Principles of microprocessor-based systems are covered, including programmers' models of general-purpose microprocessors and microcontrollers, assembly language programming, address maps, memory devices and interfacing, bus timing and standards, input, output interfacing, polling and interrupts and DMA interfaces. Examples are mostly taken from the MC68000 family, although aspects of other microprocessors are discussed. A key aspect is the laboratory work involving an MC68HC11-based target system, where both the hardware and the software drivers for additional subsystems are designed, implemented, and tested.