Operating System: Windows XP x64 (Note: might work with other versions of this os.)
B4000 Series PCL Driver for Windows 64 Bit
Install instructions: 1. Double click on 4XX0PC64BPB.exe.
2. Follow the on-screen prompts to extract the driver files
3. Launch Add Printer Wizard
4. When prompted for the Manufacturer and Model click on Have Disk
5. Browse to the following location: C:OKIDATAB4XX0PortuguesePCLWindows64.
6. Click OK