Activity: Computer Organization & I/O

Understanding system architecture & input/output devices

Grade XI • Computer Science ⏱️ ~25 min

Brief Intro — Computer Organization & I/O

A computer system is a complex orchestra of hardware components, from the "brain" of the CPU to the memory that stores your data and the devices that let you interact with the digital world. Understanding how these parts are organized is key to understanding how technology works.

In this activity, you'll explore CPU architecture, the instruction cycle, and the variety of input/output devices and system buses that make computing possible.

🎯 Objectives What you will learn
  • Distinguish computer architecture from computer organization.
  • Describe the functions of CPU, Control Unit, ALU, and registers.
  • Explain the instruction cycle (Fetch → Decode → Execute).
  • Identify various I/O devices and storage types (primary vs secondary).
  • Understand the role of system buses (data, address, control).
🧠 Overview System architecture & I/O

Computer Architecture refers to the design and structure of the computer system as seen by the programmer (instruction set, addressing modes, data types). Computer Organization deals with how the hardware components are implemented and interconnected.

The CPU (Central Processing Unit) consists of three main units:

  • ALU – performs arithmetic and logical operations
  • Control Unit – coordinates and controls the execution of instructions
  • Registers – high-speed temporary storage inside the CPU

The Instruction Cycle follows: Fetch → Decode → Execute.

System Bus is a set of parallel wires connecting major components. It includes Data Bus (carries data), Address Bus (carries memory addresses), and Control Bus (carries control signals).

📌 Part 1 CPU architecture & organization

The Central Processing Unit (CPU) uses its internal components — the ALU, Control Unit, and Registers — to execute instructions with incredible speed.

1. Computer Architecture defines while Computer Organization defines .
Check answer
Architecture = WHAT, Organization = HOW.
2. Which of the following is NOT a main component of the CPU?
Check answer
RAM is not a CPU component. CPU = ALU + Control Unit + Registers.
3. The Control Unit coordinates and controls the .
Check answer
The Control Unit coordinates and controls the execution of instructions.
4. Which register holds the address of the next instruction to be executed?
Check answer
Program Counter (PC) holds the address of the next instruction.
5. Arrange the instruction cycle steps in order:
Check answer
Fetch → Decode → Execute.
📌 Part 2 Memory & storage

Computer memory is organized into a hierarchy, from high-speed internal registers to large-capacity primary and secondary storage.

6. Which is an example of Primary Memory?
Check answer
RAM is primary memory (volatile, directly accessed by CPU).
7. Which type of RAM is faster and does not require periodic refreshing?
Check answer
SRAM (Static RAM) is faster and needs no refreshing. DRAM needs periodic refresh.
8. Match each ROM type with its feature:
PROM →
EPROM →
EEPROM →
Check answer
PROM = one-time programmable, EPROM = erased by UV light, EEPROM = erased electrically.
9. Which cache level is smallest and fastest (inside the CPU core)?
Check answer
L1 cache is smallest and fastest, located inside the CPU core.
10. Arrange these in descending order of speed (fastest → slowest):
Check answer
Registers → Cache → RAM → Hard Disk (fastest to slowest).
📌 Part 3 Input & output devices

I/O devices are the bridges between humans and machines, allowing us to enter data and receive information in various physical and digital formats.

11. Classify each device as Input or Output:
Keyboard →
Monitor →
Scanner →
Printer →
Check answer
Keyboard = Input, Monitor = Output, Scanner = Input, Printer = Output.
12. Which device produces a physical (hard copy) output?
Check answer
Printer produces a hard copy (physical) output. Monitor gives a soft copy.
13. A touchscreen is best classified as:
Check answer
Touchscreen is both input and output — it displays (output) and senses touch (input).
14. Which printer type uses a laser beam to produce output?
Check answer
Laser Printer uses a laser beam — it is a non-impact printer.
📌 Part 4 I/O buses & interfaces

System buses and standard interfaces like USB and HDMI provide the communication paths that allow data to flow smoothly between all system components.

15. Which bus carries memory addresses from the CPU to memory?
Check answer
Address Bus carries memory addresses (uni-directional, CPU → memory).
16. Which transmission method sends one bit at a time over a single wire?
Check answer
Serial transmission sends one bit at a time (e.g., USB). Parallel sends multiple bits simultaneously.
17. USB stands for:
Check answer
Universal Serial Bus.
18. Which interface is commonly used to transmit high-definition audio and video?
Check answer
HDMI (High-Definition Multimedia Interface) transmits both audio and video.
🧪 Challenge Quiz yourself
1. Which component of the CPU performs arithmetic operations?
  • a) Control Unit
  • b) ALU
  • c) Register
  • d) Cache
Show answer
b) ALU (Arithmetic Logic Unit).
2. Which memory type loses its data when the power is turned off?
  • a) ROM
  • b) Flash
  • c) RAM
  • d) Hard Disk
Show answer
c) RAM (Random Access Memory) — volatile memory.
3. Which bus carries memory addresses from the CPU to memory?
  • a) Data Bus
  • b) Address Bus
  • c) Control Bus
  • d) Power Bus
Show answer
b) Address Bus.
4. Which of the following is an output device?
  • a) Scanner
  • b) Keyboard
  • c) Monitor
  • d) Microphone
Show answer
c) Monitor.
✅ Completion checklist

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