If you like me you find yourself wanting an AT2XT adapter, you may have also discovered that they are not too easy to buy pre-made.
Here is one I built on prototype board, using an AT to PS/2 Keyboard cable:
Without the IC Socket on it, it looks like this:
Once the IC Socket is fitted, the tails from the AT to PS/2 Keyboard can be attached like so:
Here is the underside:
The last thing to do is wrap it in heatshrink tube:
A modified and compiled version for PIC12F675 can be downloaded here. I just fired it in with my Universal programmer, plugged it in and it worked perfectly first go.
If yours is using a PIC12F629 like the original design, get the firmware from the original project information page.