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Steve Jobs Tuned the Original Mac Calculator in 10 Minutes Using a Prototype Tool

A parameterized interface built by Chris Espinosa let Jobs adjust visual settings directly, illustrating an early form of visual design tooling.

Overview

  • New retrospectives from Ars Technica and 9to5Mac recount the episode from Andy Hertzfeld’s recollections.
  • Espinosa’s “Construction Set” exposed line thickness, button sizes, and background patterns through pull-down menus, which Jobs tweaked for about 10 minutes.
  • Hertzfeld implemented the interface months later using Jobs’ chosen parameters, while Donn Denman wrote the calculator’s mathematical functions.
  • The resulting design shipped with the 1984 Macintosh and remained largely unchanged through Mac OS 9, lasting about 17 years.
  • The account highlights Jobs’ preference for judging work through direct interaction rather than verbal specifications.