Sega Virtua Processor
This article relies largely or entirely on a single source. (July 2012)
|Type||Digital signal processor|
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 Mega Drive/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 tiles, which the game program transfers to VRAM from the 128K RAM area using DMA. The SVP runs at 23 MHz and can calculate 300 to 500 polygons/frame at 15 frames per second (up to 6,500 polygons per second) with a maximum of 16 colors. It also has its own small heat sink because it gets warm during operation.
At the time of release, the SVP was set to raise the cost of the Virtua Racing cartridges (the game cost $100 in the U.S. and £70 in the UK), which can be seen as a major reason why the SVP was only used in Virtua Racing. Sega and 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/Genesis 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[weasel words] that an SVP adapter (similar to the 32X) was in development prior to the 32X creation.
An emulator called PicoDrive was the first emulator capable of emulating the SVP; the source code is available and has subsequently been used in most emulators that support the SVP.
An emulator for the Wii console called Genesis Plus GX is able to emulate the SVP. Also, the Genesis emulator Regen emulates the SVP. As of version 3.6, the Kega Fusion Genesis/32x/CD emulator supports SVP emulation. The emulator MD.emu, a Genesis & Master System emulator for Android, also emulates the SVP.
The Retrogen Portable (a released Sega Mega Drive/Genesis) is compatible with the SVP.