Graphics Processing Unit: Difference between revisions

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{{tropeUseful Notes}}
[[File:Nvidia@12nm@Turing@TU104@GeForce RTX 2080@S TAIWAN 1841A1 PKYN44.000 TU104-400-A1 DSC06154-DSC06272 - ZS-retouched (50914918427).jpg|thumb|Massive graphical performance. One tiny chip.]]
A GPU is the common term for a piece of a computer/console's hardware that is dedicated to drawing things. IE: graphics. The term "GPU" was coined by nVidia upon the launch of their GeForce line of hardware. This was generally a marketing stunt, though the GeForce did have some fairly advanced processing features in it. However, the term GPU has become the accepted shorthand for ''any'' graphics processing chip, even pre-GeForce ones.
 
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Both consoles and regular computers have had various kinds of GPUs. They had two divergent kinds of 2D GPUs, but they converged with the advent of 3D rendering.
 
=== Console 2D GPU ===
 
This kind of GPU, pioneered by the TMS 9918/9928 (see below) and popularized by the [[NES]], [[Sega Master System]] and [[Sega Genesis]], forces a particular kind of look onto the games that use them. You know this look: everything is composed of a series of images, tiles, that are used in various configurations to build the world.
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In this GPU, the tilemaps and the sprites are all built up into the final image by the GPU hardware itself. This drastically reduces the amount of processing power needed -- all the CPU needs to do is upload new parts of the tilemaps as the user scrolls around, adjust the scroll position of the tilemaps, and say where the sprites go.
 
=== Computer 2D GPU ===
 
Computers had different needs. Computer 2D rendering was driven by the needs of applications more so than games. Therefore, rendering needed to be fairly generic. Such hardware had a framebuffer, an image that represents what the user sees. And the hardware had [[Video RAM|video memory]] to store extra images that the user could use.
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Before the rise of Windows in the mid-1990s, most PC games couldn't take advantage of newer graphics cards with hardware blitting support; the CPU had to do all the work, and this made both a fast CPU and a fast path to the video RAM essential. PCs with local-bus video and 80486 processors were a must for games like ''[[Doom]]'' and ''[[Heretic]]''; playing them on an old 386 with ISA video was possible, but wouldn't be very fun.
 
=== Basic 3D GPU ===
 
The basic 3D-based GPU is much more complicated. It isn't as limiting as the NES-style 2D GPU.
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The early forms of this GPU were just triangle/texture renderers. The CPU had to position each triangle properly each frame. Later forms, like the first GeForce chip, incorporated triangle transform and lighting into the hardware. This allowed the CPU to say, "here's a bunch of triangles; render them," and then go do something else while they were rendered.
 
=== Modern 3D GPU ===
 
Around the time of the GeForce 3 GPU, something happened in GPU design.
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In the early days, "fairly arbitrary computations" was quite limited. Nowadays, not so much. These GPU programs, called ''shaders'', commonly do things like video decompression and other sundry activities. Modern GPUs can become something called the General Purpose GPU, which people have taken advantage of massive calculation performance of the GPU to do work that would take a CPU much longer to do.
 
=== Difference between GPU and CPU ===
GPUs and CPUs are built around some of the same general components, but they're put together in very different ways. A chip only has a limited amount of space to put circuits on, and GPUs and CPUs use the available space in different ways. The differences can be briefly summarized as follows:
 
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In the end, CPUs can execute a wide variety of programs at acceptable speed. GPUs can execute some special types of programs far faster than a CPU, but anything else it will execute much slower, if it can execute it at all.
 
=== The Future ===
 
GPUs today can execute a lot of programs that formerly only CPUs could, but with radically different performance characteristics. A typical home GPU can run hundreds of threads at once, while a typical mid-range home CPU can run two to4-16 fourthreads. On the other hand, each GPU thread progresses far more slowly than a CPU thread. Thus if you have thousands of almost identical tasks you need to run at once, like many pixels in a graphical scene or many objects in a game with physics, a GPU might be able to do work a hundred times faster than a CPU. But if you only have a few things to do and they have to happen in sequence, a CPU-style architecture will give vastly better performance. As general-purpose GPU programming progresses, GPUs might get used for more and more things until they're nearly as indispensable as CPUs. (OrIndeed, in some tasks a strong GPU is often required: From the late 2010s on, more and more consumer devices include powerful GPUs for things other than gaming, often related to maybemachine notlearning.)
 
=== Some notable GPUs over the years: ===
 
 
=== 1970s ===
'''Motorola 6845''' (1977)
 
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The first programmable home-computer GPU. ANTIC was ahead of its time; it was a full microprocessor with its own instruction set and direct access to system memory, much like the blitter in the [[Amiga]] 6 years later (which, not coincidentally, was designed by the same person). By tweaking its "display list" or instruction queue, some very wild special effects were possible, including smooth animation and 3D effects. CTIA and GTIA provided up to 128 or 256 colors, respectively, a huge number for the time.
 
=== 1980s ===
'''IBM Monochrome Display Adapter''' and '''Color Graphics Adapter''' (1981)
 
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=== 1990s ===
'''S3 86C911''' (1991)
 
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=== 2000s ===
'''3dfx Voodoo5''' (2000)
 
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In 2008, Intel announced they would try their hands in the dedicated graphics market once more with a radical approach. Traditionally lighting is actually estimated using shading techniques done on each pixel. Intel's approach was to use [[wikipedia:Ray tracing (graphics)|ray tracing]], which at the time was a hugely computationally expensive operation. Intel's design however was to use the Pentium architecture, but scale it down using modern integrated chip sizes, modify it for graphic related instructions. A special version of ''[[Enemy Territory: Quake Wars|Enemy Territory Quake Wars]]'' was used to demonstrate it. It was axed in late 2009.
 
nVidia tried their hands on "real time" ray tracing with the GeForce GTX 480 using a proprietary API. However nVidia's attempts would not see adoption until 2018 with the release of the GeForce 20 series, introducing RTX hardware accelerated ray tracing.
 
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[[Category:How Video Game Specs Work]]
[[Category:Graphics Processing Unit]]
[[Category:Pages with working Wikipedia tabs]]