A magnetic disc unit includes a rotating disc type magnetic disc having an outer periphery, and a carriage arm linked to a head support mechanism for a recordingreproducing head. A computing device may determine a first remnant swap for blending fixed rate components of the plurality of swaps using the fixed rate. A gap is formed by removing part of connecting members, rotatable about the incident point and the detection point, around the subject head top portion. The platen may include a visual identifier for identifying a portion of the field of view of the image capture device. The power control circuit turns on the switching circuit for a specified period when power supply to the voltage controlled oscillation circuit is started.