The interface uses ports &F8EF to &FBEF to control the 8255.
Version 1 of the interface does not have a through connector, but a future version will no doubt feature this so more devices can be attached.
The interface also includes a pin header for Compact Flash Card power. The power is attached to Pin 20 which is normally missing on the standard IDE interface specification. An adaptor card attached to the IDE cable would make it possible to use the CF cards (its a shame that the specification did not use the pin in this fashion a long time ago).