PowerVR

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PowerVR is a division of Imagination Technologies (formerly VideoLogic) and is also their brand of 3D accelerators which is the most popular choice for portable 3D devices, but is no longer available in desktop PCs. However as of July 2006 they are preparing to reintroduce desktop and portable PowerVR cores. Their earlier 3D accelerators were not manufactured by PowerVR, but instead the IP was licensed to other companies such as NEC.

The primary competitor to the PowerVR set of 3D chips in the late 1990s was the Voodoo series from 3dfx which would eventually become the market leader, before serious competition by ATI and NVIDIA expelled both companies from primary roles in the PC industry. Since 2002, many PC games no longer officially support the PowerVR.

1 Implementations
2 Technology
3 PowerVR chipsets
4 References
5 External links

[edit] Implementations

[edit] Sega Dreamcast

The second generation PowerVR2 chip found a new lease of life in the Sega Dreamcast console between 1998 and 2001. As part of an internal competition at Sega to design the successor the Saturn, the PowerVR2 was licensed to NEC and was chosen ahead of a rival design based on the 3dfx Voodoo 2. Thanks to the performance of the PowerVR2, several Dreamcast games such as Quake III Arena could rival their PC counterparts in quality and performance.

[edit] KYRO and KYRO II

In 2001, STMicroelectronics adopted the third generation PowerVR3 for their STG4000 "KYRO" and "KYRO II" chips. The STM PowerVR3 KYRO II, released in 2001, was able to rival the costlier ATI Radeon DDR and NVIDIA GeForce 2 GTS in benchmarks of the time, despite not having hardware transform and lighting. Unfortunately, as games were optimised for hardware transform and lighting, the KYRO II lost its performance advantage and is not supported by most modern games.

STM's STG5000 chip (right) was based upon the PowerVR4, which did include hardware T&L but it never came to commercial fruition.

[edit] PowerVR MBX

With the high end PC market secured by ATI and NVIDIA, PowerVR is now concentrating on the portable market with its latest design, the low power PowerVR MBX which has become the de facto standard for mobile 3D, having been licensed by six of the top ten semiconductor manufacturers including Intel, Texas Instruments, Samsung, Philips, Freescale, Renesas, and Sunplus.

Products that use the MBX include:

Renesas SH7770 (SH-Navi I) -- MBX + VGP + FPU + SH-4, Renesas unidentified -- MBX + SuperH

Mitsubishi HDD Navi H9000
Mitsubishi HDD Navi H9700
Pioneer Carrozzeria HDD CyberNavi AVIC-ZH900MD
Pioneer Carrozzeria HDD Cybernavi AVIC-VH009
Alpine Car Information Systems
Clarion MAX960

Renesas SH73180 (SH-Mobile3), Renesas SH73230 (SH-Mobile3A), Renesas SH73182 (SH-Mobile3+), Renesas SH73450 (SH-Mobile3A+) -- MBX Lite + VGP Lite + SH-4

Fujitsu F901iC
Mitsubishi D901i
Mitsubishi D901iS
Fujitsu F902i
Mitsubishi D902i
SK Teletech (SKY) IM-8300
Pantech PN-8300
Helio Hero
Motorola MS550
Mitsubishi D851iWM (MUSIC PORTER X)
Fujitsu F702iD
Mitsubishi D702i
Fujitsu F902iS
Mitsubishi D902iS

Renesas SH3707 -- MBX + VGP + FPU + SH-4

Sega Sammy Aurora

Renesas SH-Mobile G1 -- MBX Lite + VGP Lite + SH-4

Fujitsu F882iES
Fujitsu F903i
Fujitsu F903iX HIGH-SPEED
Mitsubishi D903i
Mitsubishi D903iTV

Renesas SH-Mobile G2 -- MBX Lite + VGP Lite + SH-4

Intel 2700G (Marathon) -- MBX Lite (as a companion to the Intel XScale processor PXA27x)

Compulab CM-F82 (PowerPC Module)
Dell Axim X50v
Dell Axim X51v
Pepper Pad
Advance Tech M.A.G.I.C.
Dresser Wayne iX Fuel Dispensers

Texas Instruments OMAP2420 -- MBX + VGP + FPU + ARM11

NEC N902i
Panasonic P902i
Sharp SH902i
Sony Ericsson SO902i
Nokia N93
Panasonic P702i
Sharp SH702iD
Sharp SH702iS
NEC N902iS
NEC N902iX HIGH-SPEED
Panasonic P902iS
Sharp SH902iS
Sharp DOLCE SL (SH902iSL)
Sony Ericsson SO902iWP+
Nokia N95

