|
|
|
| Reference Series |
Table of Contents For This Issue
|
|
| |
| How Computers Work, Part I | |
|
August 2001• Vol.5 Issue 3 Page(s) 60-65 in print issue | |
Shuffle The Deck Here’s The Deal Concerning PC Cards |
Portable computing is all about “less is more.” In addition to being more functional, portable devices are providing users more choices than ever, particularly with portable memory and accessories. An increasing number of portable devices now use cards that
users can quickly swap between devices or from device to PC. The trick is settling on a card format that fits your present and future needs.As an example, the portable MP3 player you just bought may use the removable CompactFlash format to store files. The Olympus digital camera you purchase later uses the removable SmartMedia format to store images. Neither format is compatible with the Secure Digital card socket on your new Palm m505 PDA (personal digital assistant). Obviously, a card that works with all your devices would be ideal, but it’s an unlikely possibility for now. Thus, you need to understand the benefits and detriments of each card family so you can decide which format can serve you best.
 The Birth Of Flash Media.
In general, small format cards are called “flash media” because of how they write data. Standard memory storage devices write data sequentially, or one byte at a time. Flash media records data in large flashes, ranging from 512 bytes to 256KB. In addition,
memory manufacturer SanDisk notes that the microchip used in such media erases a large swath of memory cells in a single action, or “flash.” The specifications for small format cards usually allow for more than just memory storage usage. However, memory
usually emerges as the first application for new card formats, so small media cards are typically grouped together and referred to as “flash media,” even though many have nothing to do with flash recording data for storage.By the late 1980s, it was clear to portable PC manufacturers that a standard removable media format was needed to solve the floppy diskette’s shortcomings, including its limited storage capacity. Numerous memory card solutions existed, but all were proprietary, meaning they only worked with the manufacturer’s products for which they were designed. In 1989, 25 vendors joined forces to formthe PCMCIA (Personal Computer Memory Card International Association; http://www.pcmcia.org). The following year, the PCMCIA released its first specification for a universal solid-state PC memory card. (Solid-state means the card can retain data indefinitely without battery power.) As products based on the specification began appearing, they were labeled as PCMCIA cards, a nonsensical mouthful for resellers and consumers. The PCMCIA soon promoted the term “PC Card.” Today, “PCMCIA” is used primarily to refer to the nearly 200-member organization. To date, there have been eight major revisions to the PCMCIA specification, spawning three main types of PC Cards: Type I, Type II, and Type III. All three have the same length (85.6 mm), width (54mm), and number of pin connectors (68). What varies is the thickness and applications. Type I cards are 3.3mm thick and are typically used for memory storage applications. Type II cards are 5mm thick and are intended for I/O (input/output) applications, such as fax/modem communications and network adapters. Type III balloons to 10.5mm thick, occupying the space of two Type II slots, and is generally used for rotating mass storage media, namely miniature hard drives. The width of the pin connector interface is the same for Type III cards, but the width of the foundation that houses the card’s inner workings is different. In 1995, the PCMCIA released the CardBus specification. In anticipation of more demanding future bandwidth needs, CardBus moved to a 32-bit bus operating at 33MHz, differing from the previous 16-bit PC Cards. The 32-bit bus is the same as the standard PCI (Peripheral Component Interconnect) bus. For throughput, it can achieve a 133Mbps (megabits per second) data rate. This number is significant because no other PC Card technology can meet the full data rate needs of 100Mbps Ethernet networks; only CardBus won’t create a bottleneck at the network adapter. PC Cards achieved another long-range breakthrough with the ZV (Zoomed Video) specification. The ZV port on a PC Card lets a video stream pass through the card into a notebook’s video frame buffer. The alternative is to send video through a conventional system bus, such as a PCI bus, which competes with other tasks working on that channel. The ZV port accommodates cards for external devices, such as TV tuners, MPEG (Moving Picture Experts Group) decoders for DVD (digital versatile disc) playback, and live video capture. However, advances made by video chipset companies, such as ATI and NVIDIA, surpass anything the PCMCIA envisioned in the mid-1990s. The result is video chipsets (when coupled with a high-speed external interface like IEEE 1394, or FireWire) in today’s notebooks being at or above the performance and functionality ZV might offer. Installing a PC Card is relatively effortless, and because the unit has an onboard CIS (card information structure) to tell the host system what the card can do and how to set it up, users just need to slide the PC Card into a compatible slot. The host recognizes it, the PnP (Plug and Play) operating system (such as Windows) integrates the card’s functions into the software interface, and the card is operating in about three seconds. Furthermore, PC Cards are hot swappable, meaning you can eject one and insert another without turning the host machine off. CompactFlash.
