BRLTTY

BRLTTY is the refreshable-braille half of eyes-free Linux — a daemon that reads the text console and writes it to a braille display's dots, maintained by Dave Mielke since 1995, when he wrote it to drive his own Alva display. Where Speakup turns the console into speech, BRLTTY turns it into touch — screen content, cursor tracking, and review commands land on the display's cells in real time, no speech synthesizer required.^[1]

How it works

BRLTTY splits into two halves around a clean seam: a screen driver (the sc family) that reads what the kernel console, a terminal, or a desktop is showing, and display drivers — around fifty of them, covering Alva, Baum, Freedom Scientific, HandyTech, HIMS, HumanWare, Papenmeier, and the rest of the hardware ecosystem — that render it as six- or eight-dot cells. Routing keys on the display map back to console actions: touch a cell and the cursor goes there. Translation tables (its own, plus liblouis-grade support) convert screen text into the right braille code — literary, computer braille, or contracted.^[2]

BrlAPI and the ecosystem

The piece that made BRLTTY infrastructure rather than a program is BrlAPI — a client library that lets other software use the display without owning the hardware. Orca uses it for braille on the GNOME desktop, Fenrir uses it in the console, speech tools route through it — one daemon arbitrates the hardware, everything else is a client. It is the standard braille layer of the eyes-free distros — Slint, Vinux, Adriane Knoppix, Accessible-Coconut all ship it — and its reach extends past Linux entirely: Android, Windows, and DOS builds exist, and the maintainer still ships releases thirty years in.^[3]

See also

• Speakup — the kernel screen reader; BRLTTY's speech counterpart
• Braille n Speak — the 1987 notetaker; the hardware lineage BRLTTY drives
• Kurzweil Reading Machine — where print-to-access began
• Braille · Louis Braille · Abraham Nemeth · Nemeth Braille Code
• Eyes-Free Linux — the handbook chapter that wires all of this together
• The Library — braille codes and translation on the main site