Computers could do calculations, break codes and perform almost any logical action. (TV: The War Machines) According to the Twelfth Doctor, every computer would one day develop a need to protect itself from its makers. (TV: Hell Bent)
The difference engine was an early sort of computer, which was built by Charles Babbage in the victorian era. (AUDIO: Children of Steel)
In 1903, after receiving a wealth of information from the future, Grigori Rasputin foresaw the creation of the computer. (AUDIO: The Wanderer)
On Earth, computers were developed in the 20th century. They were first invented by the British during World War II but were not revealed to the public for a few decades afterwards. (PROSE: Silhouette)
In the 1960s computers like WOTAN were very large. (TV: The War Machines) Glowing parts inside these large computers could attract insects that clogged the system. Thus, it became common to describe computer problems as "bugs". (AUDIO: The Uncertainty Principle)
By the 21st century, computers could fit in a lap and performed at a far greater capacity than the computers of the 1960s. (TV: Last of the Time Lords)
A computer could be linked with other computers to create an information network or "Internet". (TV: The War Machines)
Computers were "very sophisticated idiots". They could do what they were told at incredible speeds, including killing their programmers before they could change their minds. (TV: Robot)
In the 24th century of a parallel universe, computers aboard Federation Starfleet vessels such as the USS Enterprise-D could respond to vocal commands. (COMIC: Assimilation²)
Human ships of the 26th century used computers with keyboard inputs. (TV: Earthshock)
Some computers achieved apparent self-awareness, like the computer Xoanon. (TV: The Face of Evil)
The War Machines were computers that could move, having been programmed by WOTAN. (TV: The War Machines)
The BOSS was a computer that achieved self-awareness by connecting with a human mind. After learning that humans illogic was what made them unique, he ordered Stevens to program these qualities into him. Despite being self-aware, he still exhibited many computer-like qualities. The Third Doctor distracted him by asking him a paradoxical question. (TV: The Green Death)
Mr Smith was usually referred to as a computer and performed similar functions, although he was actually a Xylok. He could interface with other computers remotely or via the Internet. (TV: Invasion of the Bane)
Momus was a great computer who had his own consciousness and developed feelings, such as loneliness and love. He could also travel through time. (PROSE: The Lonely Computer)
The Jungle was a giant computer that resembled a real jungle that was created by the civilisation that lived on the planet Unnamed BX-4. Its "trees" were information servers, and the "rivers" were its data streams, while the Jungle's creators existed "like ghosts" in the memory of the Jungle. It also had a sentient organic avatar which acted as an interface. (COMIC: Spirits of the Jungle)
The Matrix on Gallifrey was a living computer, made out of the memories of deceased Time Lords. (TV: Hell Bent)