MS-DOS also provides Interrupt 21h functions for such system-management tasks as setting and examining the system time and date, the state of the Verify flag, and the state of the CTRL+C check flag. The Verify and CTRL+C check flags control how MS-DOS responds to input from programs and users.
Following are the MS-DOS system-management functions:
| Function | Description | Version |
| 25h | Set Interrupt Vector | 1.0 |
| 2Ah | Get Date | 1.0 |
| 2Bh | Set Date | 1.0 |
| 2Ch | Get Time | 1.0 |
| 2Dh | Set Time | 1.0 |
| 2Eh | Set/Reset Verify Flag | 1.0 |
| 30h | Get Version Number | 2.0 |
| 3300h | Get CTRL+C Check Flag | 2.0 |
| 3301h | Set CTRL+C Check Flag | 2.0 |
| 3306h | Get MS-DOS Version | 5.0 |
| 35h | Get Interrupt Vector | 2.0 |
| 54h | Get Verify State | 2.0 |