On Wednesday, Apple co-founder Steve Wozniak was hospitalized in Mexico City, according to organizers of the World Business Forum (WBF).

A source said Wozniak, 73, was taken to the hospital at 3 p.m. local time after fainting minutes before taking part in the event.

Wozniak was the tech genius behind the early Apple computers who helped start and grow the company with Steve Jobs.

Wozniak is known in Silicon Valley circles as “Woz” for designing the Apple I and Apple II computers, which revolutionized personal computing and made Apple a market leader.

In addition to being the technical engineer behind these systems, Wozniak served as the visionary and marketing expert behind them. Jobs and Steve Wozniak founded Apple in Jobs’ California garage in 1976, which is now the world’s most valuable company.