Fred has introduced us to the Chromatic "B-griff" keyboard in a posting he has put up here:
Do a right-click to open the topic up in a New Tab
http://www.tierce-de-picardie.co.uk/viewtopic.php?f=314&t=5919&p=38510#p38508
I Can't Stop Loving You, played by by Paul Huybrechts. If you haven't already heard it, then go and listen to it! I had never heard of a Chromatic "B-griff" keyboard before, but this recording has completely blown me away. Thanks Fred for posting it! You've made my day!
I had come to the conclusion that the set-up of buttons must be from the Chromatic Button Accordion, but as I have never played one (only a Piano Accordion) I had no idea how the notes were made up. I have come across this YouTube video explaining how the "B-griff" keyboard buttons are made up from the notes on a piano.
The whole idea of having the buttons in this arrangement is so that you can get all the black and white piano notes to fit into about half the space required for a piano. Although I have noticed that the Tyros 4 "B-griff" doesn't have any 'black' buttons, so all sharps and flats look the same as the 'white' notes.
This has answered one question for me. The top two rows of buttons are the same as the bottom two rows of buttons, so that is why those other white buttons go down at the same time as the ones he is pressing. And the reason for this is is to make the 'fingering' easier as you can press a higher button or a lower button to make the note sound.
Here are some more videos showing the chromatic "B-griff" keyboard being played. The YouTube videos will open up on YouTube itself (ie. they are not 'Embedded Videos').
Click the back-arrow at the top after watching each video to get back to this page.
I suppose that Yamaha must make the Tyros 4 with a "B-griff" keyboard as well as the "Piano" keyboard? Maybe for the German and Swiss market?
Hugh