The next important effort in the direction of devising an electromechanical computer was made at Harvard University mutually sponsored by IBM and Department of UN Navy, Howard Aiken of Harvard University created a system known as Mark I in 1944. Mark I was a decimal machine means that computations were performed employing decimal digits.

Some of you should have heard a term known as 'bug'. It is mostly used to denote errors in computer programs. This term was invented when one day a program in Mark-I didn't run accurately because of a moth short-circuiting the computer. Since then moth or bug has been linked with problems or errors in computer programming. So process of eliminating error in a program is termed as 'debugging'.

The common shortcomings of these electromechanical and mechanical computers were: 

• Inertia/Friction of moving components limited speed.
• Data movement using liners and gears was very unreliable and difficult.

Change was to have a storing and switching mechanism with no moving parts. The electronic switching device 'triode' vacuum tubes were used so first electronic computer was born.