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What Does Molly-Guard Mean?

A molly-guard is a physical shield or barrier that prevents unauthorized or improper access to part of a hardware device. The molly-guard is placed over a button, lever or other control so that less experienced users have more trouble getting to it and it cannot be activated by accident.


Techopedia Explains Molly-Guard

In the urban legends surrounding this term, “molly-guard” is
often attributed to a programmer working on an IBM 4341 mainframe computer.
According to the story, the programmer’s young daughter, who was named Molly, pushed a particularly important control button twice during a given day. Presumably, the
programmer then constructed some type of molly-guard to prevent further

As the term has emerged, it has often been used in conjunction with
the term “big red switch” for a primary power switch, shutdown switch or other primary
control, and may be used on hardware devices or even on industrial machinery.


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Margaret Rouse
Senior Editor
Margaret Rouse
Senior Editor

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.