Single page | Applying Computers

1 Used definitions

To understand the operating principles of computer systems we use basic terms:

👤 User — a person or a group of people who interact with a computer to solve their tasks.
💻 Computer — an electronic device (or a related system of several devices) controlled by programs. Depending on the installed programs, its functions change so that it can be a useful tool for the user.
📊 Digital data — any information familiar to us (texts, photographs, music, or video) represented in a “language” the computer understands (binary code). Thanks to this representation, the computer can store, process, and transmit it.
⚙️ Program — a digital tool, a prepared set of commands for the computer. It is used to work with digital data in the way the user needs.
🛠️ Hardware components (“hardware”) — all physical parts (electronics, chips, boards) from which the computer is assembled.

2 Computers

The choice of device(s) and programs depends on the user’s needs: the requirements are dictated by the tasks that will be performed with them.

When choosing a computer, characteristics may include:

programs;
required component power;
cost of system deployment;
energy consumption and maintenance cost;
form factor;
whether you already have these devices, or component compatibility with existing ones, and so on.

Understanding the task requirements allows better system optimization in terms of resources spent on deployment, use, maintenance, and/or scaling.

Examples of tasks

Internet access — communication, access to public resources, and so on;
work with specialized programs — office file editors (documents, spreadsheets, presentations), work with 3D models, editing video/audio or images, complex mathematical calculations, programming, and so on;
interaction with equipment — peripheral devices (keyboard, mouse, display), network connections, modular hardware components, audio devices, and so on.

Typical examples of a computer

Smartphone, tablet, laptop, PC, router, game console, smartwatch, smart refrigerator, smart vacuum cleaner, 3D printer, video surveillance camera, smart thermometer, and others.

Some kinds of computers are more flexible in the choice of hardware components and programs, while others can be used only in the manufacturer’s device configuration yet provide other advantages.

For example, a PC has a flexible choice of modular powerful components and a wide range of available programs, yet cannot be put in a pocket while powered on like a modern smartphone. At the same time, a smart thermometer that only measures temperature and transmits it is a simpler and cheaper solution for its task. Although both a PC and a smart thermometer perform digital computation, they are designed for different tasks and have different use cases.

3 Programs

Programs make it possible to use a computer’s hardware components to perform the user’s digital operations.

A device’s software consists of several levels. This is necessary for compatibility among various kinds of programs and hardware components. It usually operates on three interrelated levels.

1. Low-level firmware (Firmware)

This is basic program code that is “burned” directly into the computer’s hardware components. It provides initial initialization and direct control of hardware (for example, the motherboard).

Firmware acts as the lowest level of abstraction: it prepares the equipment to hand control over to the operating system, or independently controls the entire operation if the device is simple and has no full-fledged OS (such as an electronic thermometer).

Examples:

mobile devices — Bootloader (usually closed and tightly bound to the components of a specific smartphone);
PCs and laptops — BIOS / UEFI and others.

2. Operating systems (OS)

An OS allocates device resources, manages memory, and creates an environment for running the programs you need as processes. Operating systems are always developed for a specific processor architecture (for example, x86_64 for computers or ARM64 for smartphones).

Which programs you can install — and which are available by default — depends on the chosen OS.

For PCs (x86_64 architecture)

Closed source: Windows, macOS (works only on Apple hardware).
Open source: various Linux and BSD distributions.

For mobile devices (ARM64 architecture)

Closed source: iOS (Apple only).
Open source (base): Android.

3. Application software — specialized programs and apps

Developed and optimized for a specific runtime environment (operating system). This allows developers to create programs for a wide range of devices that support the target OS — from Internet access and messaging to complex work with 3D graphics.

The main differences are defined by installation methods and distribution licenses.

Installation methods: program and app

Functionally they may not differ.

Programs — downloaded manually from official sites as installer files.
Apps — installed through centralized “stores” (App Store, Google Play) that are part of the operating system. This makes installation and updating centralized.

Distribution licenses: closed and open source

Closed source

Developed and funded by private companies. The code is hidden.

