Also known as: MCU, microcontroller
A microcontroller (MCU) is a tiny, low-power computer on a single chip that combines a processor, memory, and input/output, dedicated to controlling one device or task.1
Overview
Unlike a full computer, a microcontroller has no operating system: your code runs bare metal as the device’s firmware. It boots in milliseconds and can run for years on a small battery, working with only kilobytes of RAM and a modest amount of on-chip flash. That frugality is the point — an MCU does one job reliably and cheaply.
How it differs from a single-board computer
A single-board computer like a Raspberry Pi runs a real OS and behaves like a small PC; a microcontroller does not. MCUs are programmed in C, C++, and sometimes Rust or MicroPython, then flashed onto the chip. Popular families include Arduino boards and the Wi-Fi-equipped ESP32, and most expose their pins as GPIO for wiring up sensors and radios. These are the small radios that populate the airwaves GopherTrunk listens to, even though they are far too small to run GopherTrunk itself.
Sources
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Microcontroller — Wikipedia, on the single-chip design and embedded role of MCUs. ↩