how they found *debug*

It is the first computer in the whole world called-Mark1- It is an amazing electromechanical circuit the size of a room. It was built in 1944 in a laboratory at Harvard University. One time a malfunction occurred and no one was able to determine its location and cause. After hours of research, an assistant in the laboratory found the problem. He discovered that there were bug stuck on one of the computer boards and causing a problem. Since That moment any problem happened in computers called debug