The Xerox 3700 is a high speed laser printer of the first generation. It has a built in terminal/controller. The 5 1/4" 360K floppy was used to load fonts and emulation software. Most of them were based on the Dataproducts printer interface. It was built on the chassis of a Xerox copier of the times. Usually they have a nice 5-7mw laser tube and power supply in them. I don't know of any other current use for them. Paxton