The crossword solutions for the term RUNS PCS are DOS, which stands for Disk Operating System. DOS is a computer operating system developed by Microsoft in 1981 and was the most commonly used operating system on personal computers from the mid-1980s to the early 2000s. It is a single-user, single-tasking system with basic kernel functions that allow users to interact with the computer through a command line interface. DOS is still used today in some embedded systems.