How many applications is your computer running right now? If the answer is more than one, then you’re already well ahead of most personal computer of the 1980s. Early microcomputer operating systems like CP/M and MS-DOS could only run a single application at a time. There were certain hacks to try and get around this limit–such as RAM-resident software–but the typical 8- or 16-bit PC lacked the processing power to multitask even if the operating system could technically support it.