SoC
The Raspberry Pi is a System on a chip (SoC) system, this means that it has a single chip that contains the CPU (Central Processing Unit), GPU (Graphics Processing Unit), RAM (Random Access Memory) and DSP (Digital Signal Processor). The SoC chip used on the Raspberry Pi is the Broadcom BCM2835.
CPU - The CPU has a clock speed of 700 MHz. This is provided from a ARM1176JZF-S core, which is a 32 bit processor and part of the ARM 11 processor family.
RAM - The Raspberry Pi has 256mb of SD RAM, which is shared with the GPU
GPU - The GPU is a Broadcom VideoCore IV, and supports HD video in 1080p
Inputs and Outputs
USB - there are 2 USB 2.0 ports on the board.
Video - There are a number of video outputs on the board:
- HDMI (High Definition Multimedia Interface) - This is a common video connector used by most HD TVs, DVD/BlueRay players and games consoles. To get HD video out of the Raspberry Pi you will need to use this connection.
- Composite RCA - This is an older video connector, it doesn't support HD and gives an analogue output. You will need to use this to connect to older TVs or monitors
- DSI (Display Serial Interface) - This video output is used for direct connection to LCD screens. It's would be used if you were using the Raspberry Pi to building a larger device with a built in screen. Very few consumer screens would use this interface so it's unlikely that a home user would ever connect to this.
Audio - The Raspberry Pi has 2 types of audio output, HDMI and a 3.5mm jack. If you're using HDMI for your video connection then you'll probably be able to use it for audio as well. If not, you can use the standard headphone size 3.5mm jack to plug in computer speakers or similar.
Storage - the Raspberry Pi board doesn't contain any storage devices itself, there is an SD card slot which is used for the Operating System to boot off. If a hard drive is required for extra storage it must be connected via USB.
Power - the board is powered by a 5 volt Micro USB socket, this is becoming a popular power socket and used for charging on a lot mobile phones. There is no on/off switch on the board so as soon as power is connected it will start to boot.
Other - the board also has General Purpose Input Output (GPIO) pins that allow the user to connect other devices such as LEDs, switches and sensors. These can then be controlled programmatically from within the operating system. There are also add-on boards that can connect to the GPIO such as the Gertboard that expand the Raspberry Pi's functionality to allow connection to more devices.