A motherboard tattoo is a unique code that can be written in the basic input/output system (BIOS) of a computer to ensure that system restore or diagnostic compact discs (CDs) will work only on the machine or line of machines with which the CDs are sold. The tattoo process ensures that recovery or diagnostic CDs cannot be illegally used with computers other than those for which they are intended to be used.
A tattoo consists of an erasable programmable read-only memory (EPROM) chip that contains information about the machine, such as the serial number and operating system data. This chip is unique to each machine. If the motherboard, or certain components on it, are replaced, the EPROM chip must be reprogrammed. The same is true if the original recovery or diagnostic CDs are lost. The technical support department of the computer vendor, or the technician who performed modifications or repairs, should be contacted for details about the reprogramming (re-tattooing) process.