1. Mechanical calculators, punch-card machines and slide rules illustrate the earliest forms of computers.

2. He used a small mechanical calculator to solve each problem, a laborious process later rapidly accomplished by computer.

3. The engine would have used loops of Jacquard's punched cards to control a mechanical calculator — the forerunner of today's methods of computer programming.

4. Who attempted to build something called a "Difference Engine" during the first half of the nineteenth-century, a kind of mechanical calculator designed to compute various sets of numbers?

5. The first "computers" were indeed people. The word originally meant an individual who solved equations, often using a mechanical calculator.