You can find the source code for a program similar to
input.com here. For all I know it may even be the original code for
input.com.
Your OS is not posted, but I'm fairly certain the
debug utility was distributed with the earliest releases of DOS. Follow the directions on how to assemble the code.
Program only works in a MS-DOS Prompt window and not a Command Prompt window. Input is limited to a single word; a string with embedded spaces seems to break the code.
Are we going back to the future?