You're scheduled to present your latest IC design to the rest of the team this afternoon. Using electronic-design-automation software and Sony's MD Data portable data-storage and -retrieval system, you put the finishing touches on the project and save the files on a 2.5-in. MiniDisc. At the presentation, you pop the disk into a portable MDH-10 disk drive attached to your laptop and pull off the design presentation without a hitch. After dinner, you grab the MDH-10, throw on a pair of headphones, and update your work while listening to your favorite concert bootleg or Beethoven symphony.
With the MD Data system, which Sony introduced to OEMs in March, and the MDH-10, the first battery-operated, portable MD Data drive, 140-Mbyte, rewritable data storage and retrieval is easy and efficient. MD Data is a low-power, compact system based on Sony's MiniDisc digital-audio technology. With a 2.5-in. MiniDisc and a $699.95 MD Data system, you can record and rerecord disks more than 1 million times without loss of data integrity.
The MDH-10, which will make its retail debut in early 1995, is portable and compact; at 1.2×3.3×4.9 in., it's a bit smaller than a Walkman portable stereo. It suits a variety of business and consumer applications from notebook and laptop PCs to multimedia presentations.
Takashi Sugiyama, director of multimedia peripherals marketing for Sony Electronics, says that MD Data's portability and capacity improve the way users store information on the go. "MD Data is the first portable, high-capacity rewritable storage; it has the potential to be the floppy disk of the multimedia age," he says.
On-the-road convenience
What is revolutionary about MD Data is not its technology but its convenience and interoperability: The system's capacity is comparable to the amount of data you could store on 100 floppy disks. In addition, because the MD-10 is portable, mobile users simply plug it into their laptop and notebook PCs to create presentations, update client files, or play back multimedia applications anywhere. And, with lithium-ion batteries, you can run the unit for two hours before recharging.
"MD Data's portability and cross-development with audio means compatibility with additional application areas, such as in multimedia, where PC and audio integration are becoming the norm," says Sugiyama.
MD Data uses data compression to accommodate 74 minutes of playback, the length of a standard CD, onto its 2.5-in. disk format (see box, "1970s technology positions MiniDisc for 21st-century applications"). Media formats include rewritable magneto-optical for personal data-storage applications, read-only for electronic publishing (CD-ROM) and prerecorded-software applications, and hybrid (partially rewritable) for interactive applications (read-only parts prevent accidental erasure).
MD Data uses magneto-optical-disk technology to rewrite disks in a single pass, saving power. MD Data's recording density and linear velocity are comparable to standard CD technology. In addition, you can assign and reformat addresses after rerecording a disk.
For portable applications, MD Data's hardware and disks are shock-proof. MDH-10 has a SCSI-2 interface to accommodate standard laptop, notebook, and subnotebook computers. MD Data's drive has a 150-kbps data rate and 300-msec average access time, significantly slower than the 15 msec of magnetic disk drives.
You power the system with a rechargeable lithium-ion battery pack, an ac power adapter, or three AA alkalines. MDH-10 comes with installation software for DOS/Windows and Macintosh systems; for $699.95, you also get a pair of headphones to use MD Data as a music MiniDisc player. MD-140 rewritable media costs $29.95.
Several software companies plan to work with Sony to develop products for MD Data. George Siegle, marketing manager for Deneba Software in Miami, says that Deneba's Canvas software for Macintosh and Windows systems teams nicely with the MD Data technology. Engineers use Canvas software for high-tech precision drawing, bit-map editing applications with detailed color graphics, and graphic design.
"A lot of our files are extremely large and sophisticated, and we're excited about MD Data because users can popin disks and easily transport their files," says Siegle. "Storing and retrieving large data files on floppies just isn't practical. Canvas users benefit from MD Data's large storage capacity. It's a convenient and fairly economical way to save and transport enormous amounts of information." Siegle also thinks that demand for MD Data in the business com-munity will spread rapidly, based on the system's con-venience.
MD Data also works well with WordPerfect's Envoy electronic-document-management system. MD Data and MDH-10 offer more storage capacity for Envoy, as well as a range of WordPerfect-related applications. With MD Data, users can store thousands of large, complex documents on one disk.
Graphic designers who work with Adobe Systems' Illustrator, Premier, and Photoshop software can also benefit from using MD Data. Such users typically experience frustration with files too large to save and transport via floppy disk. MD Data's capacity and portability offer artists and designers a compact data-storage alternative.
Sony has tentative plans with Microsoft to develop MD Data file systems for MS Word and Windows NT and Windows 95 operating systems. At IBM, designers are modifying MD Data's internal drive for ThinkPad mobile computers, accommodating multimedia peripherals, such as CD-ROMs and hard disks.