Free: Google Chrome browser.
Paid (purchase or subscription): Microsoft Office (documents), Adobe Photoshop (graphics), Autodesk Maya, SolidWorks (3D modeling).

Open source (Open Source)

Developed by communities of engineers and enthusiasts. The code is open to everyone; such programs are typically distributed free of charge. Development is funded by donations, commercial distribution licenses, or paid product support. Openness of the code allows the community to conduct its own security audits.

Examples: LibreWolf (browser), Keepass (password manager), LibreOffice (office tasks), GIMP (raster graphics), Blender and FreeCAD (3D modeling), VirtualBox (virtualization), MySQL (database), Busybox (system utilities), and others.

4 Principles of computer computation

Electrical voltage can be used to transmit digital values.

Abstractly:

there is voltage (higher voltage) = on state = 1;
no voltage (lower voltage) = off state = 0.

This fully fits the mathematical binary numeral system. In it, each digit can be only zero or one, and grows in values as powers of two.

Encoding information

This simple “on/off” principle allows the computer to encode any human-understandable information into digital format, for example:

Text — a character table standard is used (for example, Unicode), where each letter, digit, or emoji has its own unique numeric code, which the computer sees as a set of zeros and ones.
Image — broken into a matrix of pixels. The color of each pixel is encoded by numbers (for example, intensity levels of red, green, and blue — RGB).

Hardware foundation of computation

To operate on arrays of zeros and ones, the computer uses transistors — microscopic electronic switches. They are combined into special chips called logic gates (basic logical operations such as “AND”, “OR”, “NOT”).

To make these computations practically useful, the physical scale of the system must be colossal. Today, tens of billions of transistors are placed on a single silicon die of a few square centimeters.

Any computer program, even the most complex, is decomposed at the hardware level into a giant sequence of such primitive operations on bits.

Performance

A typical modern processor has 8–12 cores and runs at about 4 GHz (4 billion cycles per second). This allows it to execute about 100–200 billion instructions per second (GIPS).

Such speed makes it possible, unnoticed by a human, to perform complex mathematical calculations, smoothly draw graphical interfaces, and instantly transmit data to other computers over the network. The limit of capability is the physical characteristics of the hardware components from which the system is assembled.

5 Principles of network connectivity

Connectivity between computers is possible by means of network protocols.

Large blocks of data are not transmitted as a continuous stream. Using information exchange protocols, they are divided into smaller parts (packets) for transport, and after successful receipt on the target device they are reassembled into the original form.

Similar to the real world, addresses are used for navigation, and specialized network computers are responsible for correct delivery of data between them.

Addressing standards

Every device on the network needs a unique IP address. Today there are two main standards:

IPv4: ~4,294,967,296 addresses
IPv6: ~340,282,366,920,938,463,463,374,607,431,768,211,456 addresses

Such a number of addresses (especially in IPv6) makes it possible to create networks of any scale.

Subnets are dedicated address blocks administered by network computers.

Local subnets operate in reserved private address blocks that by standard cannot be used for global addressing. Examples for IPv4:
- 10.0.0.0/8 (16,777,216 addresses)
- 172.16.0.0/12 (1,048,576 addresses)
- 192.168.0.0/16 (65,536 addresses)
- 127.0.0.0/8
- 169.254.0.0/16
External subnets operate with global, non-reserved addresses and, with correct connectivity, can be reachable from the global Internet.

Typical example: Internet provider and home router

An Internet provider administers a network computer that maintains connectivity with the global Internet. To provide connectivity services to the client, a physical connection is made from the provider’s network computer to the client’s network computer.

When connecting the client’s network computer, a private or public address is configured at the level of the provider’s network computer. This address is used for addressing the client’s traffic to the global network, tracking traffic, and collecting the subscription fee.

The client’s network computer administers its own private subnet and is responsible for addressing traffic from it to the provider’s network computer. Configuration is usually done through a web interface or manufacturer programs.

The provider connects to the WAN (external) port of the client device — typically blue; used by default for routing to global resources.
The user’s private computers connect to LAN ports — typically yellow — or via radio waves (Wi-Fi). Without additional configuration, devices on the private subnet have direct connectivity with one another.

