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How does a PC work - How a computer works explained simply

The PC - how it all began

How does a PC work

First, let's take a look back into the past!

The first home computer, the predecessor of today's PC, was introduced by the IBM company in 1981. This personal computer (PC) did not yet have a hard disk, but two floppy disk drives. Due to the drop in prices for electronic components and cheaper replicas from other companies, the PC began its triumphant advance in German households. In 2007, 73 % of all German households had a PC. In 2018, it was already 90 %. (Source: www.destatis.de)

But what was there before? 

Ramon Llull

The Spaniard Ramon Llull constructed a "logical machine" as early as the 13th century, which can be regarded as the first construction of the later computer. At that time, however, it was unthinkable to technically implement and build such a machine. Therefore, his elaboration has unfortunately been forgotten again in the course of the centuries. In 1623, Wilhelm Schickard invented a "four-species machine", a mechanical calculator that contained many gears derived from the then developing art of watchmaking. Johannes Kepler, a famous physicist at the time, used Wilhelm Schickard's machine for astronomical calculations.

Ramon Llull

Image by Ramon Llull, source: Wikipedia

Gottfried Leibniz

1703 invented Gottfried Leibniz invented the dual system - the binary number system - which only formed the basis for computer computing over 200 years later. Modern digital computers only know the state "current" or "no current". Exactly these states can be represented with the dual system. The first machines that could read punched cards were built in the 19th century. 

Herrmann Hollerith

Towards the end of the 19th century, in 1890, a census was conducted in the USA. A punch card machine developed by Herrmann Hollerith was used. In 1935, IBM built the first computer that was "fed" with punched cards and could perform one multiplication per second. 

At that time, punched cards contained the programmes and calculation instructions that told the computer what to calculate. In this sense, punched cards were the predecessors of floppy disks and the USB sticks that are almost exclusively used today. 

Modern times

The punch card computers, which were about the size of 10 huge freezers put together, were followed by magnetic tape computers. These were seen as an enormous relief, as large magnetic tapes could now store the data and computing instructions.

Gradually, electronic components became smaller and smaller and the first microchips were developed. These became the basis for building ever faster home computers. We will take a closer look at the exact structure of a PC in the coming sections.

How does a PC work - the first IBM PC

the first IBM PC, source: Wikipedia

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How does a PC work?

Schematic structure of a PC

Personal computer, exploded

Schematic structure of a PC, source Wikipedia

How does a PC work? To understand this, you should be able to name all the components of a PC!

The components of a modern PC (microcomputer in a desktop case), pictured:

  1. Monitor
  2. Main board
  3. Main processor
  4. Working memory
  5. Plug-in cards
  6. Power supply unit
  7. Optical drive
  8. Hard disk
  9. Computer mouse
  10. Keyboard

Further down this page you will find an online exercise to check if you know all the components of a PC!

 

The inner workings of a PC in more detail

The following picture shows the inside of a PC

Components computer worksheet

Desktop PC open

A PC case opened:

  1. Power supply unit
  2. Power supply cable
  3. Processor with cooling
  4. Hard disk
  5. Data cable for connecting drives to the motherboard
  6. Slots for additional modules

 

Actually, the inside of the PC is quite empty. We see a power supply unit, a motherboard with many slots, some data drives and cables. On the main board there is a fan. Underneath this fan is the core of the computer, the processor. The "brain" of the PC gets so hot that it has to be cooled.

Many cables branch off from the power supply unit, because every device and the motherboard are supplied with power from the power supply unit. In order for the data to be exchanged between the processor and the various drives (hard disk, CD/DVD drive, etc.), wide data cables - like a data highway - must be laid starting from the motherboard.

Fan on processor
Fan on a processor,
currently the processors are much bigger!
Intel Pentium processor (1993)
Intel Pentium processor from 1993.
Current processors are significantly larger!
Intel Pentium processor back panel
Back of the Pentium processor
PC memory modules RAM
Memory modules RAM,
left for notebook, right for PC
Hard disk HDD SSD
Hard disks, HDD for PC and notebook

Components for your own computer

If you want to assemble a PC yourself, you will definitely need the following components:

  • a housing with power supply unit

  • a motherboard and a modern fast processor

  • a fast graphics card, if not installed on the motherboard

  • Sufficient main memory that is matched to the board

  • At least one hard disk

  • a DVD drive, possibly with burning function

  • several cables to connect the drives to the motherboard

Peripherals

Not to be forgotten are the peripherals. These are components that are located outside the central unit of a computer.

These include, for example:

  • Modem

  • Monitor ;

  • Printer 

  • Scanner 

  • Memory card reader

  • Keyboard

  • Trackball

  • USB hub (distributor)

  • USB stick

  • Webcam

 

Monitor, keyboard and mouse are absolutely necessary to operate a PC. The monitor is called an output device, whereas the keyboard and mouse are input devices.

Computers explained for children
Important peripherals
for a computer
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Important notes:

  • If the graphics card is permanently installed on a board, it is slower and less powerful than a dedicated graphics card.

  • If you buy the processor in addition to the mainboard, you must always think about a cooling module as well!

  • The main memory, the so-called RAM (Random Access Memory), must always fit on the board. 

  • When assembling the components into a PC, it is very easy to destroy the very thin connectors and pins that are attached to the motherboard.

Tip:

To assemble a PC yourself, you should be very familiar with it. If in doubt, buy a fully coordinated configuration with warranty from a dealer.

Components Computer - The Notebook Computer

Notebook Computer Explained for Children

More and more people are opting for a compact computer that can be taken anywhere: the notebook computer.

