David Jaggar


The groundbreaking accomplishments of David Flynn and David Jaggar while working at Advanced RISC Machines (ARM) during the 1990s created the foundations that launched the system-on-chip market with microprocessors that proliferate today’s digital devices such as smartphones and portable computing devices and continue to play an important role in the evolving Internet of Things. Based on reduced instruction set computing (RISC) processing, their designs use less energy, making them perfect for battery-powered and fanless devices. Flynn and Jaggar first collaborated on designing versatile development boards and firmware to enable software development. Together they defined a new ARM architecture directed toward embedded control, on-chip debug, and high-speed multiplication for signal processing that resulted in the ARM7 microprocessor family fundamental to successful embedded control designs. Jaggar developed the Thumb instruction set architecture to provide substantial code density improvements over processors with single instruction sets, which were compromised between high-performance and low system cost and power consumption. Adding Thumb as a second instruction set to the ARM architecture allowed lower cost and power consumption by utilizing the compressed Thumb instruction set for the vast majority of code while still allowing peak performance for critical code using the ARM instruction set. This technique reduced overall code size by 30% and increased performance from low cost, slower memories by 50%, and was first used in the ubiquitous ARM7TDMI. Over 100 billion devices now feature Jaggar’s architectural innovation, which has been particularly successful in mobile phone designs. Flynn then led the ARM program that evolved this design from a full-custom transistor layout macrocell to be fully synthesizable to deliver fast time-to-market intellectual property. Flynn drove the development of the first generation of ARM’s Advanced Modular Bus Architecture that became the on-chip industry’s standard interconnect, AMBA, which enabled the vast ARM System-On-Chip (SOC) ecosystem by flexibly interfacing the ARM7TDMI to hundreds of silicon partner's peripheral libraries. Jaggar’s Architecture Reference Manual and definitions have allowed partners such as Apple to develop their own ARM implementations while still adhering to a global standard, allowing ARM to license both specific implementations and the architecture itself. Flynn’s and Jaggar’s innovations have changed the shape of an industry, bringing together systems, software and application design, electronic design automation, semiconductor foundry, electronics, and consumer manufacturing companies to work more successfully and more efficiently to further enable the digital and information revolution around the world.

An IEEE member, Jaggar is a former ARM Fellow currently residing in Canterbury, New Zealand.