A lot of Olympus dictaphones are provided without a physical manual which is not stored on the olympus.com website. You can download the manuals here: Olympus Dictaphone Manuals. This includes the Olympus DM450 and DM550 which are located near the bottom of the page.
Tag: Manual
SenseView D600 and D700 User Manuals
Manuals for the SenseView products in .doc format SenseView D600 User Manual SenseView D700 User Manual