Below is a set of detailed, hierarchical notes that summarize the transcript. Each major heading is phrased as a question to stimulate learning, and every example (and analogy) mentioned in the lecture has been woven into the notes.
---
# 1. Intro to Operating Systems – Why Do We Need an OS to Manage Scarce System Resources?
- **What are the core responsibilities of an operating system?**
- **Resource Management:**
- Every computer system has a set of scarce resources (CPU, memory, storage, network, etc.) that must be allocated efficiently.
- Similar to economic principles, limited resources have high demand; hence, the OS must judiciously schedule and manage these resources.
- **What is the role of the Kernel, and how is it different from a full operating system (or distro)?**
- **Kernel as the Core Component:**
- The kernel is responsible for low-level tasks: managing hardware (drivers, CPU scheduling, memory management, etc.) and exposing a clean API.
- **Example & Analogy:**
- One can compile and run the Linux kernel “raw” (as seen when the creator or enthusiasts customize it) rather than using a full distribution.
- Distributions such as Ubuntu, Arch Linux, or Raspberry Pi images add user-friendly tooling (GUI, command-line tools like `top`, etc.) on top of the kernel.
- **Clear Separation:**
- The OS is more than just the kernel—it is a collection of tools that pipe into the core kernel for easier use by average users.
---
# 2. CPU Resources – What Makes the CPU a Critical and Complex Resource?
- **Why is the CPU considered the heart of execution?**
- **Execution Hub:**
- The CPU is where actual instruction execution happens.
- Its effectiveness is amplified by the placement of frequently accessed data as close as possible (e.g., residing in registers and caches).
- **How do caches and CPU cores optimize speed?**
- **Cache Levels and Their Speeds:**
- **L1 Cache:** The closest and fastest (nanoseconds latency).
- **L2 & L3 Caches:** Progressively slower; L3 cache is often shared among several cores.
- **Multi-Core Challenges:**
- With multiple cores, processes can be scheduled concurrently.
- **Cache Coherence Issue:**
- *Example:* One core may load a variable into its cache and another core may load the same variable independently. If one updates it, the change must be propagated (or caches must be invalidated) to maintain consistency.
- **What about CPU instruction sets and architecture differences?**
- **Machine-Level Instructions:**
- Each CPU has specific machine code instructions. Compiled languages must target a specific CPU since the byte sets differ.
- **RISC vs. CISC:**
- **ARM Processors (RISC):**
- They use a reduced instruction set, making them fast and power-efficient (ideal for IoT devices and phones).
- **Intel Processors (CISC):**
- They execute more complex instructions that may require multiple clock cycles.
---
# 3. Memory and Virtual Memory – How Does the OS Manage Fast, Yet Volatile, Memory?
- **Why is memory (RAM) key to process execution?**
- **Volatility and Speed:**
- Memory, specifically RAM, is volatile—it loses all stored data when power is lost.
- It is “random access,” meaning any location can be quickly fetched compared to sequential devices like magnetic tapes or disk spindles.
- **Real-World Example:**
- Modern chips like Apple’s M1 and M2 bring memory even closer to the CPU to minimize access delays.
- **What is virtual memory, and why do we use it?**
- **Abstraction Over Physical Memory:**
- Virtual memory hides the complexity of physical memory management.
- It maps virtual addresses to physical ones with the help of page tables.
- **How It Works:**
- *Example:* If a process is inactive, its memory pages can be swapped out to disk. When the process accesses that virtual address again, a “page fault” occurs, and the OS fetches the data back from disk.
- **Analogy:** Similar to a front-end requesting data from a backend server; one call may be acceptable, but many calls in a loop can add up and slow performance.
---
# 4. Storage: HDDs Versus SSDs – How Are Data and Files Persistently Managed?
- **What types of storage do we use, and how do they differ?**
- **Magnetic Hard Disk Drives (HDD):**
- Use physical components (read heads, platters, cylinders, sectors) and offer tremendous longevity.
- **Solid State Drives (SSD):**
- Use NAND flash memory organized as pages and blocks.
- **Key Consideration:** SSDs have limitations like “program erase cycles” and require writing a whole page even for a minor change.
- **How is data organized on these storage devices?**
- **Logical Block Addressing (LBA):**
- The file system abstracts raw storage as an array of fixed-size blocks.
