OqtaDrive can coexist with actual hardware Microdrive units. If you want to combine OqtaDrive with hardware Microdrive units, then there are essentially two choices for placing the OqtaDrive adapter - either at the end of the drive chain or at the start. Here are a few considerations and pros & cons for both options. Spoiler alert: first in chain is best…

Last in Chain

Pros

• simple - adapter just plugs into the Interface 1, QL, or Microdrive unit edge connector
• requires just one edge connector plug
• no hardware modifications needed

Cons

• hardware Microdrive units are always upstream of the adapter, and cannot be turned off or mapped into different slots; on the QL for example this means that OqtaDrive can only emulate mdv3 through mdv8

First in Chain

Pros

• hardware Microdrive units can be freely moved as a group within the chain, or turned off completely

  To take advantage of drive mapping, you need to route the COMMS_OUT signal from the adapter to the COMMS input of the first of the hardware drives, and make a couple of settings in the config section at the top of arduino/oqtadrive.ino. Tom Dalby’s Micro and Standalone PCBs (see build section) are prepared for this.

Cons

• requires an additional edge connector (plug) for connecting hardware Microdrive units; alternatively, the adapter can be installed into an Interface 1 or QL, but cannot be used with other machines in that case
• for the QL, this requires modifying the hardware