Interrupt Mask Register
| P0 | Input Change Interrupt Mask |
| P1 | Input Change Interrupt Mask |
| P2 | Input Change Interrupt Mask |
| P3 | Input Change Interrupt Mask |
| P4 | Input Change Interrupt Mask |
| P5 | Input Change Interrupt Mask |
| P6 | Input Change Interrupt Mask |
| P7 | Input Change Interrupt Mask |
| P8 | Input Change Interrupt Mask |
| P9 | Input Change Interrupt Mask |
| P10 | Input Change Interrupt Mask |
| P11 | Input Change Interrupt Mask |
| P12 | Input Change Interrupt Mask |
| P13 | Input Change Interrupt Mask |
| P14 | Input Change Interrupt Mask |
| P15 | Input Change Interrupt Mask |
| P16 | Input Change Interrupt Mask |
| P17 | Input Change Interrupt Mask |
| P18 | Input Change Interrupt Mask |
| P19 | Input Change Interrupt Mask |
| P20 | Input Change Interrupt Mask |
| P21 | Input Change Interrupt Mask |
| P22 | Input Change Interrupt Mask |
| P23 | Input Change Interrupt Mask |
| P24 | Input Change Interrupt Mask |
| P25 | Input Change Interrupt Mask |
| P26 | Input Change Interrupt Mask |
| P27 | Input Change Interrupt Mask |
| P28 | Input Change Interrupt Mask |
| P29 | Input Change Interrupt Mask |
| P30 | Input Change Interrupt Mask |
| P31 | Input Change Interrupt Mask |