Ndless is a jailbreak and homebrew SDK for TI-Nspire calculators. It enables execution of unsigned ARM-native code and provides a complete development environment including cross-compilation toolchain, system libraries (libndls, libsyscalls), SDL 1.2 port, Lua scripting extensions, and support for multiple calculator models and OS versions (3.x through 6.x). The repository contains exploit-based installers for each OS version, a runtime loader with hooking infrastructure, and a custom executable format (Zehn). The SDK includes sample applications demonstrating graphics, input, particles, networking, and Lua integration. The codebase is heavily based on reverse-engineering of TI's firmware, with hardcoded memory addresses and syscall tables for dozens of OS releases. This is a hybrid project: primarily an application/SDK, but with a significant data/research component in the form of reverse-engineering artifacts (IDA IDC scripts) used to generate syscall mappings.