It’s taken just one year for IBM Corp to double to 11.6 billion bits – or 1.45 gigabytes – the amount of information that can be stored on a square inch of magnetic disk. IBM passed the five billion bit level in December 1996 and has previously said it would use a new technique to build 2.5 hard disks for portable computers that can store 6.5Gb data by 2001 incorporating future versions of its pin-sized Giant Magnetoresistive (GMR) heads (CI No 3,287). IBM says it used an advanced version of GMR to read data stored in the new 1.45Gb per square inch technology plus new channel electronics techniques. It can pack 315,000 bits per inch on track on the disk; 36,800 tracks per inch of disk. A 3.5 disk using the new technique will hold up to 13Gb. By IBM’s reckoning every square inch of disk space could store 1,450 novels. IBM director of storage systems and technology at the Almaden Research Center in San Jose, California, Currie Munce told Computergram that using the same processing and read/write techniques and today’s materials storage density of 40 billion bits per square inch – 5 gigabytes – would be achievable in the near future. With new coding, read/write and materials densities could easily extend and order of magnitude further, IBM said. The theoretical limitation of magnetic storage techniques is that when bits get very small their energy becomes indistinguishable from background energy and then bits are likely to change state at will. Munce said the announcement demonstrates clearly that magnetic storage techniques will remain more advanced than both semiconductor-based solid state (flash RAM) and optical (CD-ROM) storage technologies. Flash RAM is useful and cost-effective for storing small quantities of data, such as 2Mb or 4Mb, but is prohibitively expensive thereafter, typically 30 to 50 times more expensive. Optical storage hasn’t kept pace with magnetic storage, Munce claims, which is doubling every 18 months. Magnetic storage has caught up and surpassed optical storage densities in the last seven years, he says. Munce’s team is now looking at holographic storage techniques which can store information not simply in surface bit volumes but in metric densities. Although traditionally known for its skills in developing ever more massive mainframe systems IBM clearly recognizes future success will depend largely on its ability to develop smaller and faster technologies. Storage and software is a chicken and egg situation. As data storage capacity increases so software developers write bigger programs that require larger disks. The 5Mb magnetic drive IBM introduced in 1956 cost $10,000. By 1991 average disk drive capacity was 145Mb (or $5.23 per megabyte), reaching 2.65Gb ($0.10 per megabyte this year).
