VANCOUVER, British Columbia

IN January 1986, Basit and Amjad Alvi, sibling programmers living near the main train station in Lahore, Pakistan, wrote a piece of code to safeguard the latest version of their heart-monitoring software from piracy. They called it Brain, and it was basically a wheel-clamp for PCs. Computers that ran their program, plus this new bit of code, would stop working after a year, though they cheerfully provided three telephone numbers, against the day. If you were a legitimate user, and could prove it, they’d unlock you.

But in the way of all emergent technologies, something entirely unintended happened. The Alvis’ wheel-clamp was soon copied by a certain stripe of computer hobbyist, who began to distribute it, concealed within various digital documents that people might be expected to want to open. Because almost all these booby-trapped files went out on floppy disks, the virus spread at a pre-Internet snail’s pace.

Still, it did wreak a certain amount of low-grade havoc, freezing computers across the world. The hobbyists did it because they could, or to proudly demonstrate that they could, or to see what would happen, or simply because they thought it was neat.

This proved hellishly embarrassing for the Alvi brothers, whose three telephone numbers were often inadvertently included in the files, and eventually they had to cut all three lines. There were far too many angry callers, mainly from the United States and Britain. In short, the road to our present universe teeming with viruses, worms and Trojan horses was paved, a quarter-century ago this month, with the Alvi brothers’ good intentions of securing their intellectual property.