# James Thomson

> James Thomson is an independent iOS and Mac developer in Glasgow, Scotland, best known for PCalc, the scientific calculator he started in 1992 and has been refining ever since. He runs the two-person studio TLA Systems with his wife, having earlier worked at Apple on the Mac OS X Finder and Dock. A fixture of the Apple developer community, he is also a podcast pundit on Relay FM and The Incomparable, a conference speaker, and a Dungeons & Dragons player who photographs squirrels on the side.

- **Role:** Founder and developer at TLA Systems
- **Organizations:** TLA Systems Ltd., Apple (former), University of Glasgow (former)
- **From:** Scotland
- **Nationality:** British (Scottish)
- **Education:** Honours degree in Computing Science, University of Glasgow
- **Known for:** Created PCalc, one of the longest-lived continuously developed apps on the Mac and iOS (since 1992), Created DragThing, a widely used application dock for classic Mac OS, Worked on the Mac OS X Finder and Dock during his time at Apple

## Career timeline

- **early 1980s** — Starts programming on a Commodore 64 (bought after seeing Tron) and BBC Model B
- **1990** — Begins programming the Mac while studying Computing Science at the University of Glasgow
- **1992** — Creates PCalc as a small test project to learn Mac programming
- **1994** — Graduates with an honours degree in Computing Science from the University of Glasgow
- **1994-1996** — Works as a systems programmer in the University of Glasgow's Department of Computing Science
- **late 1990s** — Joins Apple, working on the Mac OS X Finder and Dock
- **2000** — Leaves Apple to become a full-time indie developer, running TLA Systems
- **2008** — Brings PCalc to the iPhone with the launch of the App Store
- **2017** — PCalc celebrates 25 years since its Mac System 7 debut
- **2019** — Apple adds a tip calculator to the Apple Watch, a feature PCalc already had ('Sherlocked')
- **2022** — PCalc turns 30 years old

## Achievements

- Created PCalc, one of the longest-lived continuously developed apps on the Mac and iOS (since 1992)
- Created DragThing, a widely used application dock for classic Mac OS
- Worked on the Mac OS X Finder and Dock during his time at Apple
- Built Dice by PCalc and Twitkitteh as side projects
- Macworld 4.5 Mice award and Macworld Eddy finalist (2002) for DragThing
- MacUser UK Five Mice rating
- Regular Apple developer-community speaker and podcast host on Relay FM

## Latest updates

- **2025-11** — Posted about working on a new version of PCalc for macOS and shipped a PCalc 4.11.1 maintenance update.
- **2022-12** — Celebrated PCalc's 30th anniversary.

## Links

- Website: https://pcalc.com
- Twitter/X: https://x.com/jamesthomson
- Bluesky: https://bsky.app/profile/jamesthomson.bsky.social
- Instagram: https://www.instagram.com/stresspanda/

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Profile page: https://yespress.io/james-thomson
Published by YesPress — https://yespress.io
Last updated: 2026-06-03