The
Macintosh computer (and the legacy-free
iMac) paved the way for the
USB devices of
today. However, one of the little
ironies is that the
Macintosh keyboard was not fully USB compliant until around the middle of 2000.
If you plug in a
Macintosh keyboard to a
Windows machine, you will
blue screen the
computer, if you press the
power button. This is because the
USB implementation on a
Macintosh involves dropping the fourth pin low to turn on the
machine. This
signal, which is out of spec for
USB, is not handled by many
drivers, including that of
Windows 2000 RTM. The low fourth pin tells the
Macintosh to come out of sleep mode, or to turn on or off.
I learned this because the keyboard
drivers that I worked on were for a fully USB
compliant board, as are the million other USB keyboards out there. In the old
ADB system, Apple had two pins for this purpose, one for turning on the computer, and one for turning off the computer. We discovered this because someone's Mac turned off, but never back on again with the button on that keyboard (but it worked with other boards; We finally took it apark with a multitester to find out why.)
They controlled the
technology, and thus did not have any problems getting it to work with what their users expect. Apple's innovation, which they did not adhere to. Finally, the
USB committee got the them to fix up their keyboards, and now they do something in software for that
key, or so I am told.