Amiga OS Architecture: Lessons from a Legacy System

This article delves into the Amiga OS API and ABI, focusing on its unique direct-call shared library approach, eliminating runtime linking. This is achieved by calling a table of branch instructions at a known location within the library. Exec.library, always at the same address, provides functions to get the addresses of other libraries' tables. This ABI is language-agnostic and functions even with modern memory protection. Amiga OS is further praised for its efficient kernel, messaging system, and Intuition windowing system, which enables asynchronous event handling, avoiding the program freezes common in modern systems. The design principles of Amiga OS remain relevant today.