-> there's 5v on the mouse socket. the problem more likely is that the printer
-> isn't built with software that lets it communicate with a mouse socket, while
-> the mouse is. and/or that your operating system can't handle printers attached
-> to the mouse port.

My old Delorme Serial GPS unit can get it's power from a PS/2 port. 
Some USB hard drive cases come with a special cable with a PS/2
connector to provide the power for the Hard Drive. NOT all external
USB Hard Drives will work o nthe "Power Limited" feed to the standard
USP port. Particualrly the 3 1/2" drives. My 4 gig 2 1/2"(Formet Laptop
Drive) works great o nmost USB ports. But sometimes I need my adapter
cable. It happens to use a Second USB port for additional power so only
works with Powered USB hubs.
--- Platinum Xpress/Win/WINServer v3.0pr5