Load control information into each appropriate register, as shown in the syntax section for the function.The remainder of this chapter describes the MS-DOS Interrupt 21h functions in detail. The reference page for each function provides the syntax, a statement of purpose, any parameter descriptions, and cross-references to any similar or related functions.
All the MS-DOS Interrupt 21h functions share a common interface. To use an Interrupt 21h function, a program should carry out the following actions:
Load control information into each appropriate register, as shown in the syntax section for the function.
Load the function number into the AH or AX register.
Issue Interrupt 21h.
When MS-DOS returns control to a program, that program should examine any appropriate registers for error and return information, as shown in the syntax section for the function.
The reference pages that follow present the MS-DOS Interrupt 21h functions in numeric order.