This is the Artronic computer
network that handles all the systems aboard a
TARDIS.
The systems
connected to it include
the Navigation Systems, Guidance Systems, Drive Systems,
Defense Systems, the Life Support Systems,
and even the Emergency Transceiver.
With the exception of the Protyon
Unit, all of these systems are composed of exitonic
(a.k.a. Artronic) Circuitry and connected with fine grey,
hair-like interfaces. Lights move up and down these
hairs
searching for
faults.
Older Artron
Mainframes (like those on a Type 40) use Old High
Gallifreyan for their programming code.
Reliability is ensured by having the
Fault Locator operate independently of the
Mainframe.
Security is
ensured by requiring Command Codes to make major changes
to the programming.