mruby/c is a lightweight implementation of the mruby bytecode interpreter optimized for microcontrollers with minimal RAM (<40KB). It executes Ruby bytecode generated by the mrbc compiler, supports cooperative multitasking via a built-in scheduler (rrt0), and provides a C API for embedding. The architecture splits into a core VM engine, a configurable memory allocator, a hardware abstraction layer (HAL) for portability across MCU architectures, and built-in class implementations for common Ruby types. The codebase is well-structured and demonstrates strong embedded software engineering practices, with reusable patterns for memory management, value boxing, and platform abstraction. It is not a data/research project; it is a production-quality embedded runtime.