- *Example:* A file (e.g., `Test.txt`) with only three bytes still consumes an entire block (say 4000 bytes) because storage is allocated in fixed block sizes.
- **What role does the File System play?**
- **Abstraction for Usability:**
- File systems offer a friendly interface (files, directories) over the raw block device.
- **Examples of File Systems:**
- **Linux:** ext4 (default), btrfs, tmpfs (in-memory file system)
- **Windows:** NTFS, and historically FAT32 (which was used for cross-platform compatibility).
---
# 5. Network Resources – How Does the OS Enable Communication Over Networks?
- **Why is network management integrated into the OS?**
- **Interfacing with the Physical World:**
- The OS must manage data coming from various network interfaces (Ethernet, fiber optic cables, etc.).
- Network interface controllers (NICs) have hardware that communicates via drivers, which the kernel abstracts.
- **How are network data and protocols handled?**
- **Layered Communication:**
- Physical signals are converted into bits, which are then formed into layer 2 frames, layer 3 packets, and so on.
- **TCP/IP Stack:**
- **Example:**
- TCP (Transmission Control Protocol), developed in 1981, is a foundational and long-standing protocol implemented entirely within the OS for reliable communication between hosts.
---
# 6. Processes and Programs – What Is the Difference Between a Program and a Process?
- **How do we differentiate a program from a process?**
- **Program vs. Process:**
- **Program:** A static, compiled executable (e.g., Postgres, MySQL binaries) stored on disk.
- **Process:** An active instance of a program running in memory; it includes the machine code, data structures, stack, and heap.
- **Execution File Formats:**
- **Windows:** Portable Executable (PE)
- **Linux:** Executable and Linkable Format (ELF)
- **Mac:** Mach-O
- **How does the OS manage processes?**
- **Process Scheduling:**
- The kernel schedules processes (and threads within processes) onto available CPU cores.
- **Memory Allocation:**
- Each process has a virtual address space divided into a “user space” for application data and a “kernel space” for system operations.
- **Example in Practice:**
- Task Manager on Windows or the `top` command on Linux serves as a tool that accesses kernel APIs to list and manage these processes.
---
# 7. System Calls and Mode Switching – How Is Privileged Work Safely Performed?
- **What are system calls, and why are they necessary?**
- **Bridging User and Kernel:**
- System calls are the interface between user applications (running in user space) and the kernel (running in kernel space).
- They allow operations such as reading from disk, allocating memory, or writing to a file.
- **Why is mode switching considered expensive?**
- **Costly Context Switching:**
- Every system call triggers a switch from user mode to kernel mode, requiring the saving and restoring of registers and other critical data.
- **Analogy:**
- Think of it like a DMV counter where the current in-process request is paused to attend to another urgent request. Too many switches (or “interrupts”) can slow down the system.
---
# 8. Device Drivers and Interrupts – How Do We Bridge Hardware and Software?
- **What role do device drivers play in the OS ecosystem?**
- **Smooth Hardware Operations:**
- Device drivers are specialized software modules that reside in the kernel, managing communication with hardware devices (e.g., keyboard, network card).
- **How do interrupts function in managing devices?**
- **Interrupt Service Routines (ISR):**
- When an event occurs (such as a keystroke from the keyboard), an interrupt is sent to the CPU.
- The CPU immediately suspends its current work to execute an ISR to handle the event.
- **Example & Analogy:**
- A keyboard press causes an interrupt; the CPU fetches the character from the keyboard buffer.
- This is likened to a DMV where the person currently being served must momentarily step aside to let the next person obtain service.
- **Additional Note on Shared Memory:**
- Some advanced features, like I/O rings, use shared memory between user and kernel space for performance gains—but this can raise security concerns (as noted with Google’s temporary disablement of such features due to potential vulnerabilities).
---
# 9. Abstraction Layers and APIs – How Do Simplified Interfaces Hide Complex Hardware Details?
- **Why are abstraction layers essential in OS design?**
- **Simplification of Complexity:**
- Lower-level hardware details (such as specific CPU instructions, raw block addresses) are hidden behind a uniform API.
- This abstraction allows developers to write applications without worrying about the intricate specifics of the underlying hardware.
- **What are some examples of these abstractions?**
- **File System Abstraction:**
- Instead of managing raw disk blocks or cylinder/sector layouts, the OS presents files and directories.