PC Cards are generally good for large devices, such as notebooks, but are too bulky for smaller portable devices. Not only was the PC Card significant in size, the host device’s pin connector and circuitry added even more size and weight. In 1994, SanDisk
(http://www.sandisk.com) released an answer to the PC Card with the smaller CF (CompactFlash) card format. The first generation Type I CF cards measured 43mm x 36mm x 3.3mm, or roughly the size of a small matchbook. Even better, the cards only weighed a
half-ounce, due in part to a move to 50 pins from the PC Card’s 68-pin connector. Because both technologies conform to the ATA (Advanced Technology Attachment) protocol, an adapter module lets CF cards function in a PC Card slot. CF Cards are rated to withstand
a 2,000G shock (equivalent to a 10-foot drop) and can last for 100 years under regular use with no degradation to data.The Type II CF card is identical to the Type I card, save for the card’s thickness, which is 5mm, the same as a Type II PC Card. Like PC Cards, smaller CF cards can fit into larger slots, but not vice versa. To date, most CF memory cards and I/O cards (network, serial, and cellular) have been Type I devices, but some new options have migrated to the Type II PC Card, including IBM’s Microdrive (http://www.ibm.com) and SimpleTech’s (http://www.simpletech.com) 448MB and 512MB solid-state CF storage cards. This application flexibility causes CF cards to vary in weight from 8 to 15 grams. CF memory gained early popularity in the digital camera market and in the first wave of portable MP3 players. But like PC Cards, a current trend places less emphasis on memory and more on I/O functionality. Current applications include Ethernet, laser scanning (bar codes), and cellular modem calling. In all of these uses except Ethernet, CF’s typical write speeds of 600KBps (kilobytes per second) to 800KBps are more than adequate, but the only devices that really require this functionality are relatively rare handheld PCs, found mostly in corporate settings. The speed issue bears some elaboration. The actual throughput rate of a card hinges on the controller technology integrated into it. As controllers improve, data rates go up, but most CF vendors make these upgrades as a matter of course without alerting the consumer. Lexar Media (http://www.lexarmedia.com), which integrates USB (Universal Serial Bus) technology into its controllers, is a notable exception. Lexar markets its CF cards according to speed ratings modeled after CD-ROM specifications, figuring a 1X speed to be 150KBps. Lexar 4X cards (600KBps) are priced in line with similar CF capacities from rival vendors, but 10X (1.5MBps) and 12X (1.8MBps) Lexar cards cost nearly twice as much per megabyte as competing brands. Interestingly, industry tests fail to show a substantial difference between low- and high-end Lexar media or a clear performance advantage of Lexar CF cards versus its competitors. The true benefit Lexar offers is that it bundles its a JumpShot USB reader cable with most CF modules to facilitate faster data downloading than conventional readers. Recently, as CF started showing signs of slipping in the market, two developments have thrust it back into the limelight. The first is IBM’s Microdrive technology, which packs a hard drive into a package small enough to fit in a Type II enclosure. The cost for such a drive is now about $400. The same amount buys about 300MB of solid-state CF memory, making Microdrive more attractive. The catch is that the Microdrive relies on moving parts and is more prone to damage. The other key development, announced in May 2001, is the adoption of optional security measures to the CF specification. Security is an increasingly critical issue in flash media, because without it, content developers have no way to protect the copyright of their works. For example, the MP3 format has proven to the music recording industry how easy it is to copy songs from PC to PC. Secure flash media would help minimize such a risk. For example, a user might have rights to copy a track from a purchased recording, but not the right to copy the copy. Without hardware capable of such DRM (digital rights management), securing content is impossible. The May 2001 announcement from the CompactFlash Association (the consortium that controls the technology; http://www.compactflash.org), details the adoption of the 4C Entity’s Content Protection for Recordable Media (CPRM; http://www.4centity.com) encryption method. The new standard, called Secure CompactFlash, will be entirely backward compatible and transparent to the user.
