Just a quick addendum to this. Here's a PDF of the schematic in that adapter board. In the photo from the previous post the left board is an Automotive Networking Board from Microchip that can take various processors and Click modules for external interfaces. It also has a 2x25 header for a bunch of the processor pins. That's in the top left part of the drawing. Below that marked PIC18 is the cable that goes to the 40 pin PIC processor socket. In between level translation from the PIC32 3.3V to the PIC18F series 5V. Not all level translation devices are used.
The software ported easily and that's all that was required to upgrade an 8 bit processor to a 32 bit without any extra 'features' The level translation and pin translation is the middle board in the photo and on the far right my ELS.
This is a large version of Henrik Olsson's dsPIC upgrade for the HP_UHU which I really do recommend. It can handle higher resolution encoders and step rates.