Toshiba products play an active role, be it in computing, controlling, powering, or communicating -- transporting, cooking, playing, or even elevating. The company's portfolio includes personal and professional computers (notebook PCs, servers), telecommunications and medical equipment (mobile phones, X-ray machines), industrial machinery (power plant reactors, elevators), consumer appliances (microwaves, DVD players), electronic components (electron tubes, batteries), and semiconductors. Its portfolio also includes air traffic control and railway transportation systems. Customers outside of Japan account for about half of Toshiba's revenues.