Exotic Opticals New Within Reach

Computer Technology Review, Jan, 2001 by Hal Glatzer

Cool products on the way

Really exotic storage technologies never seem to leave the lab: the world is still waiting for holographic cubes and biochemical tubes. And at the end of every year someone trumpets a breakthrough, but invariably it's at least two years away.

In November Sony announced ultra-density optical (UDO): a phase-change recording scheme for storing at least 40GB (20GB/side) on 5.25-inch media. Projected to arrive around the end of 2002, UDO drives and disks would be the same size as those of today's MO. That will make jukebox vendors happy, though in every other way UDO is incompatible with MO. The core technology (without which UDO goes nowhere) is what Sony calls "a 405nm violet laser".

HP and Plasmon have announced support, but I'm not holding my breath for the product. A longer-wavelength "blue" laser diode, which by itself could quadruple today's optical storage densities, has yet to be commercialized even after ten years of R&D.

But there is a next-generation of storage devices that is either shipping now or can come to market within the next twelve months. Some are innovative applications of existing technologies and others are genuinely new approaches to data recording. They're worth paying attention to now because they're consistent with at least one of the three benefits that the best storage products offer: portability, compatibility, and synthesis.

Portability

There's a practical limit to how small a portable computer can be: real fingers have to work the keyboard. Make the computer any smaller, like a palmtop, and you need a stylus to touch the buttons or the screen. But the only size requirement for a removable storage device is at the connector end.

Agate Technologies Inc. has just released a small solidstate storage device called Q. Banking on the fact that every PC and laptop made since about 1998 has a USB port, Agate (pronounced "ah-GAH-tay") made Q terminate in a standard USB connector. The core product holds 64MB and retails for $199, although there is a 16MB alternative for $69. A 32MB version for around $100 and a 128MB model for around $300 are due later in 2001, but Agate is already talking to vertical-market systems vendors about making branded or custom devices in any available chip capacity.

Mounted inside a Q is a NOR semiconductor memory chip, its attendant controller chips, and the USB bus circuitry. But a Q is the size of a grownup's thumb: about two inches long, less than an inch wide, and less than half an inch thick. It's also concave on one side, so it feels like those smooth stones that people rub for good luck. And like a charm, it could be hooked to a key-ring through a loop at the opposite end from the USB connector.

So a Q is oddly shaped and larger, compared to a CompactFlash or SmartMedia card. But the user doesn't need a "reader" accessory for it-- neither an insert to a drive bay, nor an adapter in the PC Card or floppy-disk form factor-- just a USB port.

And with Q being truly thumb-sized, Agate's VP of Strategy Jim Plant is exploring the possibility of adding a biometric security sensor to the plastic housing: specifically a thumbprint reader. That would enable it to read or write data only in the hands (literally) of one designated user. "With all that memory on board," he told me, "Q could hold most of a patient's medical records, including some scanned images. And as a substitute for an ATM card, it would be a whole lot smarter than the smartest smart-card."

Compatibility

Technically the only thing harder than making a new optical storage device is making it backward-compatible with something else. And marketing-wise, you can't count on owners of legacy data rushing to make their old media obsolete. (That's why I'm not sanguine about Sony's UDO.)

But a company called Calimetrics is promising to triple the capacities of nearly all of today's optical storage systems, some time in 2001-- at an extra cost to drive manufacturers of what chairman Tom Burke projects will be only a $20 chipset.

"We've shown that we can write to any media that's based on spot reflectivity, including dye-based write-once media like CD-R and DVD-R, and to phase-change media such as rewritable CD and DVD-- including Sony's proposed double-density CD media. What we can't write to," Burke acknowledged, "is MO media."

Here's how it works. Traditionally a recorded spot is either highly reflective or it's not, so it can be interpreted in just two ways (a logical one or a logical zero). Calimetrics's approach is called "multilayer" recording, but it doesn't involve multiple recording layers. As Burke explains it: "If a spot exhibits one of eight different levels of reflectivity-- that is: one of eight states of grayness, in a range of lightness to darkness--it can be interpreted in eight different ways. Eight is 'two-to-the-third power,' which means that the spot can be recorded as any one of three distinct data bits.

"The transfer rate goes up too," he noted, "because, at any given rotational speed, we can record three times faster. Theoretically we could read data three times faster, but in reading we're limited more by the data rate of the drive's internal controller, bus, and so on. The important thing to remember, however, is that everything else is the same as in a conventional drive and that it will still write and read its standard media."