Drone view and schematic view can be switched between using SPACE. The drone view is where all drone micro-management is done. It is always has single central drone, and commands can omit the use of numbers to specify drones in this view, because, unless specified, the commands will be executed on the active drone.
In the drone view, the room of the current drone will be the only one lit up no matter if you have drones in other rooms.
In the top left corner, an overview of the current drone shows the name, number, HP left/HP total and the upgrades.