K2000 /K2000S that the serial number starts with 91,92,or 93 are Calvin
K2000 /K2000S that the serial number starts with 21 are Janis



K2000R /K2000RS that the serial number starts with 11 are Calvin
K2000R /K2000RS that the serial number starts with 22 are Janis



The Janis chip replaces the Calvin chip. This is the "sample fetch" chip used by the K2000. Kurzweil made the change as part of a manufacturing update. In terms of the results for the end user, there is no difference in features or capability. However, because of differences between the two chips, the Janis chip requires a slightly modified circuit board and engine firmware. You can tell what kind of board you have by whether or not there is a J after the version number displayed on power-up. If you are updating your unit to a new version of the operating system, you will need to know which version you have so that the proper engine firmware will be sent. There is no damage caused by installing one version of firmware in the opposite machine; it will simply not work.