Kimball Brown, Dataquest VP, said: "With the 486, the notebook was about two quarters behind and had been catching up. But with the Pentium it's nearer a year behind, and the lag will stay - it'll never catch up now."

Last year was the year of the desktop Pentium, but the notebook market was dominated by the 486 right into the last quarter, said Brown, who was speaking at Dataquest's PC industry conference in Amsterdam last week.

A key problem is that Pentium has reversed the trend to lower power consumption. "In the 486 cycle the processor was 1.5W and the screen was 5W, now the processor is 7W and the screen is 1.5W," he explained. The MMX multimedia extensions will make things worse, as they will run the processor at full power for longer.

The price premium for notebooks over desktops is also increasing, he said. As a result, their proportion of total PC sales is dropping back.