Many PCs from '80s and '90s had keyhole locks, right next to the Turbo and Reset buttons. What was it for?

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Your 486 had a key. Do you remember what it was for?
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Many PCs from '80s and '90s had keyhole locks, right next to the Turbo and Reset buttons. What was it for?
Your 486 had a key. Do you remember what it was for?
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