How GPU's Work

kinetic · Dec 12, 2002, 06:35 PM

For those of you who haven't a clue how graphics processors work (like me!) read on.

Explained
How graphics processor chips work.
By Alan Zeichick
December 11, 2002

For more than 20 years, general-purpose microprocessors, like those manufactured by Advanced Micro Devices, IBM, and Intel, have been viewed as the workhorses of desktop and server computers. But graphics processor chips, which have seen innovative technical developments and outstanding performance, might capture the limelight.

Made by companies like ATI Technologies, Nvidia, and Silicon Integrated Systems, graphics processors enable the high-resolution, lifelike images seen on computer screens and video game consoles. Indeed, a graphics processing unit (GPU) uses specialized circuitry to generate dynamic three-dimensional images faster than central processing units. This frees CPUs to run routines for which they are better designed, like directing the action behind a game.

Let's say, for example, that a computer is running software that displays a 2D or 3D rendered image of an airplane flying over a mountain range. In the old days, before powerful GPUs, the software and the CPU would have the burden of identifying every picture element of the image--the texture of the plane, the sharpness of small details like engines, the reflection of sunlight, and the clouds it blocks as it moves. Today, the CPU can pass all the relevant details, like shapes, physical details, and positions of objects, directly to the GPU. And the GPU's special hardware knows what to do with that information.

First the GPU uses a geometry engine to calculate the geometry of the picture. It determines the proper position, rotation, and scale of each object in the picture, and splits each object into a large number of tiny triangles--which are easier to work with than curved or rounded objects--by applying mathematical routines.

Each triangle is then assigned coördinates and rendered in the completed geometry. The GPU assigns each pixel in the triangle the correct color, based on factors like shadow, tone, reflection, and texture.

Once a triangle has been translated, it is written to a special memory chip connected to the GPU. This chip, which semiconductor engineers call the frame buffer (or video memory), contains a complete version of the video scene (a frame) and holds it until it is time for that frame to be projected onto a computer monitor or TV screen.

If the image is meant to be displayed on a TV or monitor, as opposed to written to disk, each frame is written to a random-access memory digital-to-analog converter, or RAMDAC, which converts it to the analog format used by most TVs and computer monitors and then sends it to the display.

Computers are running increasingly more complex types of graphics, and users' appetites for ever-greater realism are not expected to abate. The speed with which a GPU chip can calculate the geometry, and the quality and detail of the rendering, is key to satisfying those users.

Alan Zeichick is principal technology analyst with Camden Associates and is editor in chief of BZ Media's SD Times.

Louie6666 · Dec 12, 2002, 07:04 PM

I really hope thats a cut 'N' paste, and you didn't have to type it, cheers M8 intresting read

digitalwanderer · Dec 12, 2002, 07:24 PM

It's the magic viddy-fairies that live inside your video card, everyone knows that! (Makes about as much sense as the real explanation to me.

)

DriveEuro · Dec 12, 2002, 08:12 PM

Sounds bueno to me, I am now .00000000013% smarter. HEHE

Ryoko · Dec 12, 2002, 08:18 PM

blah blah blah old news and insufficiently detailed...

kinetic · Dec 12, 2002, 08:42 PM

Quote:

Originally posted by Ryoko
blah blah blah old news and insufficiently detailed...

Well, I did say it was for the un-initiated, not techno geeks like yourself.

digitalwanderer · Dec 12, 2002, 08:50 PM

Quote:

Originally posted by kinetic
Well, I did say it was for the un-initiated, not techno geeks like yourself.

Oh, quit your whining! Didn't you just win a new CPU/mobo or something, and you're still bitching?

There is just no satisfying some people! (J/K!

)

Ryoko · Dec 12, 2002, 09:13 PM

Quote:

Originally posted by digitalwanderer
Oh, quit your whining! Didn't you just win a new CPU/mobo or something, and you're still bitching?