Typical network functions

Routing — providing connectivity between computers by assigned IP addresses. If connectivity is lost along one route, the system can automatically choose another path.
DNS (Domain Name System) — translates machine IP addresses into a human-readable text format. Thanks to DNS you remember google.com, not a numeric address such as 8.8.8.8.
DHCP (Dynamic Host Configuration Protocol) — automatically issues IP addresses to new devices connecting to the network, relieving the user of the need to configure them manually.

6 Virtualization

Virtualization of computing resources makes it possible to run isolated environments on shared physical hardware.

This chapter will be expanded.

7 Designing computers

Technologies offer enormous variability at every stage of creating a system.

7.1. Choosing a computer

It is determined which device (or combination of devices) best matches the user’s task.

One powerful computer vs several specialized ones: sometimes it is more appropriate to distribute the task among several simpler devices than to seek one universal device.

Criteria for choice:

component performance;
form factor (stationary / portable);
energy consumption and power source;
compatibility with devices the user already has;
ability to install modular components;
cost of deployment and subsequent maintenance.

7.2. Strategies for organization and network access

It is determined how the system’s elements will be connected to one another and to the global network.

Network topology — whether all devices are on one local network, or the network needs to be segmented (for example, a separate subnet for peripherals, a separate one for main work devices).
Access type — access only within the LAN, or also remote access from outside (via VPN, port forwarding, or a cloud relay service).
Physical connection — Ethernet (stability), fiber optics, Wi-Fi, and others, depending on task requirements.
Fault tolerance — whether a backup connection is needed (for example, a second Internet provider or a mobile modem) in case the main link is lost.

7.3. Access management

It is determined how the system will distinguish and control user access to computers and third-party services.

Accounts — local (access to the computer’s OS) or third-party services (for example, Gmail or corporate portals).
Authentication — password, access key (passkey), biometrics, or multi-factor authentication (MFA), depending on data sensitivity and tasks.
Access rights distribution — defining roles (administrator / ordinary user) and restrictions by the principle of least privilege.
Access synchronization — a single account for all devices (cloud account or domain network), or independent logins on each device.
Storing authentication means — password managers (local or reliable cloud encryption); physical protection of hardware keys (for example, YubiKey); reliable storage of backup recovery codes.
Effective use of access — SSO to reduce the number of authorizations; secure password autofill; device biometric sensors (Touch ID, Windows Hello) for fast unlocking.

7.4. Designing the necessary programs

It is determined where and how software will be deployed before actual system operation begins.

Placement level — locally on the device, on a dedicated server within the LAN (self-hosted), or remotely in the cloud (SaaS/cloud). The choice depends on performance, data confidentiality, and the need for offline operation.
Runtime compatibility check — match to processor architecture (x86_64, ARM) and OS; emulators or compatibility layers if needed.
Licensing model — Open Source or proprietary software; alignment with budget and tasks (one-time purchase, subscription, or free alternatives).
Templating and deployment automation — preconfigured images (VMs, Docker) or automatic installation scripts to speed up and standardize putting the system into operation.

8 Assembling computers

Assembly is the process of physically combining separate parts (hardware components) into a single working computer.

All computers work by similar principles, but their parts may differ in size, power, and compatibility. The best example of a computer assembled like a construction set is the classic desktop PC.

8.1. Main components and their role

Central processing unit (CPU) — executes all commands and calculations. The more “cores” it has and the higher the frequency, the faster it “thinks.”
Motherboard — a large board to which all other parts connect. It provides communication between them and distributes electrical power.
Random-access memory (RAM) — very fast memory for work right now (for example, open browser tabs). When power is turned off, data from it disappears.
Persistent storage (SSD / HDD) — stores the OS, photographs, games, and programs. Data remains after shutdown. SSDs are faster; HDDs are slower but often hold more.
Graphics card (GPU) — built into the processor (for simple tasks) or a separate powerful part (for complex 3D games or video work).
Power supply unit (PSU) — takes current from the outlet and converts it into safe voltage. It must be powerful enough for the entire system.
Cooling system — fans or liquid cooling that keep the processor and graphics card from overheating.
Case and peripherals — the case securely mounts components; peripherals (mouse, keyboard, monitor) are interaction tools.

