If used for four computers to share a parallel printer, it is plug and play with no software to install. If used for one computer to access four printers, the bundled software creates Virtual Parallel Ports to provide fully automatic switching between printers. It has built-in microprocessor for high speed bi-directional communications. Provides push button & hot key for printer selection. This switch supports all parallel printers including high speed IEEE1284, Bi-tronics & centronics as well...