Additional uses for MD Data include photocopiers, fax machines, printers, personal digital assistants, and interactive and imaging applications.
The benefits of disk rewritability and portability are beginning to catch on with consumers. Since the debut of MiniDisc technology a couple of years ago, Sony has sold more than 400,000 MiniDisc players worldwide. If MiniDisc-player cloning by Aiwa, Sanyo, and Sharp parallels MDH-10's spread in business applications, Sony can look to portable data-storage and -retrieval as a market that's rife with potential. MiniDisc's rewritability and size will remain among its biggest sell- ing points for high- and low-tech consumers alike.
When Sony introduced its music MiniDisc to the consumer market a couple of years ago, audiophiles were less than awed by Sony's technological "breakthrough." Partly to blame was Sony's touting of 20-year-old technology as MiniDisc's claim to fame.
MiniDisc's development stretches back into the late 1970s, when Sony R&D began developing an optical-disk product for recording and rerecording. By 1988, the company had introduced a rewritable magneto-optical disk for computer data storage. Finally, in 1992, MiniDisc made its debut, following the birth of the CD by about 10 years.
To design MiniDisc, Sony combined a variety of older, readily available technologies and manufactured the device using modified CD-production techniques. For a variety of reasons, including initial product cost and the media's lukewarm reception to MiniDisc as a revolution in audio technology, consumer demand has been slow to grow.
Sony released two versions of MiniDisc: playback-only, geared to the music industry, and recordable, for high-tech and computer data-storage and -retrieval applications.
A MiniDisc measures 64 mm in diameter, which is approximately half the size of CDs. Similar to the length of a standard CD, MiniDisc handles 74-minute playback. But MiniDisc stores this amount of data using recording techniques technically different from those of CDs.
To record and rerecord data, MiniDisc depends on magnetic-field-modulation technology. Magnetic-field-modulation overwriting uses a laser on one side of the disk to apply heat to a specific location and "loosen" old data on the opposite side. A new magnetic field then maps to that assigned location. Because a magnetic recording head and laser work simultaneously on opposite sides of MiniDisc, the disk's shutter opens on both sides.
MiniDisc's shock-proof solid-state design suits it for portable handheld applications. A MiniDisc player uses semiconductor memory as a shock buffer. Its 1-Mbit memory holds an amount of data equivalent to 3 sec of playing time before sending the data for D/A conversion. If the pickup loses its position, or if an interruption in data flow occurs, semiconductor memory flows data back at a 0.3-Mbps rate. Once the laser resumes its original position, it reads data from the disk at 1.4 Mbps, replenishing the memory in less than 1 sec.
To fit MiniDisc's digital data into its compact size, designers turned to a data-compression technique called adaptive transform acoustic coding (ATRAC). ATRAC enables MiniDisc to read data at 1.4 Mbps; because playback takes only 0.3 Mbps, MiniDiscs deliver digital sound reproduction using one-fifth the amount of data previously required.
ATRAC is essential to MiniDisc sound integrity. Music that records digitally on a MiniDisc differs slightly from read-only music on a CD. This difference is due to increased levels of quantization noise resulting from MiniDisc's size.
ATRAC successfully adapts audio signals to a human ear's sensitivity to varying frequencies. Because the human ear is most sensitive to frequencies near 4 kHz and less sensitive at higher frequencies, a 4-kHz tone audible at one power level may be inaudible at the same power level, but at a different frequency. Similarly, quantization noise may be audible at one frequency and inaudible at another.
ATRAC adapts audio signals to the ear's changing sensitivity by hiding quantization noise in frequency regions where high signal levels correspond to musical activity. When music records on a MiniDisc, ATRAC analyzes the music signal and determines frequency-region sensitivity. ATRAC ensures that sensitive regions are recorded accurately and sacrifices accuracy in other regions, where the ear is less sensitive. Based on this principle, ATRAC renders MiniDisc quantization noise inaudible, ensuring that sound quality matches that of a CD. In addition, ATRAC features nonuniform time-splitting, allowing analysis of 1.45- or 2.9-msec blocks of time to keep up with rapidly changing or vivid music passages.
MiniDisc's modulation system converts 8-bit encoded signals into 14-bit signals to match digital signals to disk transmission characteristics. It uses Reed-Solomon Code for error correction. ATRAC-reduced audio data group into blocks for recording in a format similar to the CD-ROM mode 2 standard.
1970s technology positions MiniDisc for 21st-century applications
You can reach Senior Associate Editor Jim Leonard at (617) 558-4324, fax (617) 558-4470, or via Internet on MCI mail at ednprime.