Just-in-time framework for 8-bit systems

Abstract

This project presents an emulator-integrated instrumentation framework designed to make runtime behaviour easier to observe during development and validation. The primary aim is to capture useful execution information with minimal disruption to normal emulation, allowing developers to inspect what the emulator is doing rather than relying on guesswork when behaviour differs from expectations. The framework is built around lightweight hooks that record instruction flow, memory access activity, and key events such as interrupts, and it exposes this information through a set of interactive tools including tracing, breakpoints, and memory activity visualisation. The framework is implemented as part of a complete emulator, using the Nintendo Entertainment System (NES) as a case study. The NES provides a well-documented and timing-sensitive platform where small behavioural differences are easy to trigger and useful to analyse. To evaluate the effectiveness of the design, the emulator was tested using established NES accuracy test ROM suites and results were compared against a reference emulator (Mesen). The evaluation focuses on whether the emulator reproduces expected behaviour on representative correctness and timing tests, and whether the integrated tooling provides practical value for fault isolation and behavioural inspection. While the project does not aim to replace mature emulators, it prioritises a clear architecture, extensible instrumentation, and practical usability, providing a solid foundation for further experimentation with correctness analysis and future optimisation work, such as performance profiling or dynamic binary translation.