INT 2F U - DOS 5+ - ROM(Read-Only Memory) A memory for program storage which may not be changed by the program as it runs. COMMAND.COM INTERFACE AX = 5501h Return: ??? Note: used to determine whether the caller is the first instance of ROM(Read-Only Memory) A memory for program storage which may not be changed by the program as it runs. COMMAND.COM SeeAlso: AX=5500h