The curious case of the disappearing Polish S
A long-standing keyboard bug caused the Polish letter "Ś" to disappear when typed after certain characters, a problem traced back to a 1980s encoding limitation in the IBM PC's keyboard controller. The issue, which persisted across decades of software and hardware iterations, highlighted how an early design choice remained frozen in firmware, affecting users for over thirty years.
Background
The essay traces a keyboard bug that makes the letter "ś" (Polish s with an acute accent) vanish or become garbled when typed — a problem that has persisted across Windows, macOS, and Linux for decades.
- Polish uses Latin script with diacritics (ą, ć, ę, ł, ń, ó, ś, ź, ż). The "Polish programmers' layout" (common among developers) places these on AltGr key combos; the "Polish typist's layout" uses dedicated keys.
- The bug stems from how dead-key sequences for the acute accent interact with different keyboard layouts and legacy character-encoding assumptions in the input pipeline — an issue silently inherited across operating systems.
- The disappearance of "ś" has long frustrated Polish developers, breaking names, file paths, and common words. The essay uses this single glyph to show how trivial-seeming cross-platform input bugs can survive for 30+ years, revealing deeper architectural mismatches in keyboard handling and Unicode encoding.