Sony says engineers at its research labs have made a breakthrough in magnetic tape data storage that paves the way for backup cassettes with capacities of up to 1TB, many times that of current systems. The company said it has succeeded in recording data at a density of 6.5GB per square inch on a newly developed tape - around 17 times the density of Sony's highest capacity existing commercial tape which is based on the AIT2 (Advanced Intelligent Tape) format. AIT2 offers a capacity of 50GB per tape. AIT3 and AIT4 formats are under development and will offer tape capacities of 100GB and 200GB per tape respectively but Sony's technology goes beyond this. Translated into an 8mm cassette, the new technology will make possible 1TB tapes - but not for a few years yet. Sony had to clear a number of hurdles in order to achieve the higher capacity, said company spokesman Masami Kato. The biggest of these concerned noise. At such high data densities, the effect of noise is much more pronounced and can easily interfere with data on the tape. To solve this problem, the company worked on a system that ensures the magnetic coating on the plastic tape is distributed evenly and completely aligned. The second big problem for the engineers came from static charge build-up. Unlike hard disk drives, where the read/write head never touches the disc surface, there is contact between the head and recording medium in a tape system. This results in the build-up of static charge and, should this rise to around 40 volts, results in the destruction of the sensitive read-write head. By using a metal-evaporated tape, the static charge is kept below 5 volts, said Kato. A commercial tape based on the new technology is still some way off. The company has to work on a technology that allows stable recording of high density data on the tape although Sony expects a product based on the system could hit the market sometime in 2003 or 2004.