Does anyone have a comprehensive explanation of how the graphics system works?

jj1984

Member
Hello,

OK, so I finished Intel's big manual, and, as I lamented in another recent post, there was no mention whatsoever of the graphics system.

I find this unusual as for many cheap models like my laptop the graphics system is actually a part of the CPU.

But, alas, no mention at all.

Does anyone know, or can anyone point me to a thorough explanation of how the graphics system works?

I know that either on a graphics card or in RAM there is a memory structure called a frame buffer.

The monitor pulls that data 60 times/second and sends it to the pixels.

The pixels in turn shine a certain frequency of light as a function of the voltage applied across them.

This is how 0's and 1's become colors.

No matter what you're doing: looking at your desktop, watching a video, writing a word document, etc. this is how images are placed on the screen.

But how do we get there?

What about all the abstraction layers above this bottom hardware layer?

Also, in what state is the graphics system in the pre-boot environment?

If I write my own bootable code on a USB or something and boot my own "OS" of sorts and don't jump into protected mode and just keep things in real mode, what kind of control do I have over the screen?

Would I be able to write to each pixel individually?

Thanks.
 

Cromewell

Administrator
Staff member
If you want a manual like the intel bible you are probably going to have to search the nvidia/ati archives (pretty sure anything from 3dfx is long gone). Intel may have a similar paper published for the workings of their GPUs, but I haven't ever tried to search it out. The normal OpenGL/DirectX pipeline is fine for me.

Also, in what state is the graphics system in the pre-boot environment?
Prior to boot the BIOS operates the video hardware in a generic mode (some form of xGA).

If I write my own bootable code on a USB or something and boot my own "OS" of sorts and don't jump into protected mode and just keep things in real mode, what kind of control do I have over the screen?
You can ask the BIOS to do it for you. Or you can interface with the hardware directly, which is a LOT faster. You'd be searching for VGA programming (or svga or wxga or .... you get the idea)
 
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