On Sun, Jun 22, 2003 at 10:39:14PM -0700, David Harris wrote: > Hi all- > I have noticed that mice these days come with a USB connector. They also > come with an adaptor that let's you plug them into a PS2 mouse port. What > exactly does this adaptor do? Is it a trivial item, with the smarts in > the mouse/PC or does it convert from PS2<-->USB? The adapter is trivial (+5v/gnd straight through, and +D/-D to data, clock I imagine) but the mouse is smart enough to tell what it's plugged into and send the appropriate output. Both protocols are host-initiated (in theory PS/2 starts "on", but by default all of the reporting flags are off). The state machine is probably something like "if [line that PS/2 clk is on] goes low for [a long time, I forget exactly, but an eternity by USB standards] then this is PS/2 and I should start driving CLK and reading data when it's released". -- Ben Jackson http://www.ben.com/ -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.