What does Compute Unified Device Architecture mean?

so unified device architecture supposes that the hardware architecture for general purpose and graphics computing was unified?
but what does compute mean?

Prior to the existence of CUDA, going back to approximately the year 2000, NVIDIA had a Unified Device Architecture. I won’t be able to go into much detail, but the Unified Device Architecture had ramifications for how new GPU architectures were developed, and had implications for driver development as well. It was considered to be a good thing, at least by NVIDIA. You could think of it as kind of a standardization of a way to “talk to the GPU” at a low level. Prior to UDA, each GPU architecture was potentially a clean slate, and could involve a whole new interface to the GPU at a low level, and therefore potentially a complete re-write of the GPU driver. With some careful searching you can find some write-ups of “UDA” when it was still “new”, such as here.

When an ability to use a GPU for general purpose computation programmed via C/C++ was added to the NVIDIA GPU architecture in about the 2007 timeframe, there was also a standardized method created to define at a low level how the GPU would process general purpose C/C++ code. This ability to process general purpose code was referred to as “compute” (such as in “compute capability”), and the new architecture was called “CUDA”, for compute unified device architecture. Not unlike the UDA transition, CUDA brought with it some kinds of forward and backward compatibility, because of the standardized approach to indicating how to use or program or “talk to the GPU” at a low level. There was a conscious intention made not to have to rewrite everything with each new generation/architecture.

I personally wouldn’t spend a lot of time trying to extract a precise meaning from the CUDA moniker. I view most of this as history, not adherence to a plan or specification. Today, CUDA is a heavily overloaded term, referring to many things beyond this description that I have given here.

Today, it’s largely a marketing term; a brand, if you will.

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