Dylan Turner's PS-OHK Is a One-Handed Keyboard with an Unusual, Single-Layer Layout
Designed using a four-tier approach to its layout priorities, the PS-OHK is layer-free — but might take a little getting used to.
Electrical engineering graduate and maker Dylan Turner has designed a custom keyboard that enables one-handed typing without the need for multiple modifiers and layers.
"The PS-OHK (pronounced 'psawk' [p͡sɑk̚]) aims to be the ultimate one-handed typing experience with a layout that is easy to get used to," Turner explains of the project, which is named in full the Polymath-Studio One-Handed Keyboard, "but without special modifiers (more or less analogous to a standard key count)."
One-handed keyboards — designed for accessibility purposes, or simply to allow the other hand to remain on a pointing device at all times — are nothing new, but the vast majority used a reduced number of keys compared to a two-handed keyboard. The missing keys are represented in "upper layers," accessible using modifier keys — or, sometimes, through chording multiple other keys together.
The PS-OHK, by contrast, has roughly the same number of keys as a two-handed keyboard. The trick comes in the layout: the user's hand position rests near the most commonly-used keys, requiring stretching only to access those needed less often.
The layout is unusual, and based on a tiered approach. First is what Turner describes as "the most common letters used (home row is R, T, N, and S)," followed by "relationships between sounds (D is common and closest to T and same with L and R). "The shape of a left hand (follows the natural curve of the fingers)" follows next, then finally the layout takes into account a key feature: "practicality (without memorizing obscure layouts, you have access to arrow keys, function keys, etc.)"
More information on the PS-OHK is available on Hackaday.io, while Turner has made the Arduino source code and PCB design files available on GitHub under the reciprocal GNU General Public License 3.