The answer to the crossword for the term OPPOSITE OF DON'TS is DOS, which stands for Disk Operating System. DOS is a computer operating system developed by Microsoft in 1981. It is a single-user, single-tasking operating system that provides a command-line interface for users to interact with the computer. DOS was the most widely used operating system until the introduction of Windows 95 in 1995. DOS is still used today in some applications, such as embedded systems and booting computers.