A few years ago, the memory-card market for digital cameras was up for grabs as competing formats fought for industry acceptance. Today, it's much less of an issue, as CompactFlash cards, introduced by SanDisk Corp. in 1994, are now used in more than 70% of all digital-camera designs, according to International Data Corp., Framingham, Mass.

Thanks in part to the growing popularity of DCAMs, CompactFlash shipments are expected to jump by more than 1,600% in the next few years, from 1.7 million units in 1997 to 28 million in 2002, according to IDC.

"This form factor is here to stay," said Samuel Nakhimovsky, product marketing manager for flash cards at Silicon Storage Technology Inc., Sunnyvale, Calif. Last June, SST jumped into the CompactFlash market with a line of memory cards.

What's driving OEMs to CompactFlash? Price certainly isn't the key. CompactFlash cards cost about $7 per Mbyte (Phils note: funny, I've just seen 64MB Lexar CF for $160 which is $2.5 per MByte), while competing small-format cards, such as SmartMedia cards from Toshiba Corp., sell for about $3 per Mbyte.

But CompactFlash, in addition to its tiny, matchbook-size format, has much greater storage capacity than its competitors. Last November, SanDisk brought to market CompactFlash Type I cards that hold up to 96 Mbytes of data, and the company is promising to double capacity again this year. At the same time, a number of competing vendors have announced product roadmaps that will take them to gigabyte capacities within the next two to three years.

The higher-capacity cards will prove particularly useful to camera users moving to high-resolution, megapixel cameras, said Nelson Chan, vice president of marketing at SanDisk. "When set at their highest resolution, those cameras typically require a megabyte or more of memory to capture and store each image," Chan said.

While capacity is certainly a key issue, access speed is also becoming an important design characteristic, and is a major way in which CompactFlash manufacturers can attempt to differentiate their products. At the same time, new, higher-resolution picture files pose a significant design challenge for engineers attempting to meet users' demand for greater access immediacy.

Some companies are already attempting to carve a niche for themselves as manufacturers of high-speed memory cards. At a time when the average CompactFlash card offers a sustained write throughput of about 500 Kbytes/s, SST is bringing to market cards with throughput rates of 1.4 Mbytes/s.

"That capability will really come into play with the next-generation digital cameras, when the file sizes become large enough that you will notice a difference between a fast and slow CompactFlash card," Nakhimovsky said. "The bigger the buffer and the better the firmware a vendor has, the better able you are to address the memory, and that difference shows up in better performance."