Eight great levels - Storage Watch

Computer Technology Review, Feb, 2002 by Hal Glatzer

Some advertising catch-phrases stick in your mind forever. One of my 'all-time favorites was created for Contadina Tomato Paste, many years ago. It asked, rhetorically: "How'd they put eight great tomatoes in that little bitty can?"

Which is what popped into my head while I was talking with Ken Campbell, the president and CEO of Calimetrics, Inc. (Alameda, CA). His company has developed a chip--an application-specific integrated circuit, or ASIC--for otherwise ordinary CD-R/RW drives that, in effect, makes each spot on the recording layer do the work of eight. And that, in turn, enables a tripling of storage capacity, so a specially-formulated 120ram (CD-size) disk can hold 2GB of user data.

TDK (of Tokyo, and Garden City, NY) is the first OEM to announce that a drive so equipped will be available--in Q2--and that it will carry a highly competitive retail price of $199. TDK-branded 2GB write-once media will list for $1.99 apiece; rewritable media for $2.99. Of course, the drive will also read and write conventional CDs, but (no surprise) those 2GB disks will work only in drives that have the Calimetrics ASIC aboard.

The enabling technology was developed about ten years ago, at the University of California at Berkeley, where two researchers enhanced microscopes with laser interferometry, a technique for measuring tiny differences in reflectivity. The university patented that application, and put in a claim to apply it to optically reflective surfaces, including those in data storage media. It also granted the researchers a license to use the technology, when they left to start Calimetrics.

Their first R&D efforts focused on CD-ROMs: varying the depth of pits changed their level of reflectivity, which could be interpreted in a range from "flat"--no pit--meaning "zero," down to the deepest pit, meaning "eight." With this ability to express up seven binary numbers they could assign any one of three distinguishable data bits to an) pit--giving each pit three possible meanings, instead of just one.

Same Ingredients--New Formula

CD-writers don't make pits, however; so the R&D people at Calimetrics developed a chip for guiding a write-head to produce dynamic range of "colors"--shades of gray, actually--in the recording layer of CDs, both in write-once (dye-based) CD-R media, and in rewritable (phase-change alloy-based) CD-RW media.

"We create a slightly smaller bit cell than what's standard," Campbell explained, "and we 'color' it by making the mark darker or lighter, in one of eight ratios of light to dark. The underlying 'write strategy' is a combination of laser power and pulse duration that works like a printer: the more marks, the greater the density, and the darker the spot. With fewer marks, you have lower density and a lighter spot."

Calimetrics calls its technology "ML" for "multilevel" recording. (Don't confuse that with the multiple recording layers that DVD researchers are working toward--there's just one recording layer in ML media.) Interestingly, as Campbell noted, "ML media are made by the same machinery as regular CD media We use the same components in the recording layer, too--the same dyes or alloys--but in a slightly different mix." Mitsubishi Chemical, of Japan, is making the TDK-branded media.

They, along with Calimetrics, are partners in the newly-formed ML Alliance of (mainly) Japanese manufacturers. Sanyo Semiconductor--a Calimetrics, investor--is making the ASIC; Shinano Kenshi Co. Ltd., is building the drive for TDK through its Plextor subsidiary (so there could be a Plextor brand, later in 2002). Others include MKE (Panasonic), Yamaha, Sanyo Drive Co., and TEAC.

So far, two software developers--Roxio and Ahead--are adding 2GB extensions to their CD-writing utilities; and it's Ahead's "Nero" software that will ship bundled with the TDK drives. (Technically, the 2GB of user data comes from a total of 2.28GB, the remainder being needed for overhead.) At launch in mid-year, there will be 120mm 2GB disks, and 80ram 650MB disks available, with a 60mm 200MB "business-card-size" version due later.

A "MultiRead" Or A "Superfloppy"?

What's interesting to me about the ML breakthrough is that the extra storage capacity comes not from pushing the recordable real estate further to the edges, nor from tightening the track pitch to boost the areal density. It comes from using each pit more efficiently--or, as Campbell put it, "by increasing the linear density." That gives the drives yet more value, by trebling their write speeds over conventional CD recorders. The first version of the drive is specified to write to write-once media at 36X, and to rewritable media at 24X.

Unknown, at this point, is how well the ML concept will appeal to integrators and users. The 2GB disks are incompatible with the vast installed base of CD readers and writers; but there's no significant cost penalty for a drive with the ability to record them; and the media, too, is budget-priced. So ML capability could slide gracefully into the marketplace, over time, in much the same way that "MultiRead" (-RW) capability did. Of course, unlike MultiRead, ML doesn't have market leaders Sony and Philips behind it. But the roster of ML Alliance partners does include practically every other major player.