- The file system internally manages block allocation, mapping file data to physical sectors on disk.
- **Network Stack Abstraction:**
- The raw network packets and electrical signals are abstracted into higher-level entities like TCP/IP packets.
- **Kernel API Abstraction in General:**
- Every hardware interaction (CPU instructions, memory access, network communication) is mediated by well-defined APIs from the kernel.
---
# 10. Summary and Reflection – What Are the Key Takeaways from This Overview?
- **Core Responsibilities of the Kernel:**
- Manages scarce resources (CPU, memory, storage, network) and enforces security through separation of user and kernel spaces.
- Provides APIs (via system calls) that allow higher-level tools (desktop environments, command-line utilities) to function efficiently.
- **Balancing Abstraction and Performance:**
- Abstraction layers simplify programming and user interaction but may introduce performance overheads.
- Real-world trade-offs are evident in every component—from block-level storage (even small files occupying full blocks) to costly mode switches during system calls.
- **Integration Across Multiple Domains:**
- Operating systems integrate and coordinate diverse areas: hardware control (drivers and interrupts), efficient scheduling (CPU and memory), persistent storage (file systems), and inter-device communication (network protocols).
- The evolution of these subsystems (e.g., moving from cylinder-head addressing to logical block addressing, from monolithic kernels to modular and secure designs) reflects the continuous balance between usability and system efficiency.
---
These structured notes capture all the details mentioned in the transcript—from foundational concepts like kernel vs. OS to deeper dives into CPUs, memory, storage, processes, and networking. The question-based headers are designed to encourage critical thinking and make each section conducive to learning. Enjoy your study, and feel free to refer back to these notes as you explore operating systems further!
Below is an extended set of hierarchical notes that builds on the previous summary. These new sections answer your follow-up questions in a structured, question-driven format to promote clear understanding.
---
## 1. Kernel vs. CPU
- **Q: How is the Kernel different from the CPU?**
- **Kernel:**
- A software-based core of an operating system that manages resources (CPU, memory, storage, network) and provides an interface (APIs/system calls) for programs to interact with the hardware.
- It is responsible for scheduling processes, managing memory (including virtual memory), handling device drivers, and security isolation between user and kernel spaces.
- **CPU:**
- A physical hardware component that executes instructions.
- It performs computations based on machine code provided by compiled programs or interpreted runtime environments.
- The CPU itself does not know about high-level concepts like files or processes; it simply executes instructions as directed by the OS (via the kernel).
---
## 2. CPU Session Questions
- **Q: Is it true that each CPU has its own dedicated L1, L2, and L3 cache?**
- **Answer:**
- **L1 Cache:** Typically, each core has its own dedicated L1 cache (often split into instruction and data caches) with the fastest access times (measured in nanoseconds).
- **L2 Cache:** Usually dedicated per core as well, though sometimes it can be shared between a pair of cores depending on the architecture.
- **L3 Cache:** Often shared among all cores on the same CPU die, serving as a larger but slightly slower cache to coordinate data between cores.
- **Note:** Cache organization can vary depending on the CPU architecture (e.g., Intel vs. AMD vs. ARM).
- **Q: How is CPU different from Processor?**
- **Answer:**
- The terms "CPU" and "processor" are frequently used interchangeably.
- **CPU:** Traditionally refers to the central processing unit—the main hardware component that executes instructions.
- **Processor:** Can refer to the entire chip, which may consist of multiple cores (each being an individual processing unit). In modern usage, saying a "processor" often implies a multi-core CPU.
- **Q: What does it mean when a computer has 4 cores? Does it mean it has 4 CPUs?**
- **Answer:**
- A 4-core computer has a single CPU chip containing 4 independent cores.
- Each core can execute its own set of instructions concurrently, allowing for parallelism.
- It does not mean there are four separate physical CPU chips; rather, it is one multi-core processor.
- **Q: What does it mean when we say "compiled languages must target a specific CPU since the byte sets differ"?**
- **Answer:**
- **Compiled Languages:** When you compile code (using C, C++, Rust, etc.), the compiler translates your high-level code into machine code instructions tailored to a specific CPU architecture (Instruction Set Architecture or ISA).
- **Instruction Sets:** Different CPUs (e.g., Intel’s x86 vs. ARM) have different machine code instructions. So a binary compiled for one architecture might not run on another if the underlying instructions differ.
