Device drivers are difficult to write and error-prone. They are usually written in C, a fairly low-level language with minimal type safety and little support for device semantics. As a result, they have become a major source of instability in operating system code. This paper presents NDL, a language for device drivers. NDL provides high-level abstractions of device resources and constructs tailored to describing common device driver operations. We show that NDL allows for the coding of a

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... ically correct driver with a code size reduction of more than 50% and a minimal impact on performance.