🖥 Computer Architecture Overview

🧠 CPU (Central Processing Unit)

The “brain” of the computer — executes instructions and manages system operations.

1️⃣ Control Unit (CU)

• Role: Directs the flow of data and instructions.
• Analogy: CPU’s “CPU” — orchestrates ALU, registers, and memory interactions.

2️⃣ Arithmetic Logic Unit (ALU)

• Role: Performs all arithmetic and logical operations.
• Arithmetic Ops: Add, subtract, multiply, divide.
• Logic Ops: Boolean operations — AND, OR, XOR, NAND, NOT, etc.

3️⃣ Register Array

• Role: Small, ultra‑fast storage inside the CPU.
• Examples:
  • Program Counter (PC): Tracks the next instruction’s address.
  • Instruction Register (IR): Holds the current instruction being executed.
  • General‑Purpose Registers: Temporary data storage.
  • Pointers: Address references for stack, data, or base.

🛣 System Bus

Acts as the information highway between CPU, memory, and peripherals.

• Data Bus: Transfers actual data between components.
• Address Bus: Carries memory addresses for read/write operations.
• Control Bus: Sends control signals (e.g., read/write commands, clock signals).

💾 Memory (RAM)

Temporary working storage for programs and data.

• Basic Unit: 8‑bit byte (2 nibbles).
• Scaling: Larger sizes are multiples of bytes.
• Capacity Measure: Typically in 2ⁿ bytes (binary addressing).
• Common Units:
  • KB: Kilobyte — 10³ bytes (SI standard) or 2¹⁰ bytes (KiB in binary).
  • MB: Megabyte — 10⁶ bytes (SI) or 2²⁰ bytes (MiB).
  • GB: Gigabyte — 10⁹ bytes (SI) or 2³⁰ bytes (GiB).

🔄 CPU–Memory–Bus Interaction Flow

1. CU fetches instruction address from PC via Address Bus.
2. Instruction/data retrieved from RAM via Data Bus.
3. ALU processes data (math or logic).
4. Results stored back in register or memory.