There are three types: EVT, DVT.
OS 3.6 introduces new security features to prevent CAS software from being run on non-CAS software.
Unfortunately, these features have been so poorly designed that they will brick DVT prototypes.
If you have discovered a previously undiscovered prototype, try to install Ndless on it.
Then, use Polydumper to try and extract the image. Finally, send that image to Critor with as much info as you can find about the unit.
- Source: CNCalc - Nspire Touchpad DVT