Comparing operating systems¶

Practical 2.1 comparing-operating-systems-annex.pdf · PDF

Your aunt calls. Her laptop is from 2015, it still runs Windows 10, and a pop-up keeps telling her to upgrade. She asks you: "You study computers. Which one do I install?"

"The one I like" is not an answer a technician gives. In the OS census you counted a dozen systems in one classroom. Each one exists because it is the right answer for some person on some machine. This page gives you a method to find that answer — the same four questions every time — and a few commands to check whether a real PC can run a system at all.

The family map¶

Start from what you already know: every OS has a kernel, and kernels come in designs (OS architecture). Group the systems by kernel and the map draws itself:

flowchart TB
    subgraph NT ["Windows NT kernel"]
        W11["Windows 11"]
        WS["Windows Server"]
    end
    subgraph XNU ["XNU kernel: Apple hardware only"]
        MAC["macOS"]
        IOS["iOS / iPadOS"]
    end
    subgraph LNX ["Linux kernel"]
        DEB["<b>Debian</b><br>made by volunteers"] -->|"Ubuntu is<br>built from Debian"| UBU["<b>Ubuntu</b><br>made by Canonical"]
        FED["Fedora"]
        AND["Android"]
    end

A distribution (or distro) is a complete operating system built around the Linux kernel: the kernel plus the tools, a way to install software and usually a desktop, put together and kept up to date by a project or a company.

Debian is made by volunteers. Ubuntu is made by the company Canonical and is itself built from Debian. That is why what you learn on one works on the other — handy, because you will install both in this unit.

The four questions¶

To compare two systems, always ask the same four things — and write them as the columns of a table:

The rule for question 1: official page or it does not count. Not a blog, not a forum, not an AI answer. Requirements change between versions, and only the maker's page is the source of truth. In Practical 2.1 you fill the comparison table from these pages:

• Windows 11 — microsoft.com/windows/windows-11-specifications
• Ubuntu 26.04 LTS — documentation.ubuntu.com/release-notes/26.04, section Requirements and compatibility
• Debian 13 — the installation guide for amd64 on debian.org, section 3.4 Meeting Minimum Hardware Requirements
• macOS 27 — support.apple.com, the list of compatible computers

Three things trip people up when reading them:

• Debian's table has two rows, No desktop and With desktop. Pick the one that matches what you will install.
• Apple gives a list of compatible Macs, not gigabytes. macOS is licensed only for Apple hardware — and version 27 only for Macs with Apple silicon.
• Minimum means "it installs and starts", not "it runs well". Comfortable use needs more.

Why updates matter¶

Question 2 includes something people forget: how long the system gets updates. Windows 10 support ended on 14 October 2025. Those PCs still start, but they receive no more security fixes. Every hole found from that day on stays open.

An operating system without updates is a house whose lock everybody has the key to. "It still works" is not the same as "it is still safe".

Many of those PCs cannot move to Windows 11 because of one line in its requirements. You will find which one in Practical 2.1.

Can this PC run it?¶

Reading a requirements list is half the job. The other half is knowing your own machine. On the classroom PC (Ubuntu), open a terminal and collect the facts:

LC_ALL=C lscpu | grep -E "Architecture|Model name|^CPU\(s\)"
free -h
df -h /
ls /sys/firmware/efi
cat /sys/class/tpm/tpm0/tpm_version_major

What each line tells you:

LC_ALL=C at the start forces English labels. If your PC is set to Spanish or Catalan, lscpu translates them and grep finds nothing.

A TPM (Trusted Platform Module) is a small security chip — or a function inside the CPU — that keeps secret keys safe, for example the key that encrypts your disk.

Systems without a desk¶

Everything so far is about the computer on your desk. Most operating systems in the world live somewhere else:

An embedded system is a computer built into another device to do one fixed job. Remember from Unit 1: a router is a computer — and it has an OS too.

Some embedded systems have a stricter promise to keep:

A real-time operating system (RTOS) guarantees an answer within a fixed time, always.

An airbag that opens "usually fast" is useless. It must open within a guaranteed number of milliseconds, every time. That guarantee — not raw speed — is what makes a system real-time.

Three facts to remember the range:

• Supercomputers: since November 2017, all of the 500 fastest computers in the world run Linux.
• Mars: NASA's rovers have used a real-time system from the company Wind River.
• Ingenuity, the small helicopter that flew on Mars in 2021, ran Linux: the first time Linux flew on another planet.

Making a recommendation¶

Back to your aunt. A good recommendation names one system and gives two reasons, each taken from the four questions. Look at how it works for a different client:

Notice what is missing: "because it is better". Better for what, on which machine, for whom — that is the comparison. In Practical 2.1 you do the same for four clients, including a laptop very much like your aunt's.

Key takeaways¶

• Group systems by kernel: Windows NT (Windows), XNU (Apple, only on Apple hardware), Linux (the distributions and Android).
• A distribution is a complete OS built around the Linux kernel; Ubuntu (Canonical) is built from Debian (volunteers).
• Compare with four questions: requirements, characteristics (including updates), field of use, licence. Requirements come from the official page only.
• Windows 10 has had no security fixes since 14 October 2025: "it works" is not "it is safe".
• Check a PC with lscpu, free -h, df -h /, /sys/firmware/efi (UEFI) and the TPM version.
• Beyond the desk: servers, mobile, embedded systems and RTOS, which guarantee a response time.

Quick check¶

Next: the fourth question deserves a page of its own — Software licences.