Texas Instruments OMAP2430 -- MBX Lite + VGP Lite + FPU + ARM11

NEC N903i
Panasonic P903i
Panasonic P903iX HIGH-SPEED
Sharp SH903i

Texas Instruments OMAPV2230 -- MBX Lite + VGP Lite + FPU + ARM11

Texas Instruments OMAP3430 -- MBX Lite + VGP Lite + ARM Cortex-A8

Philips Nexperia PNX4008 -- MBX Lite + ARM9

Sony Ericsson P990
Sony Ericsson M600
Sony Ericsson W950i
Sony Ericsson M608c
Sony Ericsson W958c

Freescale i.MX31 -- MBX Lite + FPU + ARM11

Samsung S3C2460 -- MBX Lite + FPU + ARM9

[edit] Technology

The PowerVR chipset uses a unique approach to rendering a 3D scene, known as Tile Based Deferred Rendering (often abbreviated as TBDR). As the polygon generating program feeds triangles to the PowerVR driver it stores them in memory in triangle strip format. Unlike other architectures, polygon rendering is not performed until all polygon information has been collated for the current frame – hence rendering is deferred.

In order to render, the display is split into rectangular sections in a grid pattern. Each section is known as a tile. With each tile is associated a list of the triangles that visibly overlap that tile. Each tile is rendered in turn to produce the final image.

Tiles are rendered using a process similar to ray tracing. Rays are cast onto the triangles associated with the tile and a pixel is rendered from the triangle closest to the camera. The PowerVR hardware calculates the depths associated with each polygon for one tile row in 1 cycle.

The advantage of this method is that, unlike with a more traditional z buffered rendering pipeline, work is never done determining what a polygon looks like in an area where it is obscured by other geometry. It also allows for correct rendering of partially transparent polygons independent of the order in which they are processed by the polygon producing application. However, this capability was only implemented in Series 1 and 2. It has been removed since for lack of API support and cost reasons. More importantly, as the rendering is circumscribed to a tile at a time, the whole tile can be in fast onchip memory, which is flushed to video memory before passing on to render the next tile. Note that, under normal circumstances, each tile only needs to be visited once per frame.

PowerVR is not the only pioneer of tile based deferred rendering, but the only one to successfully bring a TBDR solution to market. Microsoft originally conceptualised the idea with their abandoned "Talisman" project. Gigapixel, a company that developed IP for tile based deferred 3D graphics, were bought by 3Dfx, who were subsequently bought by Nvidia. Nvidia has no official plans to pursue tile based rendering at present.

Intel uses a similar concept in their integrated graphics solutions. However, their method, coined Zone Rendering, does not perform full hidden surface removal (HSR) and deferred texturing, therefore wasting fillrate and texture bandwidth on pixels that are not visible in the final image.

Recent advances in hierarchical z buffering have effectively incorporated ideas previously only used in deferred rendering, including the idea of being able to split a scene into tiles and of potentially being able to accept or reject tile sized pieces of polygon.

[edit] PowerVR chipsets

Places where PowerVR technology and its various iterations have been used are:

[edit] Series 1

Product	Type	Chip Name	Clock Rate
Apocalypse 3d/3dx	3D PC add-in board	PCX-1 and PCX-2	66 MHz
Matrox M3d	3D PC add-in board	PCX-1 and PCX-2	66 MHz

[edit] Series 2

Product	Type	Chip Name	Clock Rate
Sega Dreamcast	console	CLX2	100 MHz
Neon250	2D/3D PC add-in board	PowerVR 250PC	125 MHz
Naomi Arcades	set top boxes	CLX2	100 MHz
Naomi2 Arcades	set top boxes	2 CLX2s + ELAN	100 MHz

[edit] Series 3 (STMicro)

Product	Type	Chip Name	Clock Rate
KYRO	2D/3D PC add-in board	STG4000	115 MHz
KYRO II	2D/3D PC add-in board	STG4500	175 MHz
KYRO IISE	2D/3D PC add-in board	STG4800	200 MHz

[edit] Series 4 (STMicro)

KYRO 3 (2D/3D AIB) product shelved due to STMicro selling graphics division.

[edit] Series 5

Earlier Version (PC/arcade) shelved due to a lack of partner for the PC market and never being employed by licensee Sega Sammy for their arcade system.

SGX (next generation fully programmable universal scalable shader architecture):

exceeding requirements of OpenGL 2.0 and DirectX9 Shader Model 3.
licensed to Intel, Renesas,NEC and TI for OMAP 3
3 variants announced for the handheld mobile market: SGX510, SGX520, SGX530
Company presentation shows Thalia-L (consumer/automotive), Muse (portable computing), and Athena (desktop computing) cores in the SGX roadmap