Computers have been around since at least 1613, when being a computer was a skilled profession practised by mathematicians who worked in observatories adding up numbers. When Charles Babbage invented the precursor of the modern computer he called it an Analytical Engine , and when his son improved on the design he called it a Mill , on the basis that mills were complicated technical things and that, like his new machine, they took stuff in at one end and spat different stuff out at the other.