One Reply to “Various links”

1. Hmm. I’ve been meaning to post this whatever-it-is for a while, so I might as well do it before things scroll off the page. USB is largely a success story (surprised me), USB is pretty cool, there are probably lessons to be taken from the “completionism” of USB…

   …but do anything approximately right, and someone will still find a way to screw it up. In this case, the award goes to the engineers behind the HP PSC2210, in combination with that first wave of board designers who decided USB should carry power, but that the host(s) shouldn’t be responsible for providing it.

   So this particular printer/scanner/fax combo, a fairly expensive device at the time, not portable by any stretch of the imagination, and imbued with its own hefty power supply (indeed, it *requires* its own supply, since it’s intended to run as a standalone appliance as much as a peripheral)… requires the ‘full’ DC power to be present on the cable for its USB B connection to work. Helpfully, it will “usually” work on a less-than-full-current link, but not reliably; I shudder to think what’s going on in that design.

   Anyone else feel like they don’t have enough data to be able to ‘reward’ manufacturers who fully obey/correctly implement specs?

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