There are three slot slots of 64 pins each. On the far edge you can see the terminating resistors. The bus drivers are on the right side of the picture. The only thing I haven't decided is whether or not to do 5V compatibility. It doesn't make much sense since there is not a single board in the world for this slot. Other than that it is easier to build 3.3V logic today. On the other side of the scale is keeping hardware compatibility with the CPC6128.