| 31-4 | Reserved | 0 | Reads return 0. Writes have no effect. |
| 3-0 | MKEY2 | | Mode Key to select operation for VIM Output Compare Diagnostic. |
| Read in User and Privileged mode. Write in Privileged mode only. |
| 0 | Read: Returns current value of the MKEY2. |
| Write: Active Compare Lockstep mode. |
| 6h | Read: Returns current value of the MKEY2. |
| Write: Self-test mode. |
| 9h | Read: Returns current value of the MKEY2. |
| Write: Error Forcing mode. |
| Fh | Read: Returns current value of the MKEY2. |
| Write: Self-test Error Forcing mode. |
| Other values | Note: It is recommended to not write any other key combinations. Invalid keys will result in switching operation to lockstep mode. |