As far as programming is concerned,
What is required to initialize a video card and access the video memory on it?
How does OpenGL do it?
Is it a driver?
You will not easily find information about this on the Internet, but I’d appreciate any pointers in the right direction.
The purpose of GL is not for accessing video memory, but to give rendering commands. On a PC running Windows, the commands go to opengl32.dll or to the driver, the driver does it job, finally commands are sent in batches to the GPU.
AMD has released some information about their hardware, to allow linux-developers to write their own drivers. Maybe you will find what you are looking for in those documents. Though i don’t know where exactly you will find them, google for it.
More than I ever wanted to know about GPUs