On 8 March 1979, Philips demonstrated for the international press a 11.5 cm Optical Disk and a Compact Disc Audio Player at IEEE. The demonstration showed that it is possible by using digital optical recording and playback to reproduce audio signals with superb stereo quality. Through the co-operation with Sony the final diameter was 12 cm and the initially proposed resolution (accuracy) of 14 bits was increased to 16 bits. With this concept Philips and Sony took the first step in setting a worldwide standard. Philips and Sony set up a joint task force of engineers to design the new digital audio disc. Until 1988, over 400 million CDs have been sold worldwide.