CPU (Central Processing Unit) – Notes for Exams
🔹 Definition
CPU stands for Central Processing Unit. It is the "brain" of the computer responsible for carrying out all processing tasks — arithmetic, logic, control, and input/output operations.
🧠 Main Components of CPU
| Component | Function |
|---|---|
| ALU (Arithmetic Logic Unit) | Performs arithmetic and logic operations |
| CU (Control Unit) | Directs operations of the processor and controls flow of data |
| Registers | Small, fast storage locations for temporary data |
| Cache Memory | High-speed memory close to CPU for quick data access |
🖥️ CPU Working Steps
-
Fetch – Retrieves instruction from memory.
-
Decode – Decodes the instruction.
-
Execute – Executes the instruction.
-
Store – Stores the result (if needed).
⚙️ CPU Types
-
Single-core CPU – Can execute one instruction at a time.
-
Multi-core CPU – Can execute multiple instructions simultaneously.
-
RISC – Reduced Instruction Set Computer
-
CISC – Complex Instruction Set Computer
⚡ Important Points for Exams
-
CPU is also called Processor or Microprocessor.
-
The first microprocessor: Intel 4004, introduced in 1971.
-
CPU speed is measured in GHz (Gigahertz).
-
Common CPU manufacturers: Intel, AMD, Qualcomm (for mobiles).
-
Modern CPUs are multi-core (dual-core, quad-core, octa-core).
📌 Frequently Asked MCQs & PYQs (Bank, SSC, JKSSB)
✅ PYQ 1 (SSC CHSL 2021):
Q: What is the main function of the ALU in the CPU?
A: Performs arithmetic and logic operations. ✅
✅ PYQ 2 (JKSSB 2020):
Q: The CPU is also known as:
A. Memory
B. Software
C. Brain of the computer
D. Output device
A: ✅ C. Brain of the computer
✅ PYQ 3 (IBPS Clerk 2019):
Q: What part of the CPU controls the flow of data and instructions?
A: Control Unit (CU) ✅
✅ PYQ 4 (SSC CGL 2018):
Q: Which component holds data temporarily and is part of the CPU?
A. RAM
B. Register
C. ROM
D. Hard Drive
A: ✅ B. Register
✅ PYQ 5 (JKSSB Finance Assistant 2021):
Q: Which of the following is not a part of the CPU?
A. ALU
B. Control Unit
C. RAM
D. Registers
A: ✅ C. RAM
✅ PYQ 6 (SBI PO 2020):
Q: Which memory is fastest and located near or inside the CPU?
A. RAM
B. ROM
C. Cache
D. Hard Disk
A: ✅ C. Cache
📝 One-Liner Quick Facts for Last-Minute Revision
-
CPU = Central Processing Unit
-
ALU = Performs calculations
-
CU = Controls everything inside CPU
-
Registers = Temporary fast memory inside CPU
-
Cache memory is faster than RAM
-
CPU speed measured in GHz
-
CPU handles both data processing and control flow