Re: PS-2 Keyboard for Aplle II ?

["thewises" <thewises@enter.net>]

"Knut Roll-Lund" <kr-lund@nogarbage.online.no> wrote in message 
V5CdnQVs9vZEEive4p2dnA@telenor.com">news:V5CdnQVs9vZEEive4p2dnA@telenor.com...
> Knut Roll-Lund wrote:
> ...
>> to be fullfilled. The keyboard side is no problem, there are numerous 
>> examples of how to bit bang the PS/2 master.
> ...
>
> Just reread my own post... correction there: the keyboard interface is not 
> PS/2 it is AT, and the XT is very similar though it has a different 
> protocol. It is the mouse that is PS/2 where it uses the keyboard 
> interface with it's own protocol.

That's true. The XT keyboards used a simple monodirectional protocol(the 
keyboard could only send data to the computer). Thus they cannot be used 
with anything but an 8088 PC. With the AT, IBM changed the protocol to a 
bidirectional one, making it possible to send commands to the keyboard, such 
as changing the typematic rate. All PCs since then have used this protocol.

> The PC keyboard now uses a 6 pin mini-DIN plug instead of the original 5 
> pin DIN, this probably started with the PS/2. It is still the same 
> interface.

It did start with the PS/2, although many clone PCs continued to use the 
larger 5-pin plug. At some point during the mid-'90s, all PCs switched to 
the PS/2 plugs.