For anyone unfamiliar with DOS programming who might be trying to understand the code, you will find it helpful to know that INT 21h makes a call to the DOS API

For anyone unfamiliar with DOS programming who might be trying to understand the code, you will find it helpful to know that INT 21h makes a call to the DOS API, and the value in AH indicates which API function to call, in this case the "display string" function. See https://en.wikipedia.org/wiki/DOS_API https://en.wikipedia.org/wiki/DOS_API