I imagine he'd give almost anything for a machine that could read his mind! It's very clever. but a lot simpler than that. It's a computer running a set of menus which he can control using the equivalent of mouse clicks which he selects using his facial muscles. At its most basic it's predictive text like on a mobile phone. He can select whole words and phrases where required, a bit like soundbites on television - so depending on what question he's asked he might select from 'exactly', 'almost', 'not really', 'not at all'. When he's giving lectures or contributing to a television programme like last night then only the timing has to be "real time". All the rest is a bit like saying "next slide. please" and can be prepared well in advance. From his point of view the machine is an indispensible lifeline, but television and editing makes it look a lot more simple than it is.