John Ellenby, a British-born computer engineer who played a critical role in paving the way for the laptop computer, died on Aug. 17 in San Francisco. He was 75.

His son Thomas confirmed the death but said the cause had not been determined.

Mr. Ellenby’s pioneering work came to fruition in the early 1980s, after he founded Grid Systems, a company in Mountain View, Calif. As chief executive, he assembled an engineering and design team that included the noted British-born industrial designer William Moggridge.

The team produced a clamshell computer with an orange electroluminescent flat-panel display that was introduced as the Compass. It went to market in 1982. The Compass is now widely acknowledged to have been far ahead of its time.

“The Grid Compass was the first successful clamshell laptop computer,” said Marc Weber, a historian at the Computer History Museum in Mountain View.