The four were announced by Microsoft which constitutes a fifth manufacturer with its Surface tablet which comes in both x86 and ARM versions.
Toshiba had intended to produce an ARM-based machine but decided not to when, so it says, it couldn't get the components - although this could just be an excuse for getting windy - like HP which dropped an RT-based tablet project.
Asustek will use an ARM-based Nvidia processor.
Asked what he expected the performance of ARM-based Windows 8 computers would be like, ARM CEO Warren East replies: "There are hints in the Microsoft Surface. There are two versions, one ARM, one x86. The ARM version weighed two thirds less, it was two thirds of the thickness and it didn't have cooling vents. It suggests to me that it's a lower power design."
Microsoft has stated that products usung RT will be light and thin with a long battery life.