Wednesday, February 12, 2014

Anatomy of a Cheap USB to Ethernet Adapter

Angus Gratton:

One of them is sold on ebay for $3.85 AU ($3.99 US), including postage to Australia. The other is sold at Apple Stores for $29.


The Apple adapter also has many more small components – two inductors (the cheap adapter has none), over twenty five capacitors (the cheap adapter has only nineteen), more resistors. For the cheap adapter design, every fraction of a cent saved is important!

One thing that surprised me is that the cheap adapter has a functioning blue activity LED, that glows through the enclosure. The Apple adapter actually has a space on the PCB for this, but no LED in place (Apple’s designers presumably nixed it for aesthetic reasons.) I’m surprised the manufacturer paid the few cents to add this feature.

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My guess is that LED indicators are inherited from the dark ages when you'd need to check the light on the floppy disk reader on DOS machines. It looks like Windows users still mostly yank out their USB drives from the machine when the light stops blinking. Without the light, they'd yank it too early or think the drive is busted. -- explanation inspired by a recent ATP episode

@Charles: Windows users are doing it right, in UI/UX/HCI terms. It's the OS's job to protect data integrity at all times, via replication, transaction logs, notification of incomplete transmission, etc. A system that can't even protect itself and its user's data against deliberate disconnection isn't going to fare any better on accidental disconnection, connection failures, Acts of Gods, etc.

Requiring users manually issue an unmount+eject command was the logical approach in the days of 3.5" Superdrives (which didn't have a physical eject button), but OSX software usability has failed to keep up with hardware evolution nor requirements and expectations of modern users. It's the machine's job to make its users' lives easy, not (as computer nerds might believe) the other way around.

Besides, who doesn't love the ol' das blinkenlights? ;)

@has Good point. Now that I think of it, even I find it hard to know for sure when the little drive icon is gone, and I can remove the USB key. I think the OS could do a better job at making it clear (it sure knows to yell at you when you do it wrong!). A hardware light is actually the most direct feedback. It would work even better next to the port itself, on the computer, rather than on the USB device (not sure if that's technically feasible).

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