Toshiba has poured cold water on Transmeta's claims about the low power consumption and heat generation of its Crusoe chip, despite the fact that it is an investor in the chip startup.

Transmeta claims that Crusoe increases battery life in lightweight notebooks to eight hours, more than doubling the two to four hours provided by equivalent Intel chips. It also claims that notebooks running the chips are quieter as Crusoe does not need noisy cooling fans.

However, Steve Crawley, Toshiba UK's product marketing manager, said that the company had no current plans to introduce Crusoe into future Toshiba products.

"[Crusoe] does give a reasonable increase in battery life, but nothing like Transmeta's publicity is claiming. The back light consumes a lot of power - one quarter of the power is used pushing light out. Realistically, in sub-notebooks it gives a 30 to 40 per cent increase in battery life," he said.

He added that Toshiba currently has prototypes of ultra-light notebooks with eight hour battery life using Intel rather than Transmeta chips. "This can be done with a standard Intel box," he said.

"It is an interesting technology but at the moment we are not convinced it offers the user what is required. It will be very interesting to see if it can add any significant value to the end user in terms of battery life or thinness," he said.

But Transmeta contested Toshiba's claim, saying its eight hour notebook was too heavy to be classed as an ultra-light device.

Ed McKernan, director of marketing at Transmeta, said: "Toshiba's eight hour battery life today requires a 2.2lbs battery attached to the base of their Portege 3440 and 3480 notebooks. This means that [it] ends up weighing 5.61lbs - which is outside the ultra-light category of 2lbs to 4lbs."

"Transmeta's Crusoe processor is today being designed into products that will arrive in the fourth quarter and first quarter [of next year] with all day battery life. In addition, it is providing relief to original equipment manufacturers and designers that must deal with the heat caused by the hot processors - even Intel's 'one watt' processor," he added.

Toshiba agreed a licensing deal with Transmeta in February 1998, following the signing of a similar deal with IBM in December 1997. The deals, which gave Transmeta access to IBM and Toshiba technology in return for the right to use Transmeta technology in x86 products, provided the startup with much of its early revenue.

Transmeta subsequently reacquired the rights granted to IBM and Toshiba to manufacture and market x86 compatible products. It agreed to pay IBM a total of $33m over the next four years and issued 600,000 shares of common stock to Toshiba. IBM and Toshiba retain a licence to manufacture, market and sell non-x86 compatible products incorporating the licensed technology.