There is just no satisfying some people! (J/K! )

yah, well... yer complaining about his complaining so there

Ryoko · Dec 12, 2002, 09:14 PM

Quote:

Originally posted by kinetic
Well, I did say it was for the un-initiated, not techno geeks like yourself.

didn't see that part... guess intelligence really does take the place of common sense

Neo69 · Dec 25, 2002, 11:07 PM

well if you need a good, basic, sum-up about graphics card, for your mom or something *g* this does the job well

Dec 12, 2002, 06:35 PM	#1
kinetic DriverHeaven Senior Member Join Date: May 2002 Location: Manchester England Posts: 2,559 Rep Power: 0	How GPU's Work For those of you who haven't a clue how graphics processors work (like me!) read on. Explained How graphics processor chips work. By Alan Zeichick December 11, 2002 For more than 20 years, general-purpose microprocessors, like those manufactured by Advanced Micro Devices, IBM, and Intel, have been viewed as the workhorses of desktop and server computers. But graphics processor chips, which have seen innovative technical developments and outstanding performance, might capture the limelight. Made by companies like ATI Technologies, Nvidia, and Silicon Integrated Systems, graphics processors enable the high-resolution, lifelike images seen on computer screens and video game consoles. Indeed, a graphics processing unit (GPU) uses specialized circuitry to generate dynamic three-dimensional images faster than central processing units. This frees CPUs to run routines for which they are better designed, like directing the action behind a game. Let's say, for example, that a computer is running software that displays a 2D or 3D rendered image of an airplane flying over a mountain range. In the old days, before powerful GPUs, the software and the CPU would have the burden of identifying every picture element of the image--the texture of the plane, the sharpness of small details like engines, the reflection of sunlight, and the clouds it blocks as it moves. Today, the CPU can pass all the relevant details, like shapes, physical details, and positions of objects, directly to the GPU. And the GPU's special hardware knows what to do with that information. First the GPU uses a geometry engine to calculate the geometry of the picture. It determines the proper position, rotation, and scale of each object in the picture, and splits each object into a large number of tiny triangles--which are easier to work with than curved or rounded objects--by applying mathematical routines. Each triangle is then assigned coördinates and rendered in the completed geometry. The GPU assigns each pixel in the triangle the correct color, based on factors like shadow, tone, reflection, and texture. Once a triangle has been translated, it is written to a special memory chip connected to the GPU. This chip, which semiconductor engineers call the frame buffer (or video memory), contains a complete version of the video scene (a frame) and holds it until it is time for that frame to be projected onto a computer monitor or TV screen. If the image is meant to be displayed on a TV or monitor, as opposed to written to disk, each frame is written to a random-access memory digital-to-analog converter, or RAMDAC, which converts it to the analog format used by most TVs and computer monitors and then sends it to the display. Computers are running increasingly more complex types of graphics, and users' appetites for ever-greater realism are not expected to abate. The speed with which a GPU chip can calculate the geometry, and the quality and detail of the rendering, is key to satisfying those users. Alan Zeichick is principal technology analyst with Camden Associates and is editor in chief of BZ Media's SD Times.

Dec 12, 2002, 07:04 PM	#2
Louie6666 Just One Sick-Lizard Join Date: Jul 2002 Location: Bristol, UK Posts: 501 Rep Power: 0	I really hope thats a cut 'N' paste, and you didn't have to type it, cheers M8 intresting read __________________

Dec 12, 2002, 07:24 PM	#3
digitalwanderer Colour Commentator Join Date: May 2002 Location: Highland, IN USA Posts: 5,619 Rep Power: 0	WRONG! It's the magic viddy-fairies that live inside your video card, everyone knows that! (Makes about as much sense as the real explanation to me. ) __________________ WTF is up with the sigs?

Dec 12, 2002, 08:12 PM	#4
DriveEuro HardwareHeaven Extreme Member Join Date: Jul 2002 Location: Gurnee Illinois Posts: 4,677 Rep Power: 0	Sounds bueno to me, I am now .00000000013% smarter. HEHE __________________ [color=orange]ASUS P4P800 Deluxe [color=black]-[/color] 2.4C --> 3300mhz [color=black]-[/color] Mushkin PC3200 at 220 5-2-2-2 (cpu limited) [color=black]-[/color] BBAti 9800Pro at 430/375 [/color] [color=black]3[/color][color=gray]D[/color]M[color=black]a[/color][color=gray]r[/color]k[color=yellow]01[/color] [color=black]3[/color][color=gray]D[/color]M[color=black]a[/color][color=gray]r[/color]k[color=yellow]03[/color] 16001200 12801024

Dec 12, 2002, 08:18 PM	#5
Ryoko American Soldier Join Date: May 2002 Location: Williamsburg, VA Posts: 1,725 Rep Power: 0	blah blah blah old news and insufficiently detailed...

Dec 25, 2002, 11:07 PM	#10
Neo69 DriverHeaven Newbie Join Date: Dec 2002 Posts: 13 Rep Power: 0	well if you need a good, basic, sum-up about graphics card, for your mom or something g this does the job well