Advantages:

A notebook combines many functions in one device that are performed by different components in a PC:

  • Screen

  • Calculation unit

  • Keyboard

  • Touchpad instead of a mouse

In addition to these advantages, a notebook speaks for itself:

  • Easy transport

  • Low space requirement

Disadvantages of a notebook computer compared to a PC

Of course, a notebook also has disadvantages compared to a PC. These clearly lie in the compact design and all the associated limitations:

  • The processor must be cooled particularly well. That is why notebook computers are usually somewhat less powerful so that they do not consume so much power.

  • The graphics card is usually not as powerful because it is always attached to the motherboard of the notebook.

  • A notebook is only conditionally suitable for "game lovers". Games always need the fastest graphics card!

  • There is no possibility to insert further components into a free slot.

  • The built-in hard disk has a smaller capacity because there is not as much space in the housing.

  • With the same performance, a notebook is always more expensive than a comparable PC.

The individual components of a notebook are becoming more and more powerful, so these disadvantages are disappearing more and more. The advantages of the compact design come to the fore and more notebooks are now sold than desktop PCs.

 
Notebook computer
Notebook computer
Notebook computer from the inside
Notebook computer
Interior view
Computer Explanation Notebook
Enlargement:
Fan above processor
and main memory (RAM)

The BIOS and the operating system

How does a PC work - Nothing works without an operating system!

The BIOS

PC is first of all "stupid". When it is switched on, it must know exactly what to do. It must first check whether all connections are present, whether a screen and a keyboard and mouse are connected. These tasks are taken over by the BIOS - the Basic Input Output System.

The BIOS is permanently contained on a chip that is located on the motherboard. The BIOS also checks which drives are connected and on which drive the operating system should be searched. No PC can function without an operating system. The operating system configures the PC, manages the memory, integrates the input and output devices (keyboard, mouse, hard disks, etc.) and then allows us to work with the PC and run other programmes.

Each type of computer has its own operating systems, which are specially adapted to the microchips and the particular construction. Every mainframe computer, supercomputer, pocket computer and not to forget, every mobile phone has its own operating system.

After the BIOS has checked the state of the PC and found an operating system, it is loaded into the PC's main memory.

The operating system

The operating system now recognises all other components such as graphics cards, card readers, CD drives etc. and ensures that they can be used. To do this, the operating system loads so-called drivers. The drivers are specific software programmes that the operating system needs to "talk" to other devices and use them.

How does a PC work without BIOS?

 

Computer explains BIOS for children
Bios chip on a motherboard
No PC works without BIOS!

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Want to know more about BIOS and operating system?

 

Known operating systems are:

  • Windows from the Microsoft company

  • MAC OS for Apple notebooks and computers

  • Linux, Ubuntu, etc., free software based on Unix

  • iOS, iPad OS and Android for mobile phones, smartphones and tablet computers

    It is important for us to know that you cannot work with a PC without an operating system.

Mobile devices - tablet computers and smartphones

Tablet and smartphone computer explained for children
Tablets and smartphones are now
almost as powerful as PCs

How does a PC work - But there are also smartphones and tablet computers!

The requirements for a computer have changed greatly over the last twenty years. Society has become more mobile and this has also created a need for mobile devices. The new devices have about 10,000 times the storage capacity and many times the computing power of the first PCs and can perform many tasks that were previously only conceivable on larger devices:

  • E-mail communication

  • Internet access

  • Games

  • Writing shorter texts

  • Listen to music

  • Picture gallery, digital photo album

 

Apps or applications

Programmes that are installed on a mobile device are called APPs, the abbreviation for application or app.

The number of apps available for the devices is constantly increasing and ranges from free programmes financed by advertising to expensive special applications for certain professions such as doctors.

Tablet computers are a complete replacement for the PC or notebook when they offer all the required functions of a larger computer. With technical development, tablets are becoming more and more powerful, so that this limit is disappearing. The rate of tablet ownership is estimated by market researchers to exceed 20 % of all households in the coming years. Almost 86 % of all users work with their tablet exclusively at home, only 40 % need it for work. The most common uses are video games, using social networks via the internet, reading newspapers, researching and watching TV shows.

Disadvantages:

Tablet computers are rather unsuitable for the following applications, as they lack the performance as well as the ease of use provided by input devices such as keyboard and mouse:

  • Extensive text input, e.g. for book authors

  • Image processing that requires very high graphics performance

  • Office functions with connection to printers and other output devices (scanner, fax, etc.)

The original function of the phone is fading more and more into the background with smartphones. The owner of a smartphone spends most of his time on the mobile internet and listening to music. In the meantime, smartphones have the same functionality as tablet computers. Only the screen is slightly smaller.

 

Computer explanation for dummies
Be careful when using
the smartphone!

Discussion - Do you know your way around?

A friend invites you to an online game via a social network. However, you have to download an app and install it on your smartphone. Everything works fine and you play the new game with enthusiasm. You're online everywhere you go and soon you're climbing up the hit list of the best players. Only one thing annoys you. Strangely enough, for a short time now you've been getting emails with strange offers and even phone calls from companies who want to sell you something. And the worst is yet to come. During your last summer holiday, your home was burgled and many expensive items were stolen. Is it all connected somehow?

What could be the cause of these events?

Discuss the situation with your friends and classmates.


Picture credits on this page:

© Okea - Fotolia.com, © Scanrail - Fotolia.com, http://commons.wikimedia.org/wiki/ File:IBM_PC_5150.jpg, http://commons.wikimedia.org/wiki/File:Ramon_Llull.jpg, http:// commons.wikimedia.org/wiki/File:Personal_computer,_exploded.svg, © photosoup - Fotolia. com, © Onidji - Fotolia.com, © Arcady - Fotolia.com, PC interior: Jörg Christmann