How the 1969 AL1 Microprocessor Settled a Silicon Valley Court Drama

September 07, 2023 by Jake Hertz

At the center of one of the largest early court cases in Silicon Valley was the AL1 device, the brainchild of Four-Phase Systems founder Lee Boysel.

In the storied history of the computing industry, Intel's 4004 microprocessor often steals the spotlight as the first commercially available microprocessor. In the shadow of this fame is a lesser-known but equally groundbreaking marvel: the AL1, developed by Four-Phase Systems. 

This chip, a brainchild of Lee Boysel, has been a subject of debate, intrigue, and courtroom drama. Let's journey back in time to explore the AL1's fascinating history, its revolutionary architecture, and its indelible mark on the computing world.


The Man Behind the Machine: Lee Boysel

The story of the AL1 begins with the story of Lee Boysel. Starting his career at Fairchild Semiconductor in 1966, Boysel was considered a visionary who saw the untapped potential of Metal-Oxide-Semiconductors (MOS). 


Lee Boysel

Lee Boysel. Image used courtesy of the University of Michigan

While at Fairchild, Boysel designed a 256-bit RAM and an 8-bit full adder, laying the groundwork for what would become his magnum opus. In 1968, Boysel left Fairchild to build a single-chip computer that could rival industry giants like IBM. Thus, Four-Phase Systems was born, named after the innovative four-phase clocking system Boysel designed.


The AL1: A Masterpiece in Silicon

The first major offering to come out of Four-Phase Systems was the AL1, an 8-bit processor that featured a comprehensive set of eight registers, including the Program Counter (PC).


The AL1 microprocessor

The AL1 microprocessor. Image used courtesy of the University of Michigan

At its core was a full 8-bit Arithmetic Logic Unit (ALU) responsible for performing various arithmetic and logical operations. The AL1's architecture also featured a four-phase clocking system, a design choice that significantly increased chip density and performance.

What really set the chip apart was its speed. Clocking in at around 1 MHz, it was nearly ten times faster than its contemporaries. The chip consisted of over 1,000 gates and approximately 4,000 transistors, all packed into a die size of 3.3 mm × 3 mm. 


The Courtroom Drama

The debate around the AL1 began when TI patented the TMX 1795 and sued multiple companies for patent infringement in a case colloquially known as "TI v. Everybody." The stakes were high; if TI won, it could potentially monopolize a significant portion of the burgeoning microprocessor market through licensing fees and legal leverage.

Defending his work in court, Boysel showed that the AL1 could operate as a standalone microprocessor, effectively establishing it as "prior art," predating the TMX 1795. This demonstration undermined TI's claim to having invented the concept in their patent, thereby weakening their legal position. If a technology or concept is shown to have existed before a patent was filed, the patent can be invalidated.

Boysel proved this by building a computer model embedded with an authentic, date-stamped 1969 AL1 chip. Even though the AL1 cannot be technically considered a microprocessor because it contains only an ALU and a register with no control, Boysel used it as such in a demonstration prior to the 1995 TI trial—and it proved to run 20 times faster than Intel and TI chips.  

“Faces went white; the place turned into chaos,” Boysel recounted of the event. “They just realized that they’d lost, and it was over." 


A computer that housed the AL1 microprocessor

A computer that housed the AL1 microprocessor. Image used courtesy of the University of Michigan

The AL1's role in this legal battle had a profound impact on the industry, shaping patent strategies and highlighting the importance of prior art in intellectual property disputes. 


The Legacy of the AL1

Despite its groundbreaking architecture and capabilities, the AL1 remains an unsung hero. While it powered Four-Phase Systems' IV/70, the company's first commercial computer product, it never gained fame comparable to Intel's 4004 microprocessor. By 1973, Four-Phase Systems had installed over 350 systems and 4,000 terminals worldwide, yet the AL1's story remained confined to the corridors of the company. In 1981, Four-Phase Systems was sold to Motorola for a $253 million stock deal.

While the AL1 itself did not become a commercial success, its demonstration in court altered the trajectory of microprocessor patent litigation, thereby influencing the industry's legal landscape for years to come. The AL1 serves as a critical example of how technological innovation and legal maneuvering can intersect to shape the course of an industry.