Q. The ‘IBM-DOS’ is a:
Answer: Single user operating system
Notes: Alternatively referred to as PC DOS, IBM DOS is a text-based operating system similar to Microsoft’s DOS, but only sold by IBM. DOS is a single-user, single-tasking operating system with basic kernel functions that are non-reentrant: only one program at a time can use them and DOS itself has no functionality to allow more than one program to execute at a time.