Q.Draw the block diagram of a computer system. Briefly write about the functionality of each component.

                 +---------------------------------------+
                 |         Central Processing Unit       |
  +-------+      |  +--------------+   +-------------+   |      +--------+
  | Input | ---> |  | Control Unit |   |     ALU     |   | ---> | Output |
  | Unit  |      |  +--------------+   +-------------+   |      | Unit   |
  +-------+      |             [ Registers ]             |      +--------+
                 +-------------------^-------------------+
                                     |
                          +----------v-----------+
                          |  Primary Memory      |
                          |  (RAM / ROM)         |
                          +----------^-----------+
                                     |
                          +----------v-----------+
                          |  Secondary Storage   |
                          +----------------------+

• Input unit (keyboard, mouse, scanner): takes data/instructions from the user into the computer. …

The block diagram

                 +---------------------------------------+
                 |     Central Processing Unit (CPU)     |
  +-------+      |  +--------------+   +-------------+   |      +--------+
  | Input | ---> |  | Control Unit |   |     ALU     |   | ---> | Output |
  | Unit  |      |  |     (CU)     |   |             |   |      | Unit   |
  +-------+      |  +--------------+   +-------------+   |      +--------+
                 |             [ Registers ]             |
                 +-------------------^-------------------+
                                     |   (system bus)
                          +----------v-----------+
                          |   Primary Memory     |
                          |    (RAM  /  ROM)     |
                          +----------^-----------+
                                     |
                          +----------v-----------+
                          |  Secondary Storage   |
                          |  (HDD / SSD / DVD)   |
                          +----------------------+

As a node-and-arrow list: Input Unit → CPU; CPU ↔ Primary Memory; Primary Memory ↔ Secondary Storage; CPU → Output Unit — all transfers riding on the system bus.

Functionality of each component

• Input unit — the computer's receiving end. Devices such as the keyboard, mouse, scanner and microphone accept data and instructions from the user and convert them into a form the computer can process (binary).
• Central Processing Unit (CPU) — the brain of the computer, which processes both data and instructions. Inside it:
  • Control Unit (CU): the supervisor — it fetches instructions from memory, decodes them, and directs/coordinates the activities of all other units (when to read input, what the ALU should do, where results go).
  • Arithmetic Logic Unit (ALU): performs all arithmetic operations (add, subtract, multiply, divide) and logical/comparison operations (greater than, equal, AND/OR). …