This is David Hansel’s Disk Controller expansion board for the 26-pin bus. You can read more about this board at David’s Github.
This includes the circuit board and all necessary components, including an ATMega328p programmed with MITS firmware, to replicate the function of the MITS 88-DCDD 8-inch controller, which can be used with an authentic SA-800 8″ drive (hard to find) or used with a more readily available TEAC 5.25″ drive. A brief assembly guide is provided, but you should also visit the Github and OSHWLab pages for construction.
You will need to source the following parts on your own (links provided for your convenience):