Explain computer system with the help of a block diagram. Discuss various components of the computer system with their functions.

A computer system is a complete setup of hardware, software, users and data working together to process information. Hardware alone is useless without software and procedures.

Block diagram:

Input → CPU (ALU + CU + Registers) → Output
          ↕
   Memory (Primary: RAM/ROM + Secondary: SSD/HDD)

Components and functions:

1. Input Unit: Accepts data and instructions. Example: keyboard, mouse, scanner, barcode reader at police check-post. Converts to binary for CPU.

2. Central Processing Unit (CPU):

• ALU: Arithmetic (+, −) and logic (>, =, AND) calculations.
• CU: Fetches/decodes instructions, coordinates all parts; does not process data itself.
• Registers: Ultra-fast tiny storage for current values.

3. Memory:

• Primary: RAM (temporary working space, lost on power off) + ROM/BIOS (startup firmware).
• Secondary: SSD/HDD/pen-drive for permanent citizen records and case files.
• Cache: SRAM between CPU and RAM for speed.

4. Output Unit: Presents result in usable form. Example: monitor (soft copy), printer for FIR copies, speaker.

5. Software, Users, Procedures (system view for 10 marks): System software (Windows/Linux), application (crime-record MS-Access), trained operators and standard procedures complete the system. Failure in any part — e.g. no backup procedure — breaks the whole system even if hardware is fine.