Nov 13, 2025 20:00:00
The Macintosh 128K , released by Apple Computer in 1984, was equipped with System 1.0 , the earliest version of the Mac OS. System 1.0 included a desktop calculator app, which is said to have been designed by Apple co-founder Steve Jobs.
Folklore.org: Calculator Construction Set
https://www.folklore.org/Calculator_Construction_Set.html
Original Mac calculator design came from letting Steve Jobs play with menus for 10 minutes – Ars Technica
https://arstechnica.com/gadgets/2025/11/original-mac-calculators-design-came-from-letting-steve-jobs-play-with-sliders-for-ten-minutes/
Chris Espinosa, Apple’s eighth employee, joined the company at the age of just 14 in 1976 after meeting with Jobs at a PC store where he worked part-time when Apple was still located in Jobs’s family garage. Espinosa is still employed at Apple at the time of writing and is known as the company’s longest-serving employee.
by Meredith Espinosa
Espinosa, who wrote the Apple II reference manual while attending high school and college, was persuaded by Jobs, ‘You can always go back to school, but now is your chance to be involved in the development of the Macintosh.’ He dropped out of the University of California, Berkeley, in 1981. He became the Macintosh documentation manager at Apple and created documentation for
QuickDraw , the Mac OS drawing API.
While writing this document, Espinosa was excited by the idea of a ‘ desk accessory ,’ which had not yet been implemented at the time, and developed a calculator as a demo program. After much trial and error, Espinosa completed the calculator and went to show Jobs the newly created calculator app.
However, Jobs said, ‘Well, it’s not a bad start, but fundamentally it’s no good. The background color is too dark, the line thickness is wrong in some places, and the buttons are too big,’ and ordered revisions. Espinosa said he would revise the design until Jobs was satisfied, and he repeatedly showed it to Jobs, but each time he continued to find new flaws.
So instead of showing a new version of the calculator, Espinosa decided to prepare a program called ‘the Steve Jobs Roll Your Own Calculator Construction Set.’
In this program, the calculator’s graphic attributes were parameterized, allowing users to freely choose line thickness, button size, background pattern, etc. When Jobs saw the program that Espinosa brought, he immediately began tweaking the parameters. Jobs worked with the program for about 10 minutes, and the calculator eventually settled on a design that Jobs liked.
This design was adopted almost unchanged for System 1.0, which was included in Mac OS from its release in 1984 until Apple stopped development of Mac OS 9 in 2001.
