Wang 300 Calc

Tony Duell ard at p850ug1.demon.co.uk
Fri Sep 14 15:09:17 CDT 2007


> 
> On 13/09/2007, Gordon JC Pearce <gordonjcp at gjcp.net> wrote:
> 
> > It still doesn't excuse having a physically-but-not-functionally
> > interchangeable connector for PS/2 mice and keyboards, though.  That is
> > where USB has a big win.
> 
> Absolutely 100% concur. That was criminally stupid.

IIRC, the PS/2 mouse interface and PS/2 keyboard interface are very 
similar. Both are TTL level interfaces with clock and data lines, both 
have 4 signals on the connector (+5V, ground, clock, data), and the data 
transfer protocol is much the same.

IIRC, the pin assignemts of the 2 interfaces is the same too, and it's
possible to make a device where you can plug the mouse and keyboard into
either connector, and detect what sort of device is plugged into a given
socket. The fact that most PCs didn't let you do that is not the fault of
the interface. 

So why not use the same connector for the 2 interfaces?

-tony



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