[CS Technical Interview 2] Operating Systems That Make Sense

💬 Getting a developer job - coding tests weren't the end of it.

As someone from a non-computer science background, I initially focused only on algorithms and coding tests when preparing for my first developer job. I gained some confidence and passed most coding tests. However, I kept failing at the next hurdle: technical interviews.
What was the problem? It was the lack of CS (Computer Science) knowledge. In interviews, CS fundamentals were considered much more important than algorithms.

🗣 For actual interviews, 'speaking practice' was important.

Even after filling in my CS fundamentals, interviews were still not easy. In an interview at a certain company, I was asked about floating-point numbers. It was content I thought I had read and understood multiple times in books, but I couldn't utter a single word. I painfully realized that passive learning through simply reading and understanding wasn't enough to answer questions in real interviews.

To succeed in interviews, you need not only to accumulate a lot of knowledge but also the ability to explain this knowledge. This 'ability to explain' can only be developed through practice of organizing concepts in just a few sentences and verbalizing them. Through this process, you can also discover what you didn't know precisely. Without sufficient practice, you'll encounter the following problems.

1. Conceptual Confusion Type

❓InterviewerWhat are the characteristics of object-oriented programming?
💬 Candidate The SOLID principles. First, S is..(omitted)...

This is a case of confusing similar concepts.
SOLID is an OOP design principle, and the characteristics of object-oriented programming are abstraction, encapsulation, inheritance, and polymorphism.
The moment you mix up related concepts, the interviewer judges that 'your fundamentals are shaky.'
It's not just a simple mistake, but rather it's read as a signal that your conceptual framework is not solidly established.

2. Lack of Specificity Type

❓Interviewer What are the characteristics of TCP?
💬 Candidate It's a protocol that guarantees reliability.
❓ Interviewer What are the mechanisms that guarantee reliability?
💬 Candidate Uh... well... it makes transmission secure... like that...

This is a case where you only know the What, but lack the How/Why.
You only know the superficial answers and aren't prepared to explain the underlying principles.
TCP establishes communication through connection (3-way handshake), ensures reliability through RDT (sequence numbers, ACK, retransmission, etc.), and maintains quality through flow control and congestion control.
These concepts should be connected as one coherent flow in your mind. Without organizing concepts concretely, you cannot prepare for follow-up questions.

3. Getting tongue-tied with basic questions

❓Interviewer What is HTTP?
💬 Candidate Um... it's for sending and receiving data on the web... something like that...?

It's such a familiar concept, but when asked to explain it in one sentence, the words don't come easily.
Words like request, response, server, and client come to mind, but they don't flow into natural sentences.
This is because we've never practiced explaining from definition to principles in one coherent flow.
This isn't a lack of knowledge, but an absence of structure.

Just knowing is not enough. It only becomes true skill when you can express it in words.

🔥 So I created it. The CS Technical Interview Series That Gets You Talking!

🎯 Recommended for these people

⚡ Lecture Core Kick

💡 Use it like this

💬 Q. The lecture time is short, but will I be able to learn properly?

🖐 Hello! Let me introduce myself! 🙇

I created this course thinking of my past self, who stayed up all night worrying about fundamentals and felt anxious over every single interview question.

I started as a non-CS major and understand better than anyone the thirst for fundamentals (CS knowledge, programming languages, etc.). Through self-study of countless materials and building my own know-how, I eventually graduated from Seoul National University and now work as a 🧑🏻‍💻 Kakao developer.

Since childhood, I've been more confident than anyone in combining and reconstructing various materials to create 'my own consolidated study notes.' This course is precisely that secret notebook born from my 'ultimate self-study know-how' and all my passion and philosophy.

🔥 What makes this course special?

• All of my 'know-how' is included: As a non-CS major, I have fully incorporated my experience and know-how of self-studying CS and programming languages and getting hired at a large corporation. I have put all the methods of how to most efficiently understand complex and abstract concepts and make them your own into this course.

• 'Fundamentals' are key in any development field: Whether you're aiming for game development, AI, web/app development, or any other field, basic computer science knowledge is not optional but essential. This course helps you become a true expert based on solid fundamentals.

• We compete with 'overwhelming quality': I've referenced countless materials including textbooks, famous university lectures, commercial books, and technical interview resources to extract core keywords and reconstruct them in my own unique way. With intuitive diagrams and illustrations, combined with easy explanations infused with my practical experience, I promise to make even complex concepts feel like "Ah, now I get it!"

🚀 Introducing the second lecture [Operating Systems] from the Technical Interview Master Roadmap.

📕 Operating Systems, the Core Key for Developers!

Operating systems are the key to understanding how code written by developers actually runs on hardware, and an essential subject that deals with "how computers work."

• Still confused about the difference between processes and threads❓

• Is it difficult to clearly answer which resources among code/data/stack are shared by threads❓

• Is it difficult to clearly explain what virtual memory is? Deadlock? Deadlock❓

If just seeing the word gives you a headache and you break out in cold sweat when it comes up as an interview question?

This course is designed specifically for those people, providing a clear and comprehensive overview of core operating system concepts through diagrams, flow-based explanations, and practical applications. No more feeling overwhelmed!

🎯 Through this course, you will be able to clearly answer the following questions.

• What does an operating system do in a computer?

  
  → Structurally and clearly explains the definition and functions of the OS, as well as its relationship with hardware.

• How are processes and threads different, and how do their states transition?
  → We'll clearly organize complex concepts including confusing state diagrams, context switching, and multithreading with clean diagrams.

• How does the CPU select processes?
  → Intuitively compare and analyze the principles, advantages, and disadvantages of various CPU scheduling algorithms such as preemptive/non-preemptive, FCFS, SJF, round robin, etc.

• Why does Deadlock occur and how can it be resolved?
  → Learn in-depth through various cases including resource allocation graphs, deadlock occurrence conditions, and avoidance/prevention/detection and recovery methods.

• How does virtual memory work?
  → Explains paging, segmentation, page replacement algorithms, and more with rich visual materials so that even non-majors can understand.

• How are disks managed and scheduled?
  → We clearly organize the various scheduling techniques of disk I/O and the components of file systems by connecting them to actual structures.

📌 At the end of the lecture, a practical interview practice chapter awaits you.

You can now practice answering core questions that frequently appear in technical interviews, such as "What is deadlock?", "Please explain examples of scheduling algorithms", and "Why is virtual memory necessary?", by training yourself to respond fluently in one or two sentences without hesitation.

📖 A curriculum packed with only the essentials

This is the table of contents and key keywords you will learn in this course.

If there are any unfamiliar keywords, make sure to master them thoroughly with this opportunity.

You'll learn this kind of content

👀 Course Preview

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💡 Curious about other interview preparation courses? Check out the roadmap below :)

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