyboard, mouse, and printer to the laptop, but the printer only worked when it was connected directly instead of through the hub. I cursed Linux. Then I started working on the Macbook Air with the same setup. and when the printer didn’t work with Mac OS X, I cursed printer firmware writers. Then my keyboard kept inserting random characters, kind of like there was an echo delay. It didn’t do that when connected directly, only through the hub. Hey… wait a minute… I switched to the new even cooler USB hub I bought on a whim last time I was at Fry’s, and voila, printer and keyboard work perfectly. It never even occurred to me that it could be hardware.

Oh yeah, the Macbook Air. I love it.

5 thoughts on “Sometimes it’s the hardware”

  1. transaction translator

    Probably a single-TT versus multi-TT problem. You would think that a USB 2.0 480MB hub could handle eight keyboards, right? Not if it is single-TT. I don’t know why they build single-TT hubs. Of course single or multi isn’t printed on the box either.

  2. about that printer firmware

    Speaking (typing?) as a printer firmware writer …

    The printer has no idea whether the upstream USB connection is a hub or a PC and no ability to misbehave for only a hub. When the master sends packets down the bus to the printer’s address, the printer sends packets back.

    My first guess here would have been that the hub handles only low-speed transactions (good enough for keyboard and mouse) but not full-speed (required for just about everything else.) I’ve never heard of such a hub, and this wouldn’t account for the random characters.

    You can find the most exquisite junk at Fry’s.

    Andrew Klossner, andrew@cesa.opbu.xerox.com

  3. Ha! As someone who works on USB, I *always* blame the hardware first. Jamey did comment that repeating characters from a USB keyboard might actually be the X server’s fault, but random characters sounds like a USB problem. Got a USB VID/PID for the device so I can avoid it?

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