HP 3550 - Manual (Page 60)

USB configuration
All printer models support USB connections. The USB port is on the back of the printer.
Connecting the USB cable
Plug the USB cable into the printer. Plug the other end of the USB cable into the computer.
1
2
USB port connection
1 USB port
2 USB connector
NOTE You cannot connect the printer to one computer using the parallel cable and to another
computer using the USB cable. If you connect both types of cables, the USB disables itself.
48 Chapter 3 I/O configuration ENWW