- **Q: What is clock speed?**
- **Answer:**
- **Clock Speed:** Refers to the frequency at which a CPU’s internal clock operates, typically measured in gigahertz (GHz).
- It denotes the number of cycles the CPU can execute per second, determining how many instructions can be processed in a given time period.
- Sometimes misconstrued (e.g., “click speed” may be a typo), but the correct term is **clock speed**.
---
## 3. Memory Session Questions
- **Q: Is memory (RAM) further away from CPU caches? And what’s even further is virtual memory because it needs to be swapped from disk to memory?**
- **Answer:**
- **Hierarchy Overview:**
- **CPU Caches (L1, L2, L3):** These are extremely fast and very close to the CPU cores (sometimes even on the same die) but are small in size.
- **RAM (Main Memory):** Larger and slower than caches; it holds the currently active working set of data and programs.
- **Virtual Memory:** An abstraction that uses disk storage (swap space/page file) to extend the apparent amount of physical RAM. Accessing virtual memory is much slower because it involves disk I/O.
- **Q: Is virtual memory actually the memory stored on disk, just that there are memory pages swapped to the disk?**
- **Answer:**
- **Virtual Memory Concept:**
- It is an abstraction that allows systems to use disk space to simulate additional RAM when the physical memory is insufficient.
- The operating system manages this by swapping out less frequently used memory pages from RAM to disk and vice versa during a page fault.
- Although those swapped pages reside on disk temporarily, virtual memory itself is not “disk memory” but rather a mechanism to extend and manage physical memory efficiently.
---
## 4. Storage Session Questions
- **Q: How is NAS different from a file system or storage?**
- **Answer:**
- **NAS (Network Attached Storage):**
- A dedicated storage device connected to a network that provides file-level data access to multiple clients.
- It typically contains its own file system, which is used to manage and organize stored data.
- **File System/Storage (on a local machine):**
- Refers to the method and data structures an operating system uses to control how data is stored and retrieved on a physical storage medium (HDD/SSD).
- While a NAS uses a file system to manage data, it is distinguished by its network connectivity and ability to share files among devices.
- **Q: Is it true that you can map a NAS to a certain folder/directory?**
- **Answer:**
- Yes, many operating systems allow you to map or mount a NAS share to a local folder or drive letter.
- This mapping enables the NAS to appear as part of your local file system so that you can access and manage remote files as if they were stored locally.
- **Q: How is NAS different from SMB (Server Message Block)?**
- **Answer:**
- **NAS:**
- Is a complete storage system that connects to a network, offering shared storage resources to multiple devices.
- **SMB:**
- Is a network file sharing protocol (primarily used in Windows environments) that facilitates communication for file, printer, and other resource sharing over a network.
- **Relationship:**
- A NAS device can use SMB (among other protocols like NFS or AFP) to share its storage resources. In this sense, SMB is a method by which the NAS makes its managed file system accessible over the network.
---
These extended points integrate seamlessly with the previous notes and provide a clear, cognitive, and hierarchical structure for each concept. This format encourages an incremental understanding—from the low-level details of hardware (CPU, memory, caches) to the higher-level abstractions (virtual memory, file systems, network storage). Enjoy using these detailed notes to reinforce and further your understanding of operating systems and the underlying hardware-software interplay!
Below is an extended set of hierarchical notes that answers your follow-up questions in a structured, question-driven format. These notes build on the previous discussion and provide deeper insights for CPU, Memory, and Storage topics.
---
# 1. CPU
## 1.1. How Are Cores, CPUs, and Processors Related?
- **Q: How is a Core different from a CPU? Are they referring to the same thing? How is it different from a Processor?**
- **Core:**
- A core is an individual processing unit within a CPU that can independently execute instructions.
- Modern CPUs often contain multiple cores, each capable of handling its own stream of instructions.
- **CPU (Central Processing Unit):**
- Refers to the physical chip that contains one or more cores along with caches (L1, L2, L3) and other supporting circuitry.
- It is the main computing component that runs the operating system and applications.
- **Processor:**
- The term “processor” is often used interchangeably with “CPU.”
- In modern terminology, “processor” usually implies the entire chip which includes multiple cores.
- **Summary:**
- A CPU (or processor) is the physical chip. A core is a single execution unit inside that chip capable of independently processing instructions.
