William (Bill) Lamie (born 15 July 1961) is an American software engineer. He is known as the author of the Nucleus, ThreadX and PX5 real-time operating systems (RTOS).^[1][2][3]

Lamie was born in Hawaii and grew up in Southern California and then Michigan. Bill started his Computer Science studies at Central Michigan University (CMU). His father Edward Lamie was a Computer Science professor and department head at CMU, where he first realized that Computer Science was his passion. In 1985, he completed his Bachelor of Science in Computer Science (BSCS) degree from San Diego State University (SDSU).

Lamie's area of expertise within the field of Computer Science lies in real-time operating systems (RTOS). His interest in this field was sparked during his initial employment at Digital Wizards, a San Diego–based company. Digital Wizards provided the US Navy an RTOS called Executive Operating System (EXOS), of which he was a major contributor. After EXOS, he worked for Scientific Atlanta and then started consulting in the real-time, embedded arena.

In the late 1980s Lamie created the Nucleus RTOS and co-founded Accelerated Technology (ATI), which is now part of Siemens Embedded. The Nucleus RTOS comprised two variants, namely Nucleus RTX and Nucleus PLUS. Nucleus PLUS offered dynamic object creation/deletion capabilities and a more extensive range of functionality compared to Nucleus RTX. As of 2023, the Nucleus RTOS has been employed in approximately 3 billion devices.^[4] In 1995, he made the decision to depart from Accelerated Technology.

In 1997, Lamie created a new real-time operating system known as ThreadX and co-founded Express Logic, a software development company. In 2019, Microsoft acquired Express Logic, including the ThreadX technology.^[5][6] ThreadX gained recognition in the embedded industry for its advantages in terms of size, performance, and simplicity when compared to the Nucleus RTOS. According to VDC Research, ThreadX has been deployed in nearly 11 billion instances. Following the acquisition, Microsoft rebranded the technology as Azure RTOS.^[7]

In 2022, Lamie left Microsoft and introduced a new RTOS known as the PX5 RTOS. The PX5 RTOS differentiates itself from ThreadX by leveraging data encapsulation and Pointer/Data Verification (PDV) techniques, resulting in notable benefits in terms of size, speed, and security. Moreover, the PX5 RTOS features a native implementation of the POSIX pthreads API, an IEEE standard, enabling code sharing across embedded Linux platforms and reducing the need for additional engineering training. Subsequently, in January 2023, he established a new company named PX5.^{[8][9][10][11][12][13][14]}