Brain is the name given to a computer virus that was initially released on 19 January 1986, considered to be the first targetted at the IBM Personal Computer (IBM PC) and compatibles; it spread via infected floppy disks.^[1]

Brain was written by Amjad Farook Alvi, who with his brother Basit Farooq Alvi ran a computer shop in Lahore, Pakistan, initially focused on repairing Sinclair computers and then IBM PCs.^[2][3] According to an article in Time magazine, they also sold “brand-name computer programs”, such as Lotus 1-2-3 and WordStar, which at the time cost several hundred dollars in the United States, for as little as $1.50 each. But unknown to the purchasers, hidden in nearly every disk was what many consider to have been the world’s most sophisticated computer virus; every time an unsuspecting user lent the disk to a friend or colleague, it spread from computer to computer.^[2]

In an interview broadcast by the BBC World Service in 2026, Amjad claimed that he and his brother had for the first time included the code in a piece of medical software written for a doctor friend, who did not have the funds to pay for it. So Amjad developed the software on condition that it would not be shared. There was effectively no copyright law in Pakistan, and therefore no way to make a legally binding agreement, so instead Amjad included the virus in the code he delivered on a floppy disk, with the warning that the disk should never be copied.^[4]

Description

In the early days of personal computing, users were offered the choice of booting their computers from floppy disks, hard drives or even cassette recorders. The floppy disk in particular, in its innermost sector, contained machine code to be loaded into random-access memory (RAM) and then executed by the computer’s built-in firmware.

The Brain virus worked by replacing the boot sector of a floppy disk with a copy of the virus. The effects were relatively benign, as it only slowed down the floppy disk drive, and displayed a message asking for payment to innoculate the computer:^[5]

Boot sector viruses such as Brain disappeared when floppy discs went out of fashion.^[1]