Computers are incredibly complicated devices yet their general architecture is very simple to understand.
This article provides an analogy to understand how a computer is put together for non-technical people or people interested in understanding how their device works under the hood.
- Welcome to the city
- Places to visit in the city
- Working together
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Welcome to the city
For anyone who’s ever visited a city there are some interesting concepts obviously on display and there are rules governing the city and how it operates.
How computers have evolved very much mirror how a city works but hides inside a black case under your desk in the office or is the laptop in your briefcase. You don’t have to know how the city works you just have to be in it.
In a city you have roads which join buildings together. Those roads have traffic lights which provide timing. In computers these roads are called buses. This road can have many lanes. The more lanes the city has the more traffic can move. Modern 64 bit computers have 64 lanes of traffic where older computers are 32 bit or even back down to 8 bit.
Different roads have different types features such as A roads, B road, national road, motorway, suburban motorway, autobahn. When two different types of road meet you have different types of connections. Connectors allow you to join different roads.
A city has physical space constraints. Space in a city is an issue limiting the number of lanes. This city in a computer is called the motherboard. So the whole city works and operates on the motherboard. Every city has city limits which encase the city. The case is the box that goes around the motherboard to protect it. The image of the motherboard here shows you the confines of the city.
When you have roads in a city you invariably have junctions. The junctions have traffic lights to get the timing right so traffic moves in harmony.
A motherboard has a BIOS or Basic Input Output System and as part of that it has clock which ticks. These ticks, called clock cycles, set up the timing of everything. Everything in the city works in harmony with this clock. This systems has a quartz crystal which also has a battery, so even when your computer turns off it keeps time.
So when you start you have this wonderful mapped area with roads and a traffic light system to make sure everything works together. You have a motherboard with buses and a timing system.
Congratulations you’ve got the idea of the basics of computer architecture.
Now where can we go in our city?
A central government building makes the big decisions for the city. The CPU (Central Processing Unit), often referred to as the processor, is the technical name of the government.
Space in the processor is expensive and fairly limited. A CPU processes and needs to store a lot of paperwork.
A dedicated warehouse for paperwork called RAM or Random Access Memory is available and specially laid out to get information from it to the CPU quickly. You can see in the picture that is very physically close by.
Information shuttles up and down the bus to the CPU regularly as work occurs in the CPU and temporarily stored in RAM. RAM is called primary storage.
All of the city runs on electricity. Power drives the lights, enables the movement of documents and allows the CPU to make decisions but it has one major drawback.
When you turn the power to your computer off the RAM warehouse instantly empties. When RAM suffers a power loss result everything is forgotten hence is called volatile memory. So when you turn the power on to start your city how does it remember anything?
Let us never forget
ROM (Read Only Memory) are computer chips in your device. These chips remember instructions even if you turn the power off. So when you turn your computer on, in the BIOS there is a ROM chip which has instructions on how to turn on the entire city.
When you turn your calculator on it remembers how to do maths if not necessarily the last sum you did.
Every motherboard comes with a manual which most people just chuck in the bin. This manual will tell you exactly what each chip does and where in the city it’s located. Your own personal map to your city. Most manufacturers luckily put theirs online for you to download as well.
How mind boggling impressive is that, in less than 2 seconds when you turn on computers, the power goes through the bus to the BIOS. In the BIOS the ROMs work with the clock to get the whole city awake.
Long term memory
So your computer is only as good as a calculator if it forgets everything every time you turn the power off, so we need another mechanism. It’s more storage space but this time, when you turn the power on or off it stays there. Outside the city down a motorway there is a permanent storage facility. These storage facilities called secondary storage or non-volatile memory can be enormous.
The device called a hard-drive uses magnets rather than electricity to store information this his how it remembers when the power comes back. The problem is that it is located a far way outside the city. It needs to travel down a motorway to get to RAM and then from RAM to the CPU. Imagine this warehouse in another city and there are a lot less lanes connecting to this city. Traffic jams on this route occur frequently and users experience these as slow downs. There’s a traffic jam.
Quick round up
So we have now a city that is useful, can do work and remember what it was doing yesterday. Now we go on to look at some interesting other places in our city.
