In this post, the author demonstrates how to use the MS-DOS and Windows 98 debugger program named DEBUG.EXE to work with assembly language instructions and machine code. They provide examples of creating small programs that print characters to standard output, such as a 7-byte program that prints the character “A” and a 23-byte program that prints the string “hello, world”. The author also discusses using the debugger for scripting, disassembling binary executable files, and compares using INT 20 and RET instructions for program termination. The DOS debugger, although limited, offers a helpful tool for basic assembly language programming without the need for additional software.
https://susam.net/programming-with-dos-debugger.html