This morning’s Observer column

In the normal course of events, a Siemens Simatic Programmable Logic Controller PLC would not be of interest to anyone other than a hardcore industrial process engineer. It’s a small, dedicated computer used to control the operations of specialised machinery in a wide range of manufacturing industries. Since June, however, the Siemens controllers have become a topic of intense interest to people like journalists and policymakers who, in normal circumstances, have difficulty controlling a microwave oven.

How come? The reason is the Stuxnet worm, a piece of computer malware as malicious software is called, that has caused a huge stir in the mainstream media…