## 1.2. Machine Code Instructions and Instruction Sets
- **Q: Is a machine code instruction the same as an instruction set?**
- **Answer:**
- **Machine Code Instruction:**
- It is the binary representation of a single operation that the CPU can execute.
- An example would be the binary code for an addition or memory load instruction.
- **Instruction Set (ISA):**
- The instruction set architecture is the defined collection of all machine code instructions that a CPU can execute.
- It lays out the rules, formats, and operations available.
- **Relation:**
- Each machine code instruction is one element of the instruction set. The ISA is the complete “menu” of instructions, while each instruction is one “dish” on that menu.
## 1.3. Compiled Languages Versus Scripting Languages
- **Q: When compiling code (using C, C++, Rust, etc.), the compiler translates code into machine code for a specific ISA. But what about scripting languages such as Python?**
- **Compiled Languages:**
- The compiler translates source code into machine code instructions that directly run on the CPU under a given ISA (for example, x86, ARM).
- This process creates binaries that are optimized for that hardware.
- **Scripting Languages (e.g., Python):**
- **Interpretation:**
- Python code is usually interpreted. The Python interpreter (often implemented in C) reads and executes Python bytecode.
- **Bytecode:**
- The Python source code is first compiled into an intermediate bytecode, which is then executed by the Python Virtual Machine (PVM).
- **Just-In-Time (JIT) Compilation:**
- Some implementations (like PyPy) use JIT compilers to compile Python code into machine code at runtime for performance benefits.
- **Key Point:**
- Unlike compiled languages that produce standalone binaries for a specific architecture, scripting languages run on a runtime environment that abstracts the underlying hardware differences.
## 1.4. What is Clock Speed?
- **Q: What is clock speed?**
- **Answer:**
- **Clock Speed:**
- The clock speed is the frequency at which a CPU’s internal clock oscillates, measured in GHz (gigahertz).
- It indicates how many cycles per second the CPU can execute.
- **Importance:**
- A higher clock speed means more cycles per second, resulting in potentially faster execution of instructions.
- However, overall performance also depends on factors like the number of cores, cache sizes, and CPU architecture.
---
# 2. Memory
## 2.1. Volatility of Memory and Virtual Memory
- **Q: Is it true that memory/virtual memory will be gone as soon as the machine restarts?**
- **Answer:**
- **Physical Memory (RAM):**
- RAM is volatile memory. It loses all its stored data when the machine powers off or restarts.
- **Virtual Memory:**
- Virtual memory is an abstraction that allows the system to use disk storage (swap space or page file) to extend physical RAM.
- Even though parts of virtual memory reside on disk temporarily, the “active” memory (the pages in RAM) is lost on a restart.
## 2.2. Memory Versus Disk
- **Q: Is memory stored on disk? Is a hard disk called “disk”? Are disks the same as what’s used for storage such as SSDs/HDDs?**
- **Answer:**
- **Memory (RAM):**
- RAM is a separate, volatile form of storage that is much faster than disks and is used for temporary storage of active data.
- **Disk:**
- The term “disk” commonly refers to the physical storage medium used for long-term data persistence. It can be a traditional Hard Disk Drive (HDD) or a Solid State Drive (SSD), even though SSDs do not have spinning disks.
- **Difference:**
- **RAM** is used for active operations (temporary and volatile).
- **Disks (HDD/SSD)** are used for persistent storage (data remains across power cycles).
## 2.3. File Systems, Mounts, and OS Relations
- **Q: Why do certain Linux systems show multiple file systems when I type the `df` command?**
- **Answer:**
- Linux systems can mount multiple file systems, which may include:
- **Primary Root File System:** The main file system (e.g., `/`).
- **Additional Partitions:** Such as `/home`, `/boot`, or swap partitions.
- **Virtual File Systems:** In-memory file systems (like `tmpfs`) or pseudo file systems for devices.
- **Network Shares:** If mounted, these appear as separate file systems.
- **Q: How is a file system/storage different from a mount point when I type `findmnt` in Linux?**
- **Answer:**
- **File System:**
- Refers to the method and data structures (like ext4, NTFS) used by the operating system to organize and store files on a storage device.
- **Mount Point:**
- A mount point is a directory in the Linux file tree where a file system is attached (mounted) so that its contents become accessible.
