Exhibits At the Museum

This Day in History

Today: April 21, 2014
Grace Hopper

September 9, 1945

First instance of actual computer bug being found.

At 3:45 p.m., Grace Murray Hopper records the first computer bug in her log book as she worked on the Harvard Mark II. The problem was traced to a moth stuck between a relay in the machine, which Hopper duly taped into the Mark II's log book with the explanation: First instance of actual computer bug being found.