The report in this issue of LSN on LSSI's plans to use a videodisk as the storage medium for its data base prompted the editors to prepare the following summary on the potential of videodisks for data base publishing. Related information on various aspects of optical and digital disk technology has appeared in previous issues of the Newsletter.
The storage of digital data on optical media can take many forms. While most of the attention has focused on the optical digital disk, digital information can be stored optically on a variety of materials. There are companies that are recording the information on slides and on strips of film. The variety of ways in which the data are being recorded has led to a new generic descriptive term: optical mass memory technologies.
Most computer specialists look upon optical mass memory as nothing more than a computer peripheral device similar to magnetic disk or tape storage, but it can also be used in electronic publishing if an economical means of replication can'be found. Only one of the various optical media has to date been replicated in other than the laboratory:
the digitally encoded optical videodisk. The advantage of using a videodisk as the medium is that there is so much standard equipment available for it. Every other optical mass memory technology involves the building of special hardware.
The pioneering commercial effort in using videodisk for the storage of digital data is by LaserData (see LSN, Vol. III, No. 8, pp. 59—61). It has developed a system for encoding high-density digital information within the video signal of a 12-inch plastic video-disk and duplicating the disk on commercial “pressing” facilities of the type used for creating entertainment and training disks.
The company claims that the Laser-Data system hardware costs less than one-tenth that of magnetic technology or alternative optical mass storage technology; that its full-text storage capacity is 30 times that of high-density magnetic tape; 2,000 times that of double-sided, double-density floppy disks; and 3,000 times that of microfiche.
LaserData uses a videodisk player as a microcomputer peripheral device— the standard, low-cost, mass-produced optical videodisk player of the type produced by Pioneer, Sony, Magnavox, and others.
The data can consist of digitized images or it can be machine-readable data encoded character by character so that it supports full text searching with user-friendly dialogs. The system can accommodate a combination of digital and analog information. For example, it has the ability to store photographs and illustrations, both in still-frame and motion video formats—with or without accompanying text.
A LaserData 100 Controller with DataDisc Player costs approximately $1.30 per megabyte (one million bytes or characters) of data, assuming that 4,800 megabytes of storage are put on a disk. That compares with $35.00 per megabyte for an IBM 3380 magnetic disk drive.
LaserData DataDiscs are available in four data capacities: A-800, L-1600, A-2400, and L-4800. (Numbers refer to capacity in millions of characters.)
The LaserData DataDiscs may be single- or double-sided. One single-sided disk produced in quantity costs approximately $80. The capacity of the L-4800, the largest capacity disk, can be as much as the equivalent of 2 million pages of full text if double-sided storage is specified. This is a theoretical capacity: the actual capacity is reduced by 20 percent to provide for error correction.
The cost of the LaserData L-4800 itself is less than $.02 per megabyte as compared with $4.00 per million characters using a CX 9766 removable magnetic disk pack, $2.00 per megabyte using a floppy disk, and $.20 using high-density 6250 bpi magnetic tape.
One of the great concerns with the optical storage media has been the error rate. It is one thing to lose a few characters in the middle of an image, but another to lose characters in the middle of a stream of data that has been encoded character by character. LaserData claims that it can achieve an error rate comparable to that achieved with other optical media, or one error in less than 10 disks after correction.
Most machine-readable data are currently delivered to remote users by shipping magnetic tape via commercial couriers or transmitting data over voice-grade telephone lines. The former is an inflexible medium that requires reloading onto magnetic disk in order to manipulate it effectively. The latter is expensive--usually $5 or more per hour.
The primary market is seen as publishers of reference works, directories, text, and periodicals for medical, legal, scientific, academic, engineering, and business professionals. A wide variety of applications is possible because the DataDisc system can accommodate full text (searchable to the word, if desired), combined text/ illustration, and video in both still-frame and motion video format.
LaserData provides two services: the encoding of information onto Data-Discs and the supplying of equipment— the videodisk player, the microcomputer, and the unique controller that links the two.
The DataDisc Mastering Service (DMS) is a proprietary means of encoding information onto a LaserData DataDisc and then duplicating that master DataDisc in the quantities specified by the client.
The LaserData line of products includes nine distinct systems tailored to the differing needs of potential end—users. Most are configured in “workstation” form and employ a selection of optical videodisk players linked by the controller to a professional—standard microcomputer. The average work station costs approximately $18, 000.
The minimum hardware configuration for retrieving the data includes the LaserData 100 Controller—the hardware linking the videodisk player to the micro—and the LaserData 101 Professional, a work station with a microcomputer, one terminal, and a single videodisk player.
A more sophisticated configuration such as the LaserData 102 Researcher includes four DataDisc players to quadruple the online capacity for data retrieval. It can also support three additional terminals. The LaserData 301 is a complete image retrieval and analysis work station with four players, which includes image processing software, high resolution display capability, and monitors with touch—sensitive screens for interactive programs.
One of the other unique features of the system is an encryption process designated DataDefender. A disk publisher can put several data bases on a single disk and provide a customer the access “keys” only for those data bases for which the client has purchased the rights.
Despite the apparent breakthrough, potential users should proceed with caution. The successful publishing of data bases using an optical mass memory technology will depend on a variety of factors, among them technical soundness, cost, user acceptance, and adherence to standards—de facto or established. The market as a whole is likely to hold back, pending clarification in all of these areas.
Early entrants may find it necessary to provide their customers with the hardware as part of an annual subscription fee, rather than depending on them to invest in the purchase of equipment.
Considerable progress is being made in the development of other optical technologies—in capacity, error rate, ease of replication, permanency, and cost. Today's picture may change dramatically by 1985. The wise system designer will provide for a data base that can be stored on any of several media and retrieved on any of several micros or CRTs. The data base is the publisher's long—term investment and ongoing concern.
The ability to access information on hardware that is usable for many other applications is generally the overriding concern of the data base user. The era of dedicated terminals is ending. Even Mead Data—the highly successful producer of LEXIS and NEXIS—has decided to move away from requiring a special terminal to access its files.
Despite these caveats, the Laser-Data product line is an impressive entry in the optical mass storage technology market and warrants careful investigation by any potential data base publisher.
[Contact; LaserData, Inc., 1 Kendall Square, Building 200, Cambridge, MA 02139. (617) 494—4900.]
