Charles Babbage 'The grandfather of modern computer' had designed two computers:

The Difference Engine: It was based on mathematical principle of finite differences and was used to solve calculations on large numbers employing a formula. It was also used for solving trigonometric and polynomial functions.

The Analytical Engine by Babbage: It was a common purpose-computing device that could be used for executing any mathematical operation automatically.  Fundamental features of this analytical engine were:

• It was a general-purpose programmable machine.
• It had automatic sequence control so enabling programs to change its sequence of operations.
• The provision of sign checking of result existed.
• A mechanism for reversing or advancing of control card was permitted so enabling execution of any desired instruction. In other words Babbage had created the branching and conditional instructions. Babbage's machine was basically the same as modern computer. Unfortunately Babbage work couldn't be finished however as a tribute to Charles Babbage his Analytical Engine was completed in last decade of 20th century and is now exhibited at Science Museum at London.

The next notable efforts in the direction of computers were electromechanical. Zuse employed electromechanical-relays that could be either closed or opened automatically. So the use of binary digits rather than decimal numbers began in computers.