Bill Buxton's Notes
First released in 2002, the FrogPad is an interesting 1-handed keyboard having 20 keys. The way that one can get the full alphabet in upper and lower case, as well as all of the numbers, punctuation and special characters is not to rely on one-key-per-character. Hence, the FrogPad is a chord keyboard â€“ but one that has more keys than the 5 â€“ 8 seen on most. The result is that entering a character requires only 2 keys to be pressed, at most. The higher number of 1-key characters and the restriction to two key chords means that higher typing speeds are more likely possible on this device than chord keyboards with fewer keys but more complex, and more frequent chords â€“ all things being equal (such as quality of design of the key mappings).
There are two layouts available for the device: one for typing with the left hand, the other for typing with the right. Each is a mirror-image of the other, which reflects the mirror-image layout of the hands.
The interesting question that this provokes is this: should a right-handed person use the right or the left hand version of the device? As always, the correct answer is, "It depends." In this case, one of the prime factors is this: do you want to use it in conjunction with a mouse? If so, then generally, you would likely be best to adopt a FrogPad that is designed for use by your non-mouse hand (most typically, your non-dominant hand). The good news is, due to the mirror-image mapping of the keys on the left and right hand keyboards, moving from one to the other should require only little adjustment.
Of course, each instance of "likely", "typically", "generally" and "should" indicates something that could be tested and quantified, which is my way of providing a concrete example illustrating how formal user studies can shed light on design questions.