Magneto-optical disk

The MO disk ("Magneto-optical") is a form of information disk used by Umbrella. The disk-type, which uses lasers and electromagnets to read its recording layer, is common in Japan, though has fallen into disuse in western nations. The company continued to use them in their laboratories world-wide as far as 1998, thirteen years after the disk's introduction onto the market.

Resident Evil 0
The label reads "Security System ver. 1.02". It's probably used to activate some sort of security system.

In the Umbrella Research Center, an MO disk is needed to operate a terminal that gives a code to open certain doors of the facility.

Resident Evil 1/Remake


It appears to be a disk for rebooting a system of some sort.

In the Arklay Laboratory, access to the prison cell was denied without the planting of all three MO disks into a reader. Each was kept in level B3 - the morgue; fuel storage lab and power rooms. To get the best possible ending, all three disks were required.

Resident Evil 2


The label says "For Cargo Room Verification".

In Dr. William Birkin's laboratory, an MO disk was required to activate the elevator in the B5F Cargo Room to allow entry to the platform on level B8F.

Resident Evil 3
An MO disk was also required at the P-12A Incinerator Facility to gain access to the incinerator room.

Resident Evil Outbreak: File #2
Two MO disks were recovered by outbreak survivors in an Umbrella facility: the first was used to take up information and program into the Tyrant T-0400TP before its activation, while the second contained information on people experimented on with the t-virus.