RESULT OF VALIDATION OF INTERFACE POLARITIES
After I powered up and checked all the polarities, it was clear that all the status signals including Index Marker were inverted polarity. I updated my code to run an interrupt routine on the falling edge of IM and to treat the status bits as inverted. At this point I am ready to begin testing the code.
WIRING AND CONSTRUCTION OF EXTERNAL INTERFACE BOX PROGRESS
I wired up the external interface to the shield, inserted it on the Arduino and started work on the final mounting and some outside connections/components. Specifically, I need the USB cable to exit the box, two connectors to provide 5VDC, a pushbutton to toggle the End of File (EOF) status, and an LED to display when EOF is active.
I made use of my nibblers, hole punch and drills to add the components on the top plate, after which I can close up the box and test. Once again, I had to leave the shop early to perform tasks related to my move-in tomorrow.