Celsius is the codename for a GPU microarchitecture developed by Nvidia, and released in 1999 microarchitecture. It was named with reference to Anders Celsius and used with the GeForce 256 and GeForce 2 series.
While Celsius was not used as a marketing name at the time of the GeForce 256's launch in 1999, the public name was first used by the nouveau Linux driver, and much later on the Nvidia website.
The company's naming convention using famous scientists for its microarchitectures only became standard practice starting with the Tesla/Fermi generations.
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