December 21, 2001

Sharp Linux PDA promotes use of proprietary SD card, but more open MMC works just fine

Author: JT Smith

- by Tina Gasperson
Sharp's first Linux handheld, the Zaurus, has a proprietary, closed Secure Digital (SD) memory card expansion slot. Many people do not know the slot will also work with the MultimediaCard (MMC), a different kind of expansion card which is similar in power and potential, but much more open; in fact, it's a viable alternative for Linux developers who don't like the restrictions of the SD card. Why doesn't Sharp mention that MMCs are interchangeable with the SD cards in any of its Zaurus product literature?Linux people everywhere have hailed the advent of Sharp's Zaurus SL5000D handheld. It runs on Lineo's Embedix distribution and uses the Qt Palmtop Environment and Personal Java. Interested programmers can sign up at Sharp's developer site, order one of these cool PDAs for $399 USD, and get started creating applications to run on it.

MMCs fit into SD card slots and are readable in the same way. Sharp's decision not to include this information in advertisements for the Zaurus could hurt its chances of attracting a large community of developers. For cost reasons and on principle, Linux developers should know the MMC is a less restrictive alternative to the SD card, although the SD card has made some advancements in I/O and speed that some critics say the MMC is not currently capable of reaching.

Of course, because it's a Linux distribution, the source code for the Embedix OS on the Zaurus is freely available for download from Sharp -- except for the Proxim Open Air driver, the 802.11b wireless LAN driver, and the SD card driver. There is at least one alternative for the Proxim driver, and there are many alternatives for the 802.11b protocol -- but just try to find a driver of any kind for the SD Card.

If you do, it won't be a legal copy of one. That's because of the Secure Digital Card Association (SDCA). Member companies who want access to the specs for the SD card have to sign a strict non-disclosure agreement with SDCA and pay steep licensing fees. The companies are not allowed to share any SD technology, even if they've developed it themselves, with anyone who is not also a member company. Companies with access to the specs are not even permitted to make a photocopy; they must download separate, registered copies from the password-protected SDCA Web site.

The SD card was developed by Panasonic, SanDisk, and Toshiba specifically to produce a "memory card capable of providing a high level of copy protection for music, movies and other artistic and commercial content," according to an August 1999 press release announcing the creation of the SDCA.

The content copy protection feature is an option in the driver specs for the SD card, and most companies using SD technology are not implementing the controls yet, according to a source close to Zaurus developers.

The SD card wasn't the first memory card; in fact, the press release mentioned the MultiMediaCard as "gaining solid support as leading media" to meet the growing requirements for an expansion card that would increase the capabilities of PDAs, digital cameras, cell phones, and MP3 players. The MMC and the SD card both work in SD slots, they both transfer data at high speeds (although the SD card has the potential to transfer data quicker; most hardware does not use the full capabilities of the card), and they both support pure storage and applications. The MMC is slightly thinner and has seven pins for connection while the SD card has nine. Wes Brewer, SanDisk's board representative for the SDCA and the MMCA, says the SD card has the potential to function as a modem or network card, something that he says the MMC cannot do.

The SDCA press release implied that the only thing missing in the MMC was "copy protection" that would comply with the wishes of the Secure Digital Music Initiative (SDMI), which says its goals are to "provide consumers with convenient access to music both online and in new emerging digital distribution systems; enable copyright protection for artists' works; and promote the development of new music-related business and technologies."

The SDMI board is heavily populated with companies who are also members of the SDCA board.

The MMC also has its own board; it was created in 1997, also by SanDisk, this time with Siemens AG. In June 1999, BusinessWire ran a press release announcing that SanDisk would begin providing Panasonic with MultiMediaCards for its line of digital cameras. Andrew Prophet, executive director of the MultiMediaCard Association (MMCA), says he doesn't know why SanDisk decided to join with Panasonic a few months later to create the SD Card when the MMC card is virtually the same technology. "They decided they wanted to form an alliance with Panasonic," he says. "It angered many on the MMCA board."

SanDisk still sits on the executive boards of both the MMCA and the SDCA. Brewer says that, if people on the MMCA board were angry about SanDisk's actions in 1999, it wasn't apparent then.

The SDCA has grown quicker and seems to get more publicity than the MMCA; listed among its 387 members are such powerhouses as Microsoft, 3Com, IBM, NEC, Texas Instruments, Intel and the maker of the Zaurus, Sharp. Sharp, Microsoft, IBM, and Intel also sit on the board of the Secure Digital Music Initiative. Of these companies, only Intel is also a member of the MMCA -- not Microsoft, not IBM, not Sharp. This might be the reason that Sharp doesn't mention MMC compatibility in any of its product literature, although a company representative confirmed that the expansion slots, which are clearly marked "SD Card," will work with MultiMediaCards. She also said, "We will definitely incorporate [notification that the Zaurus is MMC compatible] into our future literature."

MMCA has recently implemented an SDMI-approved content copy control system for the MultiMediaCard, but as in the SD card, turning it on in the driver code is optional.

The bottom line for developers is, for full access to specs for the MultiMediaCard, they'll have to cough up $500 USD. But no NDA is required, and they don't have to become a member of the association, says Prophet, But the MMCA "would like their input and guidance on evolving the MMCA Standard." He adds that the MMCA is "OS agnostic," and that the MultiMediaCard is "ideally suited" for Linux platforms.

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