8.2. How desktop PC assembly proceeds

Preparation — clean workspace; discharge static electricity (touch metal).
Mounting on the board — install the processor, cooling, and RAM modules.
Installation in the case — screw the motherboard inside the case.
Adding parts — power supply, drives, and graphics card.
Connecting cables — connect components to the power supply and motherboard.
First power-on — self-diagnosis. If the fans spin and text appears on the screen, the PC is ready for software configuration.

8.3. Assembling other types of computers

“As-is” devices (smartphones, smartwatches, laptops) — supplied already assembled. Components are tightly soldered on one board for compactness, lightness, and energy savings. The user only uses the device.
Partially modular devices (for example, 3D printers) — arrive as kits of parts (DIY). The user assembles the mechanical frame, connects motors to the board, and performs mechanical calibration.

9 Configuring computers

This process goes step by step “from the bottom up” — from basic equipment commands to creating a convenient work screen.

9.1. Basic equipment configuration (Firmware / BIOS / UEFI)

This is the very first level. When you press the power button, even before the system itself starts, the motherboard’s basic “firmware” is activated.

Its job is to:

check that all parts are in place;
recognize them;
supply correct power;
tell the computer on which disk the operating system lies, so as to hand control over to it.

9.2. Installing the operating system (OS)

This is deploying the main software environment (for example: Windows, Linux, or macOS).

Installation steps

Memory formatting — a clean drive is divided into parts and prepared for writing files (similar to ruling pages in a new notebook).
Installing drivers — small translator programs. They teach the OS to correctly understand your graphics card, Wi-Fi adapter, or sound card. Without drivers the image may be stretched, and sound may be absent.
Network settings — issuing a unique IP address and configuring a Firewall — your digital “guard” that decides which data from the Internet is safe to let through and which should be blocked.

9.3. Creating a personal space

The final stage — adapting the system to you:

Accounts — creating your profile with a password. For better security it is recommended to have an ordinary account for everyday work and a separate “Administrator” profile for serious changes.
Programs — installing the tools you need: browsers, office suites, messengers, games, and so on.
Convenience — wallpaper, language, text size, and automatic launch of favorite programs.

10 Maintaining computers 🛠️

Even a perfectly assembled system over time accumulates dust, gets clogged with software “junk,” and wears out.

10.1. Physical (hardware) maintenance

Aimed at supporting the condition of the components themselves.

Fighting dust — dust works like a warm blanket. If heatsinks are clogged, the processor overheats and deliberately slows down (throttling). Regular careful cleaning returns speed.
Thermal paste replacement — between the processor and the heatsink a special paste helps transfer heat. Over the years it dries out, so it periodically (once every few years) needs to be renewed.
Modernization (upgrade) — often it is enough to add RAM or replace an HDD with an SSD for the device to work noticeably faster.

10.2. Software maintenance (system hygiene)

Updates — regular installation of OS and program updates. This is like vaccination: developers close security holes and improve performance.
Digital cleaning — deleting temporary files, old downloads, and unused programs. This frees disk space and improves stability.

10.3. Data preservation (backup)

Any physical part will eventually break, or the device may be stolen. Specialists use the golden backup rule “3-2-1”:

make 3 copies of important data;
store them on 2 different media (for example, the computer + an external disk/flash drive);
keep 1 copy outside the home (for example, in reliable cloud storage) in case of physical damage.

10.4. Lifecycle and ecological disposal

When repair or upgrade costs more than a new device, the computer is taken out of service.

Data destruction — simply moving files to the “Recycle Bin” is not enough. Before selling or giving away a computer, the disk must be completely and irreversibly wiped (or the smartphone reset to factory settings).
Recycling (disposal) — electronics and batteries must not be thrown in ordinary trash because they contain harmful substances. Take them to electronic waste (E-waste) collection points, where useful materials are safely extracted.