The Michelangelo virus is a computer virus first discovered on 3 February 1991 in Australia.[1] The virus was designed to infect DOS systems, but did not engage the operating system or make any OS calls. Michelangelo, like all boot sector viruses, operated at the BIOS level. Each year, the virus remained dormant until March 6, the birthday of Renaissance artist Michelangelo. There is no reference to the artist in the virus, and it is doubtful that the virus's developer(s) intended a connection between the virus and the artist. The name was chosen in researchers who noticed the coincidence of the activation date. The actual significance of the date to the author is unknown. Michelangelo is a variant of the already endemic Stoned virus.[citation needed] On March 6, if the PC is an AT or a PS/2, the virus overwrites the first one hundred sectors of the hard disk with nulls. The virus assumes a geometry of 256 cylinders, 4 heads, 17 sectors per track. Although all the user's data would still be on the hard disk, it would be irretrievable for the average user.[citation needed] On hard disks, the virus moves the original master boot record to cylinder 0, head 0, sector 7.