The TARDIS log was a record of all of the trips taken by a TARDIS. (PROSE: The TARDIS Log [+]Loading...["The TARDIS Log (feature)"])
The log was automatically recorded on tape. The First Doctor knew of the log but had never felt any desire to examine it. (PROSE: Peril in Mechanistria [+]Loading...["Peril in Mechanistria (short story)"])
Jo Grant dictated to the TARDIS log in the Doctor's TARDIS after he was shot by the Master. It was later destroyed after the Doctor used it to disable a Dalek. (TV: Planet of the Daleks [+]Loading...["Planet of the Daleks (TV story)"])