The kettle boiled — the network went down: how a cup of tea helped fix a computer system

An engineer at Norsk Data has solved the mystery of the constant crashes of the Wordplex word processing system in an unusual way.

The story happened in the 80s. Kevin, an engineer at Norsk Data, a Norwegian company that specialized in minicomputers, faced an unusual problem. He was called to a client’s office to fix a Wordplex word processing system that kept crashing. This 8-bit Z80 processor system consisted of a host computer with a 10-20 MB hard disk and a 5¼-inch disk drive, green monitor and two terminals connected via RS-232 without their own data storage.

Despite two previous visits, Kevin was unable to solve the problem. Suspecting a problem with the power supply, he brought an electrician with him this time. When they arrived, the customer offered them tea. This moment became the key to the investigation.

As soon as the kettle was turned on, Kevin heard two sounds: the kettle clicking and the Wordplex system shutting down. Suddenly, everything fell into place — the cause of the malfunction was in the power grid.

The electrician quickly found out the cause. It turned out that the client had recently modernized the wiring, but did it poorly. Under heavy load on the network — for example, when the air conditioner was turned on, elevators were running, and all the employees came in — the wiring could not withstand it. Turning on the kettle was the last straw that overloaded the power grid and shut down the computer system.

It’s important to note that Wordplex was a very demanding system for power supply stability. Its clustered architecture with a mainframe and connected terminals made it vulnerable to sudden voltage changes. When the power grid was overloaded, it led to data loss and disruptions to the entire word processing system.

Thanks to this discovery, Kevin and Norsk Data absolved themselves of responsibility for the hardware problems. The problem was not in Wordplex’s equipment, but in the client’s power grid.

Source: TheRegister