the release of the Super NES, companies began marketing backup devices such as the Super Wildcard, Super Pro Fighter Q, and Game Doctor. These devices create a backup of a cartridge, and can be used to play illicit ROM images or to copy games, violating copyright laws in many jurisdictions. The Japan-only Satellaview is a satellite modem attached to the Super Famicom's expansion port and connected to the St.GIGA satellite radio station from April 23, 1995, to June 30, 2000. Satellaview subscribers could download gaming news and specially designed games, which were frequently either remakes of or sequels to older Famicom games, and released in installments. In the United States, the relatively short-lived XBAND allowed users to connect to a network via a dial-up modem to compete against other players around the country. Nintendo attempted partnerships with Sony and then Philips, to develop CD-ROM-based peripheral prototypes for the console to compete with the Sega CD. Sony produced a Nintendo Play Station prototype which was canceled, diverting this inertia into its own PlayStation console. The Philips project was canceled without a prototype but Philips retained the contractual right to develop games based on Nintendo franchises, which it published for its CD-i multimedia console. Enhancement chips As part of the overall plan for the Super NES, rather than include an expensive CPU that would still become obsolete in a few years, the hardware designers made it easy to interface special coprocessor chips to the console, just like the MMC chips used for most NES games. This is most often characterized by 16 additional pins on the cartridge card edge. The Super FX is a RISC CPU designed to perform functions that the main CPU can not feasibly do. The chip is primarily used to create 3D game worlds made with polygons, texture mapping and light source shading. The chip can also be used to enhance 2D games. The Nintendo fixed-point digital signal processor (DSP) chip allowed for fast vector-based calculations, bitmap conversions, both 2D and 3D coordinate transformations, and other functions. Four revisions of the chip exist, each physically identical but with different microcode. The DSP-1 version, including the later 1A and 1B bug fix revisions, is used most often; the DSP-2, DSP-3, and DSP-4 are used in only one game each. Similar to the 5A22 CPU in the console, the SA-1 chip contains a 65C816 processor core clocked at 10 MHz,