AbstractMachine is a minimal, modularized, and machine-independent abstraction layer of the computer hardware: * physical memory and direct execution (The "Turing Machine"); * basic model for input and output devices (I/O Extension); * interrupt/exception and processor context management (Context Extension); * virtual memory and protection (Virtual Memory Extension); * multiprocessing (Multiprocessing Extension). CONTACTS Bug reports and suggestions go to Yanyan Jiang (jyy@nju.edu.cn) and Zihao Yu (yuzihao@ict.ac.cn).