Vector Sigma

Vector Sigma, as seen in the G1 Series

The exterior of the Vector Sigma chamber, as seen in the Japanese Headmasters series.

Vector Sigma itself in Headmasters, sporting a slightly different look than in the original series.

Vector Sigma is an ancient and incredibly powerful super computer which exists in certain G1 universes. Specifically, it appears in the G1 cartoon, and the series Beast Machines (where it also goes by the name "The Oracle"). It was also referenced by Shockwave in the Dreamwave "War and Peace" comic and figures into 3H's comic, Transformers Universe: Featuring the Wreckers.

When awakened, it often announces, "I am Vector Sigma. Before Cybertron was, I was."

Generation 1

In the G1 cartoon, Vector Sigma could easily be considered the equivalent of the god Primus. It is found deep underground on Cybertron and has the ability to bestow life upon Transformers.

Vector Sigma was introduced in the two part season two episode The Ket to Vector Sigma. In this episode, Megatron steals Vector Sigma's activation key from Alpha Trion and uses the computer to activate his recently built Stunticon Transformers. He then leaves Cybertron with the Key still in tow. In retaliation, Optimus constructs and uses Vector Sigma to envigorate the Aerialbots. Alpha Trion sacrifices his body in order to activate Vector Sigma long enough for these new Autobots to come to life.

Shortly thereafter, it is revealed that in addition to activating Vector Sigma, the key has the bizarre ability to turn any organic matter it came in contact with into lifeless metal. Megatron attempts to use this power to drain the Earth of all its natural energy, but his plans are thwarted and the key destroyed.

Vector Sigma, the Oracle, and Primus

The Oracle appears, on the outside, like a ball of "outer space".

Beast Machines features a computer very much like Vector Sigma called the Oracle. It is revealed near the end of season one that the Oracle is, indeed, the same thing as Vector Sigma. Or, at the least, that the Oracle is some sort of shell, wrapper, or interface to Vector Sigma.

The Wreckers comics from 3H are set contemporaneously to the Beast Machines cartoon, and further establish that the Oracle is a shell program constructed by the Quintessons to limit the potency of Vector Sigma. Occasionally, Vector Sigma is able to break through the Oracle and issue commands. At other times, the Oracle's messages are lies planted by the Quintessons or whoever else may have gained control of the shell program. (It is unclear how this is meant to fit in with the Oracle's messages to Primal within Beast Machines itself, as those messages seem to have all been true.)

The Quintesson Al-Badur describes Vector Sigma itself as "the ultimate physical embodiment" of Primus. This, along with the computer's life-granting abilities, allow a series of extrapolations to be made: Vector Sigma is a gateway of sorts to the Matrix, also known as the Allspark, which is the collection of all Transformer life energy or sparks. Sparks themselves are fragments of the essence of Primus. The Creation Matrix is a similar gateway to the Matrix, albeit without the built-in supercomputer.

From Teletraan I: The Transformers Wiki, a Wikia wiki.