Define and classify by generations

An embedded system is a dedicated computer system (processor, memory, I/O) built into a larger device to perform one specific function, often in real time.

Classification by generation

1. First generation: built around 8-bit microprocessors (e.g. 8085, Z80) and 4-bit microcontrollers. The hardware circuits were simple and the firmware was written in assembly language. Examples: digital telephone keypads, stepper motor control units.
2. Second generation: 16-bit microprocessors and 8-bit or 16-bit microcontrollers. Their instruction sets were more complex and powerful than those of the first generation, and some systems included an embedded operating system. Examples: data acquisition systems, SCADA systems.
3. Third generation: 32-bit microprocessors and 16-bit microcontrollers, with the arrival of domain-specific processors such as DSPs and application-specific integrated circuits (ASICs). Instruction sets became more powerful, pipelining was used, and dedicated embedded real-time operating systems appeared. Examples: robotics, media, industrial process control, networking.
4. Fourth generation: system-on-chip (SoC), reconfigurable processors and multi-core processors, with high-performance real-time embedded operating systems. Examples: smartphones, mobile internet devices (MIDs).
5. Next generation (present and future): even more powerful SoCs and multi-core processors, very low power, wireless connectivity, networked IoT devices and AI at the edge. Examples: wearables, smart homes, autonomous vehicles.