Computers are a machine that changes data according to a set of specific instructions. Computers were first developed in the mid 20th century, (1940-1945). The first computer was the size of a large sized room. There would have been about power taken in that could now power about a hundred personal computers, which are also known as pc. A pc is made up of program, control unit, arithmetic/logic unit (ALU), memory, input/ output, networking, hardware, software, processor. This is what pretty much makes up a computer.