Penti
Here is a truth about typing that Alexander Burger (the creator of PicoLisp) took seriously: ten fingers on a QWERTY keyboard is not the only way – and for some jobs, not the best way. Penti is his five-finger keyboard layout: one hand, five keys, every character reachable by chords.
What it is, in plain words
Penti is a chorded keyboard system. You rest five fingers of one hand on five keys (by default the home row asdfg or hjkl;), and you type by pressing combinations of them – chords – instead of hunting for individual keys. A single finger produces a letter; two or three together produce others; modifiers give digits, symbols and control keys. The whole alphabet, numbers and punctuation fit under one hand.
It’s free software from Burger’s Software Lab, available for Linux (as a small X11/Wayland utility), and there’s a hardware version too. The software sits between your keyboard and the applications, remapping chords on the fly – much like KMonad, but with an entirely different philosophy.
Why it matters
If you ever type with one hand – because the other is on a mouse, holding a book, operating a piece of equipment, or injured – Penti is a complete writing system that doesn’t need a second hand. It’s also a fascinating experiment in information density: with five binary keys you have non-empty chords, and with a few layers that’s more than enough for the Latin alphabet and then some. For someone who lives in PicoLisp, it’s also a piece of the same design culture: do the most with the least.
An everyday analogy: a trumpet
A trumpet has three valves. Press them in combinations and you get every note. The valves don’t map one-to-one onto notes; the chord of valves does. Penti’s five keys are the valves; the characters are the notes. Once your fingers know the chords, typing becomes a kind of playing.
flowchart LR F["5 fingers"] --> C["31 chords + layers"] C --> A["letters, digits, punctuation, controls"] A --> App["any application"]
A hands-on example
The source and documentation live at software-lab.de/penti.html. On Linux with X11 you typically build the small daemon and run it; it grabs the five keys and emits the mapped characters.
A taste of the default mapping (left hand on a s d f g):
| Chord (fingers) | Character |
|---|---|
| 1 (a) | e |
| 2 (s) | t |
| 3 (d) | a |
| 4 (f) | o |
| 5 (g) | i |
| 1+2 | n |
| 1+3 | s |
| 2+3 | h |
| … | … |
| all five | space / enter (by context) |
The common letters get the easiest chords – the same idea that makes Dvorak and Colemak rearrange QWERTY. Digits and punctuation live on a layer reached by a “shift” chord.
Practice tip: don’t try to memorise a chart. Print the reference, cover the keycaps if you like, and type pangrams (the quick brown fox…) until your fingers find the chords without thinking. Expect a few evenings of frustration and then a sudden click – the same learning curve as any new layout.
Pairing Penti with StumpWM or Emacs is natural: one hand types, the other stays on a trackball or on a spare modifier for window management.
Common misconceptions
- “It’s a stenography system.” Stenotype machines for court reporting use many more keys and phonetic chords. Penti is a character-by-character layout that happens to use chords.
- “You need special hardware.” The software remaps an ordinary keyboard. Hardware Penti keyboards exist, but they aren’t required.
- “Five keys can’t be enough.” Combinatorics says otherwise: 31 chords × a couple of layers covers everything a normal keyboard does.
- “It’s faster than QWERTY.” For two-handed touch typing, probably not. For one-handed input, or for a secondary hand, it’s in a different league from hunt-and-peck.
- “It’s only for PicoLisp people.” Burger made it, and it fits that aesthetic, but it works with every X11/Wayland application.