Casio CZ/ VZ/ FZ - Pro Series

>yes, indeed the k5k is the masterkeys for my humble gear. Also the vz
>is connected to a midi thrubox. Well i guess the vz is not very
>"up-to-date" and can\ufffdt handle that much midi data ( i often use atari
>editor too ). Maybe i should do reset on it too... As you mentioned it
>- how can i see which OS version is on my unit?

As far as I know, Casio didn't offer OS updates.  The ROM chips inside 
aren't even socketed (I'm pretty sure at least) which would make it very 
inconvenient to upgrade.  This isn't to say that there weren't new OS 
revisions and bugfixes during the life of the VZ, but at least there were no 
official updates, and any changes that were made weren't publicized.