Chapter 1 · The Complete Computer Architecture

Knowledge Check

5 min read

Try to answer before reading the answers below. Guessing is fine; checking your guess is how you learn.

Quick Review (5 minutes)

  1. What is the difference between RAM and storage?
  2. What does the motherboard do?
  3. Why does the CPU need a chipset?
  4. What is a bus?
  5. What runs in kernel mode vs user mode?
  6. Name three types of buses in a computer
  7. Why is there a privilege boundary between kernel and user mode?
  8. What is firmware?
  9. What does a driver do?
  10. What happens when you press the power button? (in general terms)

ANSWER KEY — DO NOT READ UNTIL YOU'VE ANSWERED

Click to reveal answers

1. RAM vs Storage

Think of RAM as your desk and storage as a filing cabinet.

RAMStorage
SpeedFastSlower
Power offTemporary (loses data when powered off)Permanent (keeps data when powered off)
Used forRunning programs and active dataFiles, programs, OS
CostExpensive per gigabyteCheap per gigabyte
Typical size16 GB is typical500 GB–2 TB is typical

2. What does the motherboard do?

  • Provides the circuit board everything plugs into
  • Routes signals between components
  • Distributes power
  • Contains the chipset (I/O hub)
  • Contains firmware (BIOS/UEFI)
  • Synchronizes everything with a clock

3. Why does the CPU need a chipset?

Because:

  • The CPU can only have a limited number of direct connections
  • The chipset acts as a hub connecting to slower devices
  • It separates fast components (CPU, RAM, GPU) from slower ones (USB, NIC, audio)
  • It manages power distribution and monitoring

4. What is a bus?

A bus is:

  • A pathway for data and signals between components
  • Like a highway: data travels on it from one component to another
  • Examples: system bus (CPU↔RAM), PCIe (for GPUs), USB (for peripherals)

5. User mode vs kernel mode

Kernel mode (Ring 0):

  • Windows kernel runs here
  • Drivers run here
  • Can directly access hardware
  • Can access all memory
  • Trusted, powerful code runs here

User mode (Ring 3):

  • Applications run here
  • Cannot directly access hardware
  • Cannot directly access other applications' memory
  • Must ask the kernel (via system calls) for privileged operations

6. Three types of buses

Any three of:

  • System bus (CPU ↔ RAM)
  • PCIe (GPU, network cards)
  • USB (external devices)
  • SATA (hard drives)
  • NVMe (SSDs)
  • Thunderbolt (high-speed external)

7. Why the privilege boundary?

  • Security: Applications can't access each other's memory or hardware directly
  • Stability: One buggy application can't crash the entire OS
  • Isolation: Different users' data is kept apart
  • Control: The OS enforces permissions and resource limits

8. What is firmware?

  • Code stored on a chip that runs before the OS
  • Non-volatile (doesn't lose data when powered off)
  • The first code to run when you power on
  • Controls hardware start-up (initialization)
  • Examples: BIOS, UEFI, GPU firmware

9. What does a driver do?

  • Provides an interface between the OS and a hardware device
  • Translates OS commands into hardware commands
  • Handles interrupts from hardware
  • Manages DMA (direct memory access)
  • Provides APIs for applications to use the device

10. What happens when you press the power button?

General sequence:

  1. PSU turns on
  2. Motherboard powers up
  3. Firmware (BIOS/UEFI) starts
  4. Hardware initialization (POST, the start-up self-check)
  5. Bootloader runs
  6. Windows kernel loads
  7. Drivers load
  8. Services start
  9. Login screen appears

(We'll cover this in detail in Chapter 6)

UNDERSTANDING QUESTIONS

These need longer answers. Write a few sentences for each.

1. Explain Why A Computer Needs Multiple "Layers" (Firmware, OS, Drivers, Applications)

Don't just list the layers. Explain the purpose of each layer and why we can't just have applications talk directly to hardware.

2. Explain The Relationship Between The CPU, RAM, And Storage

Why is RAM necessary? Why don't we just use storage directly? What's the trade-off?

3. Explain What Would Happen If The Chipset Failed

What components would stop working? Why? What would be the symptom?

4. Explain How A Keyboard Input Reaches Your Application

Trace the path from you pressing a key to the application receiving that input. What hardware and software components are involved?

5. Explain Why Drivers Sometimes Need To Be Updated

What changes? Why can't you just use the same driver forever?

SCENARIO QUESTIONS (Troubleshooting)

Scenario 1: "My USB Device Isn't Recognized"

What components might be involved?
Where would you start troubleshooting?
What would you check?

Scenario 2: "My Computer Is Very Slow"

Is this a CPU issue, RAM issue, or storage issue?
How could you tell?
What information would you need?

Scenario 3: "I Upgraded My RAM But Windows Still Says I Only Have 4 GB"

What could cause this?
Would you suspect hardware or software?
Where would you check?

Scenario 4: "My Network Doesn't Work"

What components are involved?
What software is involved?
Where would you start troubleshooting?

Scenario 5: "My Computer Won't Turn On"

What are 5 possible component failures?
How would you diagnose each?

INTERVIEW QUESTIONS

These are questions a technical interviewer might ask. Answer them out loud, in plain words.

1. Explain the purpose of the motherboard chipset.

2. Why does modern hardware use multiple buses (PCIe, USB, SATA) instead of one bus for everything?

3. Explain the trade-off between SRAM (cache) and DRAM (RAM) in terms of speed and capacity.

4. Why do we need firmware separate from the operating system?

5. Explain what "abstraction" means in the context of computer architecture.

PRACTICAL TASK

Task: Document Your Computer's Hardware

Open System Information and Device Manager (instructions in the Practical Lab).

Create a document with:

  1. CPU Information

    • Model
    • Cores/threads
    • Frequency
    • Manufacturer (Intel or AMD)

  2. Memory

    • Total RAM
    • Type (DDR4, DDR5, etc. if visible)

  3. Storage

    • Number of drives
    • Type (SSD, HDD, or both)
    • Capacity of each
    • Connection type (SATA, NVMe, etc. if visible)

  4. Network

    • Adapter type (Ethernet, Wi-Fi, or both)
    • Model

  5. Display

    • Resolution
    • Refresh rate (if visible)
    • GPU (integrated or discrete)

  6. USB Controllers

    • How many USB controllers?
    • What USB versions (2.0, 3.0, 3.1)?

Why This Matters

  • You're now reading your computer's hardware specifications like an engineer
  • This is the first step in troubleshooting any computer problem
  • You understand what you have and can make informed decisions