the machine read the boot sector program, which normally loads the operating system, but ran the infected program instead. Once infected, the boot virus replicated itself onto all subsequent ...

That particular partition's boot sector is used to start the operating ... happen for various reasons—maybe a hijacking by an MBR virus, or corruption thanks to a physically damaged hard drive.

Aimed at the IBM PC, the Brain virus only slowed down the floppy disk drive and did no other damage. By replacing the boot sector in the floppy disk, a message would display claiming infection and ...