It’s interesting that Dagmar should bring up Mike’s suggestion that buttons be placed on the back of the PDA. I played around with these ideas about six years ago. Here is a little java applet I made in early March 2003 to visualize how you might arrange the keys on such a device: http://kenperlin.com/handheld (drag your mouse to see it from different angles).
In that device I was going for a QWERTY arrangement, gripped from the two sides in both hands, using the four fingers to type, although you could also put thumb keys on the top. The idea here is that your keypresses are mirrored on the display while you are just learning – until you get good at it, and then you no longer need that help.
I’m kind of amazed that even now (six years later!) there is no commercial product out there that even tries to do a physical keyboard on the back. I couldn’t possibly have been the only one playing with these ideas, even back then.
Hmm, every time I call Mike ‘Mark’ at night he gets angry. 🙂
Maybe a whole keyboard in the back is too much, just think about eight buttons and you do not really need to move your fingers.
Mike just said even the eight buttons for Braille wont work, because the people don’t want to learn. But than again they use cell phones with funny navigations, so it might be still worth a try. 😉
Please forgive me Mike, it was very late when I wrote that, and I had just spent a lovely day with my dear brother Mark. So in an odd way it was a compliment. 🙂 I’ve corrected his name in the post, so nobody reading this Blog will perpetuate my error.
Mike could be right, but my thinking has evolved since 2003, and my recent work has been more in-line with your thinking, of using a small number of buttons, and yes, Braille indeed seems ideal for this form factor. In fact, that is one of the reasons I wrote the Braille writer learning applet!