A computer works as a system made up of different units. Each unit has a specific function that helps in converting data → information.
1. Input Unit
Functions
- Accepts data and instructions from the user.
- Converts them into machine-readable form (binary codes).
- Sends the data to the CPU for processing.
Examples
- Keyboard, mouse, scanner, microphone, barcode reader.
👉 Business Use: Entering customer orders, scanning product barcodes in retail.
2. Central Processing Unit (CPU)
Known as the “Brain of the Computer”.
It controls all operations and performs processing tasks.
The CPU has three main components:
(a) Control Unit (CU)
- Directs the flow of data and instructions.
- Controls which operation is to be performed and in what sequence.
- Acts as a “traffic police” for data movement inside the computer.
👉 Example: When a report is generated, CU ensures data moves from storage → ALU → output in correct order.
(b) Arithmetic and Logic Unit (ALU)
- Performs all arithmetic operations: addition, subtraction, multiplication, division.
- Performs logical operations: comparisons (>, <, =).
- Handles decision-making operations based on conditions.
👉 Example: Payroll calculation (adding salaries, deducting taxes) or comparing sales figures.
(c) Registers
- Very small, high-speed storage areas inside CPU.
- Store temporary data, instructions, or results during processing.
👉 Example: When multiplying numbers, intermediate results are stored in registers.
3. Memory / Storage Unit
Divided into Primary (Main) Memory and Secondary Memory.
(a) Primary Memory
- RAM (Random Access Memory): Temporary, volatile memory for active programs and data.
- ROM (Read-Only Memory): Permanent memory storing essential instructions like BIOS.
👉 Example: While preparing a presentation, data in slides is temporarily stored in RAM until saved.
(b) Secondary Memory
- Permanent storage for large data.
- Examples: Hard disk, SSD, Pen drive, Cloud storage.
👉 Business Use: Storing customer databases, employee records, financial statements.
4. Output Unit
Functions
- Displays the processed results to the user.
- Converts machine-readable data into human-readable form.
Examples
- Monitor (soft copy output).
- Printer (hard copy output).
- Speakers, projectors.
👉 Business Use: Printing invoices, showing financial dashboards, presenting reports.
5. Communication Unit (Optional in Modern Systems)
- Handles data transfer between computers over networks.
- Examples: Network Interface Cards (NIC), Wi-Fi modules.
👉 Business Use: Online banking, video conferencing, e-commerce.
Summary Table
| Unit | Functions | Examples |
|---|---|---|
| Input Unit | Accepts and converts data into machine-readable form | Keyboard, scanner |
| Control Unit (CU) | Directs flow of data & instructions | Part of CPU |
| ALU | Performs arithmetic & logical operations | Payroll, comparisons |
| Registers | Stores temporary data & results | CPU internal storage |
| Memory (Primary/Secondary) | Stores programs, data, and results | RAM, ROM, hard disk |
| Output Unit | Presents results in human-readable form | Monitor, printer |
| Communication Unit | Transfers data between systems | NIC, Wi-Fi |