Table of Contents
How the board in front of you (Raspberry Pi) is a computer
The following diagram shows an abstract view of the board does.
The largest chip on the board is what is known as the SoC or System-on-a-chip, which is listed on the diagram as ‘CPU/GPU’ and is the brains of the Pi. The system-on-a-chip has that name because there are a number of ‘support chips’, and other electronics that are required for a CPU/GPU to communicate with the outside world. The other large chip on the topside of the Pi is the USB controller. On the bottom of the board are the wireless (shielded), RAM, and MicroSD slot.
The I/O (input/output) on the Pi is mostly in the SoC with access to the pins on the chip exposed with the double row of header pins that are on the board. In addition there is an internal USB hub that is used to connect the wired network connection and USB ports. The wireless is embedded into the Pi and does not go through the USB hub. (On most computers the wired connection is also more directly connected, through a faster connection know as a bus (a bus is collection of connections that work together).
A USB hub is a device that allows multiple USB devices (including other USB hubs) to connect to a single USB controller.
Another important piece of the Pi is the RAM — that is the scratchpad the CPU/GPU use while the Pi is powered on (but is not persistent).
And finally, connected through more I/O is the micro SD card, which provides persistent storage, which means what is on it continues to exist when the Pi is turned off, even if it is removed from the Pi.