A [Raspberry Pi](https://www.ampheo.com/c/raspberry-pi/raspberry-pi-boards) works like a complete computer on a small board: when you power it, it loads an operating system from storage (usually a microSD), starts Linux, and then you can run programs—plus it exposes hardware pins (GPIO) so it can control electronics. ![its-a-computer](https://hackmd.io/_uploads/S13t5Fq7Ze.jpg) **1) What’s inside a Raspberry Pi** * [SoC](https://www.ampheo.com/c/system-on-chip-soc) ([System-on-Chip](https://www.ampheo.com/c/system-on-chip-soc)): the “brain” (CPU + GPU + memory controller + I/O). On most models it’s an ARM-based [Broadcom](https://www.ampheo.com/manufacturer/broadcom) SoC. * RAM: working memory. * Storage: usually microSD (some models support booting from USB or NVMe via adapters). * Power management: regulates 5V input into the voltages the chip needs. * I/O: USB ports, HDMI, Wi-Fi/Bluetooth (on many models), Ethernet (on many), and GPIO header. **2) What happens when you power it on (boot process)** 1. Power applied (typically 5V via USB). 2. The SoC runs a tiny built-in boot ROM. 3. The Pi reads boot files from the boot device (often microSD): firmware + bootloader. 4. It loads the Linux kernel and device settings. 5. Linux starts services and shows the desktop or a login prompt. 6. You run apps, scripts, servers, etc. **3) Why it’s popular** * It runs a full OS (usually Raspberry Pi OS, a Linux distro), so it can do “PC tasks”: * web browsing, coding, media playback, servers * It also behaves like an embedded controller because of GPIO: * read buttons/[sensors](https://www.ampheo.com/c/sensors), drive LEDs/[relays](https://www.onzuu.com/category/relays)/[motors](https://www.onzuu.com/category/motors-actuators-solenoids-and-drivers) (with proper driver circuits) **4) How the GPIO fits in** The GPIO pins are direct connections to the SoC’s I/O: * Digital input/output (3.3V logic) * Buses: I²C, SPI, UART, PWM * You control them via libraries in Python/C or via Linux interfaces. Important: GPIO is 3.3V only—feeding 5V into a GPIO pin can damage it. **5) Typical “how you use it” patterns** * Desktop mini-PC (light computing) * Server (Pi-hole, web server, Home Assistant, NAS-lite) * Robotics / automation (camera + control) * IoT gateway (collect [sensor](https://www.ampheoelec.de/c/sensors) data, send to cloud) * Education (Linux + programming + electronics)