1. Introduction to Computer System
A computer system consists of hardware and software components that work together to accept input, process data, store data, and produce output.
The basic components are: Input Unit, Output Unit, Central Processing Unit (CPU), and Memory Unit.
2. Central Processing Unit (CPU)
The CPU is the brain of the computer. It consists of:
- Arithmetic Logic Unit (ALU): Performs arithmetic and logical operations.
- Control Unit (CU): Directs and coordinates operations.
- Registers: Small, fast memory inside the CPU for temporary data.
3. Memory
| Type | Description | Examples |
|---|---|---|
| Primary Memory | Directly accessible by CPU, volatile | RAM, ROM |
| Secondary Memory | Non-volatile, permanent storage | HDD, SSD, CD, DVD |
| Cache Memory | Very fast, between CPU and RAM | L1, L2, L3 cache |
RAM (Random Access Memory) is volatile (data lost on power off). ROM (Read Only Memory) is non-volatile and stores firmware.
4. Storage Devices
- Hard Disk Drive (HDD): Magnetic storage, large capacity, slower.
- Solid State Drive (SSD): Flash memory, faster, more durable.
- Optical Disc: CD, DVD, Blu-ray — uses laser to read/write.
- Pen Drive: Flash memory, portable.
5. Input/Output Devices
Input Devices: Keyboard, mouse, scanner, microphone, webcam, touchscreen, joystick.
Output Devices: Monitor, printer, speaker, projector, plotter.
6. System Bus
The system bus connects CPU, memory, and I/O devices. It includes:
- Data Bus: Carries data between components.
- Address Bus: Carries memory addresses.
- Control Bus: Carries control signals (read/write).
7. Software Concepts
- System Software: Operating system, device drivers, utility programs.
- Application Software: Word processors, spreadsheets, games.
- Programming Tools: Compiler, interpreter, assembler, debugger.
8. Revision Questions and Answers
Very Short Answer Questions
1. What is the full form of CPU?
Central Processing Unit.
2. Name the two main components of the CPU.
ALU and Control Unit.
3. Is RAM volatile or non-volatile?
Volatile (data lost on power off).
4. Give two examples of input devices.
Keyboard and mouse.
5. What is the function of the system bus?
To transfer data, addresses, and control signals between components.
Short Answer Questions
1. Differentiate between RAM and ROM.
RAM is volatile, read-write, used for temporary data. ROM is non-volatile, read-only, stores firmware.
2. What is cache memory? Why is it used?
Cache is small, fast memory between CPU and RAM. It stores frequently accessed data for faster processing.
Long Answer Questions
1. Explain the block diagram of a computer system and describe each component.
A computer system has: Input Unit (accepts data), CPU (processes data — ALU + CU), Memory Unit (stores data — RAM/ROM), Output Unit (displays results). The system bus connects all components.