If the Oki print driver is installed in Windows and a test page is printed (or anything is printed from Windows) the printer language will change to Hiper-W emulation which is incompatible with DOS. In order to correct this, you must delete the Oki driver and add the PCL driver from the Oki cd-rom. In the Printers control panel, select add printer and have disk. Use the path of PCLWIN95 on the Oki cd-rom. It is the only driver in the PCLWIN95 directory of the cd-rom. The driver in the root of the cd won’t work. You must use the PCL driver. After you print a test page and turn off spooling for dos, it should now be in the correct mode (HP LaserJet 4P), which is the default.