By the end of 1990 the Acorn RISC Machine, which was designed in Britain, was practically extinct. The parent company, Acorn, was down a very dark financial alley, and the remnants of the design team were cast out to fend for themselves, equipped with about 18 months of financial rations from Apple, and a really rather odd microprocessor design. When Dave Jaggar joined ARM a few months later, with the ink not quite dry on his Master's Thesis, he thought perhaps he'd made a dreadful mistake. However, after twelve months he was given free range to start the ARM architecture afresh, and the new Advanced RISC Machine, as the company was now named, was born. Over the next 8 years he worked out a little bit about computer architecture, in the same way that a 17th century surgeon understands anatomy, then he was made the first ARM Fellow, so he promptly retired back to New Zealand to raise his children. As it's the 25th anniversary of his quite successful Thumb compressed instruction set, and his children have all left home, he's been told it's about time he explained himself.
During Dave's nine years at ARM he authored the ARM Architecture Reference Manual, properly defined the architecture for the first time, including a second integer instruction set, Thumb, which enabled ARM's success in embedded control. He also added on chip debug so ARM cores could be buried in a SoC, defined a new floating point instruction set, and rebuilt the system architecture so it could run an OS properly. Founding Director of the ARM Austin Design Center, he holds 29 US patents and is a co-recipient of the 2019 IEEE/RSE James Clerk Maxwell Medal (with David Flynn, who designed the ARM AMBA bus).