Exhibits At the Museum

This Day in History

Today: September 30, 2016
Log entry describing "first computer bug"

September 9, 1947

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 actual case of bug being found.”