Data Chip

From TARDIS Index File, the free Doctor Who reference.

A Data Chip is a small device seen on the collar of the suits used by the expedition the Doctor met in The Library. It is unknown what else the chip may be used for, but the team use it to communicate with one another.

When a Data Chip wearer dies or is killed, it is possible for a digital impression of their consciousness to be left in the chip for a short time. This has become known as Data Ghosting.

A Data Ghost frequently only 'survives' in this state for a short time due to the speed of the breakdown of the stored information, although one of the team claims that a relative of theirs lasted over a day in this state. (DW: Silence in the Library/ Forest of the Dead)