[OT] USB KVM switches

From: chris <cb_at_mythtech.net>
Date: Wed Feb 2 21:28:17 2005

>No. You can't connect two A receptacles together with an adapter, nor two
>B receptacles, because USB is asymmetric. Hosts (and downstream hub ports)
>have A receptacles, and devices (and upstream hub ports) have B receptacles.
>Unless the device (or hub upstream port) has a captive cable, in which
>case it has an A plug, which of course can be mated with a A receptacle.

What I meant was, regardless of the connector on the device, and
regardless of the connector on the computer (or host, or whatever is
designed to accept the device), you can still connect them together with
nothing more then a cable with the correct ends (or cable with adaptors).

ie: I have a camera with a mini A socket (I assume A since it is
rectangle and not square), if I loose the cable, and know nothing about
the camera "specs", all I need is a cable that ends in a mini A on one
end, and a regular A on the other. I don't need to know anything else, I
don't need to have any special pinouts, nothing. I can grab any old USB
cable, and slap an adaptor on it if I so wished, and it works.

You simply can't do that with serial. Too many variables. You need to
know more about the connection to do that with serial, and simple generic
adaptors will not always make a 25 pin into a 9 pin (or vice versa).

I do understand that you can't just grab a cable and go computer to
computer or PDA to PDA and expect it to work. I was only referring to
devices that were intended to connect to each other (which is something
you COULD do with serial).

Oh, and you CAN go A to A... like I said in a previous email, I have an
early digital camera that has an A socket on it... socket matches the one
on my computer exactly. The camera isn't a host, it is a device. But I
know that isn't what you were referring to in your reply. Of course, it
only helps illustrate some of your direct frustration with USB... there
is a clear spec, and it STILL isn't followed properly :-)

Received on Wed Feb 02 2005 - 21:28:17 GMT

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