Week 1: Multi-tap, T9, and the keypad that started it
The course's opening argument — that predictive text is a design lineage, not a recent invention, starting with the twelve-key keypad
22 February 2027
Before a phone had a screen worth looking at, it had twelve keys and twenty-six letters to fit onto them, and every letter after the first press of a key was a guess about which word you meant. T9 — “text on 9 keys” — turned that guess into a dictionary lookup: press the keys for the letters, and the phone picks the most likely word those keys could spell. Multi-tap, its clumsier predecessor, made you press a key repeatedly to cycle through its letters. Both are predictive text. Neither looks like what the term calls to mind now.
That’s this week’s argument: “autocomplete” and “predictive text” name a family, not a single interface, and the family is older and stranger than the autocomplete you use today. The keypad is where the family’s central tension shows up in its plainest form — a small, fixed vocabulary of possible inputs, mapped onto an ambiguous signal, resolved by a dictionary that has opinions about what you probably meant. Every later week in this course is a variation on that tension: what the vocabulary is, what the signal is, and whose dictionary gets to decide.
Outline#
- multi-tap versus T9: two ways of solving the same twelve-key problem
- disambiguation: what happens when two words share a keypress sequence
- why this still matters once nobody uses a keypad
- what the lab asks you to build, and why it’s the same problem in miniature
Teaching team
- Priya Nandakumar — convenor