Sony Corp’s Sony Components & Computer Peripherals Co UK is coming out of the closet so to speak with its new range of erasable magneto-optical drive systems which are the first to be marketed under its own brand name. Until now the company has concentrated on supplying OEM customers – it supplied the optical drive in the ill-fated first generation of Steve Jobs’ NeXT Computer System – but it reckons its name will be an important selling point for the new systems, which will be available to distributors in niche markets as well as to large end-users. Erasable optical disks were first introduced in 1988 and are set to revolutionise the data storage market, according to Sony. It is concentrating its efforts on magneto optical products that it says offer virtually unlimited rewrites and greater reliability than other available optical technologies. It forecasts that the medium will account for up to 20% of the total UK data media market by the end of 1993, with 8% of that figure made up by platters for the 3.5 form factor. The worldwide market this year, it estimates, will be worth UKP500m.
Biasing
Magneto-optical recording systems work by using the heat from a laser beam together with a specially applied magnetic field to change the direction of the magnetic domains on the disk. A weak biasing magnetic field is applied to the disk which is pre-magnetised in an upwards direction. The laser beam rapidly heats a spot on the disk which, when it reaches a certain point – the Curie point – changes its magnetic orientation as determined by the biasing magnetic field. When the beam is removed, the exposed disk region returns to a normal temperature and a magnetic spot remains. It is by this process that data is written to the disk. When re-heated and exposed to a magnetic field of opposite orientation to that for recording, the disk returns to its original state. A lower intensity laser beam is also used to read the disk. The reflected beam is polarised clockwise or anti-clockwise according to the direction of the magnetisation – which will be either upwards or downwards – on the disk. This is then analysed and interpreted as binary data. The new Sony drives come in both 3.5 and 5.25 form factors and they offer a choice of AT, Micro Channel or Macintosh interface.
By Lynn Stratton
All conform to the International Standards Organisation norms for magneto-optical disk cartridges. The 3.5 RMO-S350 stores up to 128Mb of fully re-writable data – about 100 times the capacity of a conventional 3.5 floppy and offers a seek time under 40mS and bit error rate of less than 10-to-the-minus-12. Maximum burst transfer rates are 3M-bytes per second asynchronous and 4M-bytes per second synchronous and data transfer rates are 6.25Kbps. The drive measures 9.8 by 2.9 by 11.2 and weighs 2 lbs. The 5.25 RMO-S550 stores up to 650Mb (1,024 bytes per sector) or 594Mb (512 bytes per sector) on a single-sided disk. It has a 70mS seek time and the same error rate as the RMO-S350. Data transfer rate is 680Kbps at 1,025 bytes a sector or 620Kbps at 512 bytes per sector. It measures 8.3 by 3.9 by 11.4 and weighs 2.6 lbs. Both drives come with Sony’s RMOS software driver that enables users to format and initialise disks either like hard disks with multiple partitions, or floppy disks without partitions. It also enables users to import files from several rewritable optical disks without having to boot the computer with every disk change; to establish MS-DOS and non-MS-DOS partitions – for Apple personal computers for example – on the same disk. An SCSI board and cable, and user guide are also included in the driver kit – and hotline support will also be available to end users needing advice on installation. The 3.5 format drives range from UKP1,450 to UKP1,900; the 5.25 format dries are between UKP2,250 and UKP2,700. Sony’s magneto-optical platters are ISO/ANSI compliant and guaranteed 100% error-free. They are ruggedised against shock and have a special shutter lock mechanism that keeps dust out. Sony says they have a standard life of over 1
0m writes and rewrites, and up to 15 years archival life.
Tertiary
Their speedy data transfer rates are achieved partly by spinning at 3,000rpm, rather than the conventional 1,800rpm to 2,000rpm. The 3.5 platter costs UKP50; the 5.25 is UKP120. Though less suitable in terms of its Gigabyte capacity and seek times for secondary storage, optical technology is ideal for mass, portable tertiary storage, Sony believes. This makes it a likely replacement for tape back-up systems, with the advantage of being random rather than sequential access, and an ideal medium for data-intensive personal computer and workstation applications like computer-aided design, desktop publishing, multimedia and database management. Other likely applications include back-up systems for financial companies; software distribution; data collection for the oil industry; security-critical data storage for government departments; and storage of medical X-ray and computerised axial tomagraphy scanner records. Sony says it is hoping to increase its overall share of the both the 3.5 disk market from 33% this year to 57% in 1995 and the 5.25 market from 37% in 1993 to 46% in 1995, so establishing itself as the leading supplier of optical storage products. It says it now has a drive that stores 1.3Gb, which will not be released until suitable standards are agreed.
