Sega Virtua Processor

The Sega Virtua Processor (short: SVP) is a DSP introduced by Sega in 1994 to expand the Sega Mega Drive's (Sega Genesis in North America) 3D capabilities.

The SVP was Sega's answer to Nintendo's Super FX processor used in some of their SNES cartridges.

Technical Details

The SVP is thought to be a Samsung SSP1601 16-bit Fixed Point DSP with Sega branding. For a long time it was assumed to be a SH-x DSP in the homebrew scene. The assumption was based on the fact that Sega has used SH-1 and SH-2 processors for their 32X and Saturn consoles.

The only usage of the SVP was in the Sega Mega Drive/Sega Genesis version of "Virtua Racing". Its main task was to calculate the polygonal graphics of the game. The main purpose of the SVP is to render polygons as 8x8 patterns, which the game program transfers to VRAM from the 128K RAM area using DMA. [http://code.google.com/p/genplus-gx/source/diff?r=31&format=side&path=/trunk/docs/gen-hw.txt Sega Genesis hardware notes] at [http://cgfm2.emuviews.com/ Charles MacDonald's Home Page] ] The SVP runs at 23 MHz and can calculate 300 to 500 polygons/frame at 15 frames per second with a maximum of 16 colours. It also has its own small heat sink because it gets warm during operation.

Implementations

At the time of release, the SVP was set to rise the cost of the "Virtua Racing" cartridges (the game cost £70 in the UK, and $100 in the U.S.), which can be seen as a major reason why the SVP was only used in "Virtua Racing". Sega of America started to develop the 32X expansion console around that time.

Due to a clash between memory addresses used by the 32X and the SVP, "Virtua Racing" is the only Mega Drive game which doesn't run with an attached 32X. A 32X version of the game called Virtua Racing Deluxe was released later in 1994, featuring more polygons per track and car, three cars and two more tracks. It has been theorized by many that an SVP adaptor (similar to the 32X) was in development prior to the 32X creation.

Emulation

An emulator called PicoDrive is capable of emulating the SVP, the source code is available. [http://notaz.gp2x.de/svp.php Proof of Concept SVP emulator for GP2x] at [http://notaz.gp2x.de/ Notaz's Homepage] ] .

An emulator for the Wii console called Genesis Plus GX is able to emulate the SVP, it uses the Twilight Hack to run in Wii mode. [http://gxdev.wordpress.com/2008/03/02/how-to-reach-the-limits/ Wii Genesis Emulator] at [http://gxdev.wordpress.com/ ekeeke's Dev Blog] ]

Also, an emulator called Regen, emulates the SVP.

References

External links

* [http://www.hacking-cult.org/?r/31 More information about the SVP]
* [http://www.sega-16.com/feature_page.php?id=37&title=Sega's%20SVP%20Chip:%20The%20Road%20not%20Taken? Sega's SVP Chip: The Road not Taken?]
* [http://www.sharemation.com/TascoDLX/SVP%20Reference%20Guide%202007.02.11.txt SVP Reference Guide (annotated)]
* [http://www.sharemation.com/TascoDLX/SVP%20Register%20Guide%202007.02.11.txt SVP Register Guide (annotated)]