Activity: Computer Organization & I/O

Understanding system architecture & input/output devices

Grade XI • Computer Science ⏱️ ~25 min
🎯 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
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
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
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
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

Next: take the interactive assessment to test your knowledge!