Chorded keyboards

While reading up on the T9 text entry method on Wikipedia, I came across "chorded keyboards".
Even though it happens quite often, I keep being startled when I work on an idea for some time only to stumble upon someone who had the same idea.
Not that I am disappointed about not being the first. I am amazed how people come up with similar stuff.
Back to chorded keyboards..
Well, the naming is probably the reason I didn't find it, before. Still seems strange. Says the guy not playing any instrument.. And not that Ahto is any better.
The guy who introduced chorded keyboards was named Douglas Engelbart. In his initial design he used five keys valued 1,2,4,8 and 16. So powers of two.. Much like I tried in version 1.0, Engelbart used binary counting to go through the alphabet. Later designs (of course) tried different layouts (-;
​There even seems to be some studies on chorded keyboards being faster than QWERTY keyboards. Will have to look into that.