SmartMedia.
The size of a CompactFlash card is small compared to that of a PC Card, but SM (SmartMedia) is smaller still, measuring just 37mm x 45mm x .76mm. Toshiba owns the intellectual property surrounding SM, including the SmartMedia name, although the format’s true
name is Solid State Floppy Disk Card, a lengthy moniker that Toshiba decides to wisely avoid.Released in 1995, SM uses an 8-bit I/O interface based on a 22-pin terminal. However, there isn’t a grid of pinholes, as with the PC Card and CF. Instead, the format’s flat profile demands an interface based on twin rows of flat, gold contacts along the media’s bottom. The advantage is an interface virtually immune to problems, since there are no pins in the host device that can bend or snap off. Conversely, the super-flat profile makes it more susceptible to electrostatic shock damage. Under the hood, the differences between SM and CF are more evident. SM uses serial read/write architecture, whereas CF, like most flash media, uses parallel. Serial specializes in laying down sequential chunks of data extremely quickly. Parallel is better for fast random access tasks, such as locating a byte of data from within hundreds of megabytes. Digital camera vendors, such as Olympus, state that they prefer SM because of its faster read and erase times. Toshiba designed SM to be as simple as possible. Part of this approach meant removing I/O logic from the card and putting it instead in the host device. In other words, a SM card can’t access its own data; all of the circuitry, or brains, to do this resides in the device the SM card plugs into. This simplicity gives SM a price-per-megabyte advantage over CF. However, it also means host devices pick up the cost. For example, a USB card reader that lets PCs read flash cards much like a removable drive could cost two to four times more for SM than CF. Moreover, today’s SM capacities top out at 128MB, and there is speculation that future capacities at or beyond 128MB will be incompatible with today’s media. The SM specification references a “unique ID function” for security applications, but vendors have yet to indicate any kind of security functionality in their SM products. Perhaps because of these issues, Toshiba and the Solid State Floppy Disk Card Forum (http://www.ssfdc.or.jp/english) elected to make the licensing of the SM interface specification free to developers in an attempt to solicit new vendors. In contrast, SanDisk recently proved in an $8-million settlement with Lexar Media that it has every intention of enforcing its patent licensing rights over CF. Time will tell if this approach will keep SM viable in the flash game. Memory Stick.
Sony (http://www.sony.com) launched the Memory Stick flash media format in 1998, apparently with the intention to make it a SmartMedia killer. Like SM, the Memory Stick format is a serial write/erase flash device, but measures 50mm x
21.5mm x 2.8mm and weighs 4 grams. The interface has only 10 flat contact pins mounted on the card’s underside. The differentiating feature is the stick’s erasure protection tab (like those on floppy diskettes) mounted adjacent to the connector pins.In its first three years, the Memory Stick format amassed roughly $13 million in sales, according to Sony. This sounds considerable, but note that the Memory Stick is aimed at being a one-product memory solution across Sony’s entire consumer product line, including VAIO desktop PCs, CLIÉ PDAs, and MP3 players. Companies like AIWA, Fujitsu, and Sharp have signed on as licensees of the proprietary format, but thus far the only third-party products to emerge for Memory Stick is the flash media memory itself. Save for card readers, no non-Sony Memory Stick-compatible devices are on the market to date. Furthermore, Memory Stick has been saddled with prices at or above competing formats and a storage capacity reaching only 128MB during this year. Sony’s Web site sells the 128MB Memory Stick for about $260. SanDisk’s 128MB SM card retails for about $160 and is more widely supported. Don’t count Sony out yet, though. With the race for secure flash media in full swing, Sony was first to market a solution called MagicGate. This solution is compatible with specifications of the SDMI (Secure Digital Music Initiative; http://www.sdmi.org), an industry-wide effort to devise safeguards for copyright protection, which is also backed by the 4C Entity. MagicGate is an enhancement to the Memory Stick format and makes no changes to the external design, save for the words “MagicGate” printed on the top. However, each MagicGate Memory Stick has a unique ID (identification) number and an encrypted recognition technology to determine if the host device is MagicGate-compliant. MagicGate also relies on Sony’s OpenMG copy protection software platform to prevent unlicensed file duplication. (OpenMG is free to developers, but MagicGate technology is not.) Additionally, Sony appears to be meeting consumer complaints that existing flash solutions are still too large for devices such as audio players and cell phones. In response, Sony designed the Memory Stick Duo, the smallest flash platform yet. Duo measures 31mm x 20mm x 1.6mm and weighs only 2 grams. The format, which also incorporates MagicGate, is expected later this year in capacities ranging from 8MB to 64MB. The sticks can fit into standard Memory Stick slots with an optional adapter.
