The YAMAHA PortaSound PSS-790 is adopted with a unique synthesis "Advanced Wave Memory (AWM)' so that you can perform with a wide range of natural to hyper-natural sound qualities. Additionally, the Vector Synthesizer function enables you to carry out time variance of a tone with controlling mixing ratio of any 4 AWM Voices you select. Furthermore, the Auto Accompianment function supports your performance on the keyboard with various music styles such as rock 'n' roll, jazz, Latin, funk, and much more. Moreover, you can record and play back your performance with the Song Memory Function. And other useful functions are also provided. In order to fully enjoy your lifelong musical time spent with the PSS-790, please read the instructions in this Owner's Manual which should provide help and suggestions.