Places to visit in the city
The art gallery
The Government (CPU) orchestrates everything within the timing of the city. The concept of decentralisation exists in government today.
This practice helps physical space and efficiency by farming work out to different departments which are not in the central government buildings. The government could generate passports but sometimes it’s just easier to farm that out to a department to just look after.
The first of the farming out approach is pictures, more specifically video. The graphics card draws pictures and sends them to the screen, also called the display. The VDU or Visual Display Unit is the techy name for the screen.
So the CPU can farm off work like “draw this on the screen please” to the graphics card so it is freed up to do other work.
As pictures can be a lot of work graphics cards can be sometimes physically bigger than the CPU itself.
The concert hall
If you send pictures to the art gallery it makes sense to have sound sent to a dedicated place for sound.
The sound card is the building dedicated to working out the audio and again freeing up the CPU to get on with other work.
The sound card can handle even newer sound technologies such as Dolby Surround Sound.
The bus and train station
The advent of the Internet has revolutionized not only computing but life.
A modem or Modulator – Demodulator which sounds funky to say, connected your city to the phone line to allow it to chat to other modems. This was very slow. One lane and it started with bicycles only. Engineering companies are designing faster and faster engines to speed up the travel.
A network connection is the fastest connection between computers that were physically close to each and looked after by a network card. A network card is an inter-city train limited by physical tracks, a physical network. Modems are for global communication.
As it is not possible to always have train tracks put down between computers WiFi (Wireless Fidelity) is like a plane system. WiFi can’t transport as much as train weight wise (data speed) but for most journeys and people will work just as well.
The funky other shops
Like any city you can have interesting shops. They all need to connect to the government somehow in the same way that industrial estates emerge around a city.
In 1996 a new set of rules said, if you want to add an industrial estate to the city, no problem but it must stick to these roads.
USB or universal serial bus has a dedicated ROM chip on the motherboard which manages all USB traffic.
Today anything that can be in the city, can also be on the USB. It won’t be as fast as being in the city but it means you can easily add anything to your city.
A keyboard, a mouse, another monitor, a network card or more non-volatile storage all can work on USB.
The laws of the land
OK, we have a city and we interesting places to visit but there are a massive amount of laws and rules that have to be obeyed in the city.
Laws state what can and cannot be done. How does money works? etc. are managed by a set of written down rules. The government (CPU) enforces the law. Where are the rules written down?
The Operating System or OS set the laws of computers. There are different sets of laws for different cities but at the moment there is, like government, a choice of OSes.
Microsoft (Windows), Apple (OS X), Google (Android) and Unix are the major different types of government.
Unix has a variety of types with Linux being the most famous of them. Each have their own pros and cons and will and won’t work with different equipment.
When you use your computer you will see updates. Updates are changes to the law to make sure things work together.
As there are so many combinations of laws and so many different types of shops and what people want to do in their city these companies must bring out new laws.
People don’t like updates as they have to wait or they change the rules of the city. Updates hide the vast complexity of the working city.
When laws don’t work they are changed. New capabilities result in wholly new laws being written. As a result OSes that are always updating.
Different shapes and sizes of computers
Computers come in different shapes and sizes. All computers, personal computers (PCs), desktop, laptop, tablet, gaming consoles, smart phone, smart tv and server all have the same general architecture principals.
In a smart phone the physical space may be a lot smaller and may not contain all the buildings but operates in exactly the same way.
The image on the left is a Samsung Galaxy S9’s motherboard with the CPU and BIOS highlighted.
A server is a different kind of city which has all the same components but focuses on specific city tasks. A server is a city focused on industry whilst a gaming console is a city focused on entertainment and games.
Building your own city
You can go to companies like Komplett and literally buy every part of your city separately, put them all together and build a computer. As parts get old you can replace them with newer ones if the connectors match.
For convenience, companies such as Dell, HP and Lenovo can build your computer for you yet some people really enjoy customising their cities and the amount of combinations of equipment is staggering.
Congratulations you now have all the major terms that describe the architecture of most modern smart devices and how they interact internally.
I’ll be adding more articles of this type to discuss different aspects of cities in the near future, please leave a comment and I’ll keep you updated.