Today, billions of chips in computers, automobiles, cellphones, media cards, and those clever key-chain memories, store data and instructions in the absence of power, ready to go to work at the flick of the on-switch. They are almost all flash chips, a type of electrically erasable and programmable read-only memory. Nonvolatility, flash's property of retaining data for years when unpowered, is crucial for most electronic systems any more complicated than a light bulb.
A flash chip in a computer tells it how to boot up. In a cellphone, it holds the instructions and data needed to send and receive calls, and stores phone numbers. Almost as important as flash's nonvolatility is its programmability, which lets users add addresses, calendar entries, and memos to PDAs and erase and reuse media cards.
But flash is under assault by technologies bent on proving they can do better. The ferroelectric memory picks up on the electric fields inside certain atoms and the directions in which they point. The magnetoresistive type stores data as the either-or directions of the alignment of small magnetic regions in a ferromagnetic material. A third, Ovonic Unified Memory, is based on a material that switches between crystalline and amorphous bases.
Different as these technologies are, they share two advantages over flash. First, they can write data in a few tens of nanoseconds, like the dynamic RAMs in a computer's main memory. Flash, on the other hand, takes at least a nanosecond. Second, the new memories can withstand constant rewriting for years, whereas flash cells begin to lose data after fewer than a million write cycles--suitable for media cards and cellphones, but not for a computer's main memory, which is constantly rewriting the data in memory cells.
In contrast, the newcomers endure for a practically limitless number of write cycles. That endurance, together with their reasonable write speeds, takes them beyond flash to tackle the broader dynamic RAM market as well. A veritable pot of gold awaits such a successor to flash and DRAM. Taken together, flash and DRAM sales, which represent about 15 percent of the total semiconductor market, were projected last November by International Data Corp. (Framingham, Mass.) to total over US $22 billion in 2002 and exceed $25 billion in 2003. The big unanswered question is which one--or ones--will succeed.
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