Clyde Rodriguez spent his childhood toiling in fields picking grapes and garlic under a scorching summer sun.

The exhaustion of those days ended thanks to his dreams of becoming a software engineer. Rodriguez, now 49, went on to work for Bill Gates and Steve Jobs, and his love of computers has taken him around the world.

Recently, he returned home to encourage the next generation at Madera High School’s graduation. “All of us are descendants of immigrants who, like others over the course of 300 years, have become integral threads of this country’s fabric,” he said. “Consider that eight of the signers of the Declaration of Independence were themselves immigrants.”

Some of Rodriguez’s biggest achievements: He led a team that built a new Windows operating system that could consume vast amounts of information, and he later founded a team that developed cloud technology. He’s also advised the U.N. on the use of technology for international development.

“It all feels like a dream at times,” he said. “Surely, this is someone else’s life. Surely, it’s not that of a farm kid whose earliest memories are those of living in a tin-roofed house in Tijuana without running water or electricity, where our family gathered around burning tires my father would gather for heat from a nearby drying riverbed — our noses covered in soot. But it is. It is my story.”

He said he found his purpose when he was about 10, working alongside his mother. They were wrapping grapevines when a wire came loose and lashed his mother, leaving a “thick, burning, bright red line” across her face. Her eyes filled with tears, but she said she was OK.

“One day I’m going to take you out of this place,” he vowed.

After graduating from Madera High in 1986, Rodriguez was admitted into the competitive electrical engineering and computer science program at the University of California, Berkeley. But during his second year, he withdrew from his dream school to help his father, who had been stabbed 20 times, recover.

When he was ready to return to UC Berkeley, he was denied readmission. Undaunted, he enrolled in the extension program, taking the same classes as full-time students, then petitioned the dean for readmission. “Each time he denied my request, finally telling me I did not belong there and to stop wasting his time and, he claimed, mine.”

It only strengthened his resolve. After a third semester in the extension program, Rodriguez returned to the dean — this time armed with letters of recommendation from professors. The university finally agreed to readmit him. Six months later, he graduated from UC Berkeley, delivering his school’s commencement speech.

Five years later, he handed his mother a note from the bank that showed he had paid off their mortgage. “Their 40 years of working in the fields had at last come to an end, and a promise made by a 10-year-old boy in the middle of a vineyard had been completed.”

Rodriguez, who works for a financial tech company, told the graduates: “Be bold, be fearless, fight comfort, write your next chapter. The pen is yours. Let no one take it from you.”