MS-DOS uses several Interrupt 21h functions to load, execute, and terminate programs. Programs can use these same functions to manage other programs.
Following are the MS-DOS program-management functions:
| Function | Description | Version |
| 00h | Terminate Program | 1.0 |
| 26h | Create New PSP | 1.0 |
| 31h | Keep Program | 2.0 |
| 34h | Get InDOS Flag Address | 2.0 |
| 4B00h | Load and Execute Program | 2.0 |
| 4B01h | Load Program | 2.0 |
| 4B03h | Load Overlay | 2.0 |
| 4B05h | Set Execution State | 5.0 |
| 4Ch | End Program | 2.0 |
| 4Dh | Get Child-Program Return Value | 2.0 |
| 50h | Set PSP Address | 2.0 |
| 51h | Get PSP Address | 2.0 |
| 59h | Get Extended Error | 3.0 |
| 5D0Ah | Set Extended Error | 4.0 |