Tim King, whose port of Tripos became AmigaDOS, has died
by The RetroMake desk 26 October 2026
The Cambridge-trained programmer whose 68000 version of the Tripos operating system became the DOS of the Commodore Amiga died at the end of July, his family told amiga-news.de. He went on to co-found Perihelion and to found the ISP UK Online.
What we know
- Dr Tim King died at the end of July 2026; his family confirmed the death to amiga-news.de, which reported it on 11 August 2026.
- The Register gave his age as 71 in an obituary published on 18 August 2026, correcting a first version that said 70.
- King joined MetaComCo in 1984, and the 68000 version of Tripos he brought with him became AmigaDOS when Commodore's own operating system for the Amiga fell behind schedule.
- He co-founded Perihelion Software, maker of the Helios operating system for Transputer machines, in 1986, and founded the internet service provider UK Online in 1994.
Dr Tim King, the programmer whose 68000 version of the Tripos operating system became AmigaDOS, died at the end of July 2026. His family confirmed the death on request to amiga-news.de, which reported it on 11 August. The Register, in an obituary by Liam Proven published on 18 August, gave his age as 71, and has since corrected its first version, which said 70.
Tripos
King studied computer science at the University of Cambridge and received his PhD there in 1979, according to amiga-news.de. Tripos came out of the university's Computer Laboratory. Martin Richards, who also created BCPL, the language Tripos was written in, says on his university page that the system was developed "by a group of research students and myself starting in 1977" as a light, portable multitasking operating system in BCPL and assembly language.
Accounts of King's part differ. amiga-news.de says he developed Tripos while still a student. The Register says Richards wrote it, and that King's contribution was the port from the DEC PDP-11 to the Motorola 68000, made while he was a researcher at the University of Bath.
The backup DOS
In 1984 King joined MetaComCo, a Bristol company that sold 68000 development tools, and took the 68000 Tripos with him. Commodore's own operating system for the Amiga, known as CAOS, was behind schedule, and the company turned to MetaComCo. Andy Finkel, then software manager at Commodore-Amiga, wrote in 1988 that "what we now call AmigaDOS was really the backup DOS", based on Tripos and "converted with amazing speed by Metacomco's Dr. Tim King and his band of programmers."
The Amiga kept Carl Sassenrath's Exec kernel and the Intuition windowing system; King joined the BCPL code to both, The Register reports. What users met on the command line was Tripos. Michael Steil's 2009 comparison of the two manual sets shows that the DOS calls, the shell and its commands, the "hunk" executable format and the original file system were essentially those of Tripos, and that the AmigaDOS manual was largely the Tripos manual with the name changed. The BCPL code was rewritten in C for AmigaOS 2.
Perihelion and UK Online
After MetaComCo, King moved to Perihelion Software, founded in 1986. The Cambridge Computer Laboratory's roll of companies started by its graduates and staff lists him as co-founder, and amiga-news.de says he founded it; The Register describes Perihelion as a start-up created by Jack Lang. There King drew on Tripos for Helios, a Unix-like operating system for machines built from many Inmos Transputers. Neither Helios nor the Transputer became a commercial success.
In 1994 he founded UK Online, which the Cambridge roll calls the country's first full internet service provider. Easynet bought it in 1996, and the brand lasted until Sky closed it in 2011. King later worked as a technical consultant, latterly through TJJ Ltd, the company he ran with his wife and business partner, Jessica, The Register reports. It also quotes his own summary of the Amiga years: "As a result I have the distinction of having written software used by over 2 million users."