if both DOS and WINDOWS are operating systems then is it possible that a computer only has WINDOWS and no DOS?

Answer 1

yes, its possible that a computer has no DOS windows was DOS before but now it changed the new one is called BIOS...

INFO ON DOS:
DOS commonly refers to the family of closely related operating systems which dominated the IBM PC compatible market between 1981 and 1995 (or until about 2000, if Windows versions 95, 98, and Me are included) : PC-DOS, MS-DOS, FreeDOS, DR-DOS, Novell-DOS, OpenDOS, PTS-DOS, ROM-DOS and several others. They are single user, single task systems. MS-DOS from Microsoft was the most widely used. These operating systems ran on IBM PC type hardware using the Intel x86 CPUs or their compatible cousins from other makers. MS-DOS is still common today and was the foundation for many of Microsoft's operating systems (from Windows 1.0 through Windows Me). MS-DOS was later abandoned as the foundation for their operating systems.

AND BIOS:

BIOS, in computing, stands for Basic Input/Output System also incorrectly known as Basic Integrated Operating System. BIOS refers to the software code run by a computer when first powered on. The primary function of the BIOS is to prepare the machine so other software programs stored on various media (such as hard drives, floppies, and CDs) can load, execute, and assume control of the computer. This process is known as booting up.

BIOS can also be said to be a coded program embedded on a chip that recognises and controls various devices that make up the computer. The term BIOS is specific to personal computer vendors. Among other classes of computers, the generic terms boot monitor, boot loader or boot ROM are commonly used.

The term first appeared in the CP/M operating system, describing the part of CP/M loaded during boot time that interfaced directly with the hardware (CP/M machines usually had a simple boot loader in ROM, and nothing else). Most versions of DOS have a file called "IBMBIO.COM" or "IO.SYS" that is analogous to the CP/M disk BIOS.

Answer 2

DOS is the older operating system. Originally Windows was really a DOS system, it used the DOS operating system. Now, it is an operating system in its own right. You can have more than one operating system on a computer and select which one to run at boot time. There is no point in having Windows and DOS as Windows can emulate DOS. You could have Windows and Linux.

Answer 3

Yes. Windows is now the operating system. The old Windows, 3,XX series just rode on DOS. The Windows ( versions have a sort of DOS as they had to let people with DOS programs have a way to run them until they could be converted over. You can still go to a DOS type screen in XP, but it is actually Windows that is fooled into thinking it is DOS. I have three small DOS programs on a floppy that I run to figure my utility bill and other things.

Ron