At CoderDojo Athenry, the Hackers spent some time examining the components of a desktop PC and a Raspberry Pi 3+ and a Raspberry Pi Zero.
Even though the Pis are much smaller than a desktop PC, they are functionally equivalent – as we saw, you can plug the Pi into the keyboard, mouse and screen of the desktop PC and use it like one.
We identified the major components of a desktop PC, and saw where each of them appear on the Raspberry Pi also:
- CPU – the central processing unit that does all calculations and processing. All data in a PC gets represented as numbers, so all data processing ends up as calculations.
- GPU – a dedicated processing unit just for graphics, that specialises in multiplying and adding matrices (pixels on a screen are represented as a matrix). Not all PCs have one, but they are important for high-performance graphics.
- RAM – the short-term memory of the computer, used by the CPU to store data.
- Hard Drive – this might be a hard disk drive or a solid-state drive. This is for long-term storage. It holds much more than RAM and the data remains when the PC is powered off, but it is much slower for the CPU to get data from the hard drive than from RAM.
- DVD Drive – not all PCs have this. DVDs or CDs allow permanent storage that can be removed. Some are read-only and some allow reading and writing.
- Motherboard – the circuit board on which everything else is mounted.
- Power Supply – this is built into a desktop PC. For a Pi, this is a 5-volt supply such as a phone charger.
- Networking – ethernet for wired networks and/or wifi for wireless networks.
- Controller chips and connection ports (such USB and HDMI) for peripherals.
- Case – Pis don’t always have these.
We noted that the Pi has a single chip that has its CPU, a basic GPU and up to 1GB of RAM all stacked in layers on top of each other. While its CPU is lower power than a standard PC CPU, it benefits from having a really short distance that data has to travel from RAM to CPU. CPUs run so fast that having electrons travel a few centimetres is a significant delay!
PCs and the Pi also have connections for peripherals, which is anything that can be connected to it, using USB, Bluetooth, HDMI, or other connection types:
- Keyboard and mouse
The Raspberry Pi Zero has micro-USB and micro-HDMI connectors to keep everything as small as possible, and it has wifi only, no ethernet port (though it is possible to get a micro-USB to ethernet adapter).
A couple of members of the group have built their own desktop PCs, which is an impressive feat!