Hi Scott and Andrea,

I expect the Tyros Operating System (OS) to be a little part of the 40 Mb. (2 of 3 Mb ?)

In fact the menu structure and tasks the OS has to handle is VERY simple and could not take more than the 2 or 3 Mb's.

The rest of the instrument functions as soundgenerating software, display, controlpanel, etc. is done by dedicated chips (IC's)..... in a normal situation

It is possible Yamaha's upgrades contain much more than an OS... perhaps styles, DSP-programs, sounds (samples), graphic (display) software, wallpapers etc.... ?

Sometimes it is cheaper to let software do a 'job' than to develop/create dedicated (custom-made) IC's. Software has less weight.....and the Tyros is a "leightweigt" in a few ways ha !

Roel