The original IDE port on a PC motherboard is basically an ISA slot pinout in a different form factor. All an early ISA IDE "interface" consisted of were a few 74-series parts acting as address decoders for 0x170-17Fh and 0x370-137Fh address lines connected to a 40pin IDC socket.

As for the Portable, I recall seeing a unit on ebay a few months ago that had a video adapter in the PDS slot, but the output was a standard DA-15 Macintosh video port.