MultiMediaCard & Secure Digital.
In 1997, SanDisk and Siemens AG joined forces to release the MMC (MultiMediaCard). Weighing just 1.5 grams and measuring 24mm x 32mm x 1.4mm (about the size of a postage stamp), MMC was originally designed as a memory solution for smart digital cell phones.
MMC uses a 7-pin flat contact connector, which is sufficient for most casual tasks. Like SM and Memory Stick, MMC is a memory-only format.The MMC alliance had two halves. SanDisk produced the flash memory products, which currently reach up to 128MB, while Siemens handled ROM applications, such as e-books, maps, reference materials, and other software titles. Unfortunately, the market for portable readers never solidified. Without a persuasive advantage over existing platforms, MMC languished during its first three years, only to gain recognition in late 2000 as consumer devices finally started running into form factor barriers caused by storage media. As with SM, MMC has a rudimentary ID function, but no advanced security features, which is a setback at a time when security is becoming paramount. SanDisk has teamed with Matsushita and Toshiba to create an MMC offshoot called SD (Secure Digital). SD uses the same length and width as MMC but has a 9-pin connector and 2.1mm thickness. As such, MMC cards will fit in SD slots, but SD is incompatible in MMC slots. The slight boost in form factor goes a long way, though. SD is compliant with both SDMI and CPRM and is license-free. The complete specification is available to any developer who pays to join the SD Card Association (http://www.sdcard.org). The CPRM format creates encryption using a series of keys spread over three categories: device, media, and content. Device keys are issued by the 4C Entity to a specific manufacturer for inclusion in each of the vendor’s devices, which is a similar technique to MagicGate’s method. However, each SD card has four data areas: Hidden, Protected, System, and User. Normally, a read/write device has read-only access to the System area and is barred from the other three, but this is enough to access the System area’s Media Key Block. The device key contained in the portable device talks with the Media Key Block, and an algorithm generates a private Media key. If this Media key matches the keys contained in the Hidden section, the device is given access to the SD Card Protected area. The ingenious part of the process is that SD designers know hackers will ultimately break the encryption algorithm and be able to discern secret device keys. However, SD cards are self-healing. When it becomes known that a hacker has obtained a certain device key, content vendors can apply new values to the Hidden section that cause the hacked device key to generate faulty secret key values, which are rejected by the card. Is security alone enough to defeat competing standards? If it isn’t, SD has a few other trump cards to play. For starters, SD has a higher tolerance against electrostatic shock than other formats and offers a write-protect switch. Today, SD sports a 2MBps data transfer rate. This is in line with other formats like Memory Stick, which offers burst rates of 1.8MBps (write) and 2.45MBps (read). But SD will migrate soon to a 10MBps path, making it suitable for applications beyond that of memory storage. Secure Digital scored its first coup when Palm (http://www.palm.com) released its new m500/505 family of PDAs, which boast an SD slot. Currently, the SD options in the Palms cover memory storage and read-only software. Soon, however, expect SD to follow the CompactFlash path and offer GPS (Global Positioning System) receivers, wireless modems, barcode scanners, Bluetooth adapters, and more. In The End.
There really are no bad choices when it comes to today’s flash media options. MMC is quickly giving way to SD, and SD and CF both stand to take over the PC Card’s wide array of applications as circuitry continues to shrink. Without a clear advantage over
competitors and continued foot-dragging from partners, Sony’s Memory Stick faces an increasingly steep battle despite its marketing abilities. Regardless of format, all the options offer a substantial value to users. 
by William Van Winkle View the graphics that accompany this article. (NOTE: These pages are PDF (Portable Document Format) files. You will need Adobe Acrobat Reader to view these pages. Download Adobe Acrobat Reader) View additional graphics that accompany this article. (NOTE: These pages are PDF (Portable Document Format) files. You will need Adobe Acrobat Reader to view these pages. Download Adobe Acrobat Reader)
|
