Apple's Chris Espinosa let Steve Jobs design the Mac calculator himself, in 10 minutes

In February 1982, Apple's Chris Espinosa, then 21, wrote a calculator desk accessory for the Macintosh using QuickDraw. This account comes from Andy Hertzfeld's Folklore.org as retold by Ars Technica. Steve Jobs said it was a start but that it stank: the background was too dark, some lines were the wrong thickness and the buttons were too big.

For several days Espinosa applied each day's feedback, and Jobs found new faults each time. So he wrote what he called the Steve Jobs Roll Your Own Calculator Construction Set, exposing every visual parameter through pull-down menus: line thickness, button sizes, background patterns and more.

Jobs sat down and, after about 10 minutes of adjusting, landed on a combination he liked. Hertzfeld implemented the calculator UI a few months later from those settings, with Donn Denman handling the math.

Instead of translating the boss's taste into words, hand him the controls: expose each visual parameter and let him tune it.

Jobs knew what he wanted when he saw it but struggled to say it in words.

Direct manipulation removed the slow cycle of describing, revising and re-reviewing.

Menus for each parameter let Jobs explore the whole design space quickly.

If a stakeholder can't articulate what they want but recognizes it on sight, build a tool that lets them adjust the design directly.

The design shipped with the Mac in 1984 and stayed virtually unchanged through Mac OS 9, until Apple discontinued that OS in 2001. Mac OS X replaced it with a new design, ending a 17-year run, according to Ars Technica.