Adam Osborne, 64, a technical writer, business executive and computer pioneer whose Silicon Valley achievements included the introduction of the Osborne 1, the first portable personal computer, died March 18 at his home in Kodiakanal, India.

Dr. Osborne had an organic brain syndrome and died following a series of strokes.

He introduced his computer in June 1981 at the West Coast Computer Fair. The computer, which retailed at $1,795, weighed 24 pounds and was about the size of a sewing machine. Dr. Osborne designed the machine to be light enough to carry as luggage and compact enough to fit under a commercial airline seat.

Dr. Osborne trumpeted his computer as "adequate," maintaining that it provided "90 percent of what most people need."

According to the electronics industry publication EE Times, the machine was based on the Zilog Z80 processor with 64 kilobytes of random-access memory, two 5.25-inch internal floppy drives, a five-inch monitor and no hard disk.

The computer came bundled with nearly $1,800 worth of software, including Microsoft Basic, the SuperCalc spreadsheet and the WordStar word processing program.

Osborne Computer Corp. of Hayward, Calif., rocketed to great heights and fell to the ground in a way that mirrored later Silicon Valley ventures.

The company took orders for 8,000 computers in 1981 and 110,000 in 1982. It had sales of $5.8 million in 1981 and $68.8 million in 1982.

It declared bankruptcy in 1983, with critics claiming that the company fell victim to Dr. Osborne's enthusiasm for the personal computer.

He trumpeted a next-generation computer, the Vixen, that would be much advanced to the Osborne I. The new computer proved to be not in the immediate offing, and sales of the Osborne I ground to a halt as buyers waited for the promised computer that never arrived.

A company's announcement of plans for a new product that resulted in a plummeting of sales in the old product is now referred to as the "Osborne Effect."

Dr. Osborne, who later allowed that his announcement of the new machine was "a big mistake," told his side of the story in the 1984 book "Hypergrowth." He was quoted as maintaining that he had been "raped" by "three-piece, pinstripe-suited vultures."

Dr. Osborne was born to British parents in Bangkok and grew up in India and Britain. A 1968 chemical engineering graduate of Britain's University of Birmingham, he received a doctorate in chemical engineering from the University of Delaware in 1968. It was while studying at Delaware that he learned to program a computer.

After completing his studies, he became a chemical engineer with Shell Oil in California, where he worked on computer models of chemical actions.

In 1974, he started Osborne and Associates, a company that wrote and published computer manuals, more than 40 of them in the following five years.

Later in the 1970s, he wrote "An Introduction to Microcomputers," a book that sold 300,000 copies. He sold his publishing concern to McGraw-Hill publishing in 1979. He also wrote a column for Interface Age magazine.

In 1984, he founded Paperback Software, a venture to publish software programs. The company failed after its spreadsheet program was found to infringe on the Lotus 1-2-3 system.

In 1992, Dr. Osborne started his last venture, Noetics Software, to explore such cutting-edge topics as neural networks and their application to computer programming. Later in 1992, he retired to India.

His marriages to Cynthia Geddes and Barbara Zelnick ended in divorce.

Survivors include three children.