PowerVR

PowerVR is a subsidiary of Imagination Technologies, a unique technology they developed for the display of 3D scenes and a series of Graphics card based on that technology which had a brief period of popularity during the 1990s and survive in mobile and embedded implementations. The 3D accelerators were not manufactured by PowerVR but were licensed to other companies such as NEC Corporation.

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 Technologies and NVIDIA expelled both companies from primary roles in the industry. Since 2002, many games no longer officially support the PowerVR.

=Implementations=

==The Sega Dreamcast==

The second generation PowerVR2 chip found a new lease of life in the Sega Dreamcast console until that stopped production in 2001. During the competition, PowerVR2 was licensed to NEC and it beat out the 3dfx Voodoo 2 offering to secure the Sega contract. Thanks to the performance of the PowerVR2, several Dreamcast games such as Quake 3 could rival their PC counterparts in quality and performance.

==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 was based upon the PowerVR4 which did include hardware Transform and lighting but it never came to fruitation.

==PowerVR MBX==

With the high end PC market secured by ATI and NVIDIA, PowerVR is now concentrating on the mobile 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 the Dell x50v PDA, Fujitsu FOMA901 mobile phone and Pepper Pad, with many other PDA/tablet PCs and mobile phones due soon.

= The 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 done until all polygon information has been collated - hence rendering is deferred.

For rendering 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 appear to 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 visible pixels 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.

PowerVR did not pioneer the concept of tile based rendering but is the only company to produce hardware based on it. Microsoft originally conceptualised the idea with their abandoned Talisman project. Gigapixel were a company that produced tile based IP for 3D graphics until they were bought by 3Dfx, who were subsequently bought by Nvidia. Nvidia has no official plans to pursue tile based rendering at current.

=PowerVR Chipsets=

Places PowerVR technology and its various iterations have been are:

== Series 1 ==

== Series 2 ==

== Series 3 (STMicro) ==

== Series 4 (STMicro) ==

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

== Series 5 ==

Naomi II arcades (set top boxes) - no details known.

== Mobile ==

PowerVR MBX (mobile version)

=References=

[http://www.pvrdev.com/ PowerVR Developer Relations]

= External Links =

[http://www.powervr.com www.powervr.com (homepage)] [http://www.pvrgenerations.co.uk www.pvrgenerations.co.uk (fansite)] [http://www.pvr-extremist.com www.pvr-extremist.com (fansite)]