Internal design of OM-1 (right), and its top view reveals the placement of the galvonometer where it would normally be the shutter speed dial.
History: Yoshihisa Maitani leading his group in designing the OM system: Cameras, lenses, flash, motor drive, close up lenses, and filters, carrying cases. If you have any of these at your collection, the carrying case is the first one to turn into powder, the camera itself needs a complete overhaul.
Related
Article in
Optomex
Download Optomechanix July-Sep 2018
for a brief history of camera design at Olympus, and OM1 design