Brain affects the PC by replacing the boot sector of a floppy disk with a copy of the virus. The real boot sector is moved to another sector and marked as bad. Infected disks usually have five kilobytes of bad sectors. The [[Virus]] slows down the floppy disk drive and makes seven kilobytes of memory unavailable to DOS. Brain was written by *Amjad Farooq Alvi*, to protect their medical software from illegal copying, and it was supposed to target copyright infringement only. This program was originally used to track a heart monitoring program for the IBM PC, and people were distributing illicit copies of the disks. This tracking program was supposed to stop and track illegal copies of the disk, however the program also sometimes used the last five kilobytes on an Apple floppy, making additional saves to the disk by other programs impossible.