Charles Thacker, one of the lead hardware designers on the Xerox Alto, the first modern personal computer, died of a brief illness on Monday. He was 74.

The Alto, which was released in 1973 but was never a commercial success, was an incredibly influential machine. Ahead of its time, it boasted resizeable windows as part of its graphical user interface, along with a mouse, Ethernet, and numerous other technologies that didn't become standard until years later. (Last year, Y Combinator acquired one and began restoring it.)

"Chuck" Thacker was born in Pasadena, California, in 1943. He first attended the California Institute of Technology in his hometown but later transferred to the University of California, Berkeley in 1967. While in northern California, Thacker began to abandon his academic pursuit of physics and dove deeper into computer hardware design, where he joined Project Genie, an influential computer research group. By the end of the decade, several members, including Thacker, became the core of Xerox's Palo Alto Research Center (PARC) computer research group, where they developed the Alto.

In a 2010 interview, Thacker recalled:

We knew [the Alto] was revolutionary. We built it with the very first semiconductor dynamic RAM, the Intel 1103, which was the first memory you could buy that was less than a 10th of a cent a bit. As a result, we realized we could build a display that was qualitatively better than what we had at the time. We had character generator terminals, and some of them were quite nice. But they were limited in various ways, whereas the Alto had the property that anything you could represent on paper, you could put on the screen. We knew that was going to be a big deal.

At the age of 24, Apple co-founder Steve Jobs famously visited Xerox's Palo Alto Research Center (PARC) and saw an Alto firsthand in 1979. That episode is often credited with being a huge inspiration for the eventual release of the Macintosh five years later. (Like Jobs, Thacker also founded a company in his 20s—in 1969, the short-lived Berkeley Computer Company was born.)

Michael Hiltzik, a journalist who wrote an entire book on the history of Xerox PARC called Dealers of Lightning, said that Thacker was a "key designer."

Hiltzik told Ars:

He was the quintessential hardware guy at a time when designing the hardware was a key aspect of the task. He was a master at designing logic boards when that was the guts of the computer. This was before the silicon revolution. He did all that, and he had built a couple of computers even before the Alto.

Later in his career, Thacker joined Microsoft in 1997 to help establish the company's lab in Cambridge, England. Two years after that, he designed the hardware for Microsoft's Tablet PC, which was first conceived of by his PARC colleague Alan Kay during the early 1970s.

In 2009, Thacker received the Association for Computing Machinery's prestigious A.M. Turing award. According to Thomas Haigh, a computer historian and professor at the University of Wisconsin, Milwaukee, it is "very rare" for a "system builder in industry," as opposed to a theorist or an academic, to be given this honor.

Haigh wrote the following in an e-mail to Ars:

Alto is the direct ancestor of today's personal computers. It provided the model: GUI, windows, high-resolution screen, Ethernet, mouse, etc. that the computer industry spent the next 15 years catching up to. Of course others like Alan Kay and Butler Lampson spent years evolving the software side of the platform, but without Thacker's creation of what was, by the standards of the early 1970s, an amazingly powerful personal hardware platform, none of that other work would have been possible.

In the same 2010 interview, Thacker had some simple advice for young computer scientists: "Try to be broad. Learn more math, learn more physics."