- **Relationship:**
- The file system exists on the storage device. When it is “mounted,” it is integrated into the overall folder hierarchy and can be viewed via commands like `findmnt` or `df`.
- **Q: How are file systems and mounts related to the OS organization of storage and memory?**
- **Answer:**
- The **Operating System (OS)** manages file systems to provide persistent storage.
- The OS uses **mount points** to integrate different file systems (from disks, NAS, or other devices) into a single, coherent directory tree.
- **Memory (RAM)**, on the other hand, is managed for temporary data and active process execution (using virtual memory mechanisms).
- Although both file systems and memory are managed by the OS, they serve different purposes:
- **RAM** for fast, volatile storage.
- **File systems on disks** for long-term, persistent storage.
## 2.4. Understanding 32-bit vs. 64-bit
- **Q: What does 64/32-bit mean?**
- **Answer:**
- **32-bit vs. 64-bit:**
- These terms usually refer to the size of the CPU's word, registers, and addresses.
- A **32-bit system** can address up to 4 GB of memory (2³² addresses), while a **64-bit system** can address a vastly larger range (2⁶⁴ addresses).
- **Implications:**
- **Performance and Data Handling:**
- 64-bit systems can process larger chunks of data at once.
- **Software Compatibility:**
- Software must be designed for the specific architecture; 64-bit programs require a 64-bit OS and hardware.
---
# 3. Storage
## 3.1. NAS Versus Local File Systems
- **Q: How is NAS (Network Attached Storage) different from a file system or local storage?**
- **Answer:**
- **NAS:**
- It is a dedicated storage device connected to a network, often containing its own operating system and file system.
- It allows multiple clients to access and share files over the network.
- **Local File System/Storage:**
- Refers to the file organization (such as ext4, NTFS) on a storage medium (HDD or SSD) directly attached to a computer.
- **Key Difference:**
- NAS is networked and shared, while a local file system is typically attached directly to a single computer.
## 3.2. Mounting NAS and Related Protocols
- **Q: Is it true that you can map a NAS to a certain folder/directory?**
- **Answer:**
- Yes.
- Operating systems allow you to mount (or map) a NAS share to a local directory or drive letter.
- This makes remote storage appear as if it were a local folder, enabling easy access and management.
- **Q: How is NAS different from SMB (Server Message Block)?**
- **Answer:**
- **NAS:**
- A complete storage device meant for networked file sharing.
- **SMB:**
- A network file sharing protocol primarily used in Windows environments to enable file, printer, and other resource sharing over a network.
- **Relationship:**
- A NAS device often uses SMB (along with other protocols like NFS or AFP) to share its managed storage resources.
- In short, NAS is the hardware/storage system, while SMB is one of the protocols used to access that hardware.
---
# Summary
- **CPU Concepts:**
- **Core vs. CPU:**
- A core is an independent execution unit within a CPU. A CPU (or processor) may contain multiple cores.
- **Machine Code and Instruction Sets:**
- Each machine code instruction is part of an instruction set (ISA). The instruction set defines the available operations on the CPU.
- **Compiled vs. Scripting Languages:**
- Compiled languages generate machine code for a specific ISA, while scripting languages (like Python) use an interpreter or JIT to execute code on a virtual machine layer.
- **Clock Speed:**
- The frequency (in GHz) at which a CPU operates, determining the number of cycles per second.
- **Memory Insights:**
- **Volatility:**
- Both physical RAM and its virtual memory mapping (swapped pages) lose their content on a restart.
- **Memory vs. Disk:**
- RAM is volatile and fast, used for active operations; disks (HDD/SSD) provide persistent storage.
- **File Systems and Mount Points:**
- The OS organizes persistent storage into file systems that get mounted into a unified directory tree.
- **Storage Overview:**
- **NAS vs. Local Systems:**
- NAS devices provide networked storage with their own file systems.
- **Mounting and Protocols:**
- NAS shares can be mounted as local drives using SMB or other protocols, integrating remote storage into your local file hierarchy.
- **64 vs. 32-bit:**
- These indicate the width of the CPU’s registers and addressable memory, affecting performance and memory capacity.
These notes should help clarify the differences and relationships among cores, CPUs, processors, memory types, and storage concepts. Use them as a self-contained guide to deepen your understanding of how these components work together in modern computing systems.