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ing, and in user interface design. ? Contemporary humanputer interaction models, whether mandline, menudriven, or GUIbased, are inappropriate and inadequate to the ubiquitous case. Core concept ? This suggests that the natural interaction paradigm appropriate to a fully robust ubiquitous puting has yet to emerge although there is also recognition in the field that in many ways we are already living in an ubip world. ? Contemporary devices that lend some support to this latter idea include mobile phones, digital audio players, radiofrequency identification tags, GPS, and interactive whiteboards. Core concept ? Mark Weiser proposed three basic forms for ubiquitous system devices, see also Smart device: tabs, pads and boards. – Tabs: wearable centimetre sized devices – Pads: handheld decimetresized devices – Boards: metre sized interactive display devices. Core concept ? These three forms proposed by Weiser are characterized by being macrosized, having a planar form and on incorporating visual output displays. ? If we relax each of these three characteristics we can expand this range into a much more diverse and potentially more useful range of Ubiquitous Computing devices. Core concept ? Hence, three additional forms for ubiquitous systems have been proposed: [4] –Dust: miniaturized devices can be without visual output displays, ., Micro Elect