Looking for comprehensive PGDCA (Post Graduate Diploma in Computer Applications) notes on the Central Processing Unit (CPU) for the 2026–27 academic session? Access complete theory explanations, block diagrams, short notes, long analytical answers, objective MCQs, and exam-oriented solutions covering CPU architecture, Arithmetic Logic Unit (ALU), Control Unit (CU), CPU Registers (PC, MAR, MDR, IR, Accumulator), Machine/Instruction Cycle (Fetch-Decode-Execute), clock speed, and system bus organization tailored for university diploma exams.
Central Processing Unit (CPU)
Definition for Exam:
The Central Processing Unit (CPU), often termed the brain of the computer, is the primary electronic circuit that fetches, decodes, executes, and controls all instructions within a computer system.
Functional Sub-Units of the CPU:
- Control Unit (CU): Directs traffic across hardware components by issuing timing and control signals; acts as the manager of the CPU.
- Arithmetic Logic Unit (ALU): Performs all mathematical calculations (addition, subtraction, multiplication) and logical comparisons (<, >, =, neq).
- Registers: High-speed internal storage locations inside the CPU that temporarily hold data, memory addresses, and execution state (e.g., Accumulator, Program Counter).
PGDCA Central Processing Unit CPU Notes
Q1. What are the two primary components of the CPU? [2 Marks]
Answer:
- Control Unit (CU): Manages instruction execution and hardware signaling.
- Arithmetic Logic Unit (ALU): Performs mathematical calculations and logical evaluation.
PGDCA ALU Control Unit Registers Important Questions 2026-27
Q2. What is the main function of the Control Unit (CU)? [2 Marks]
Answer: The Control Unit acts as the manager of the computer. It fetches instructions from memory, decodes them, and sends control signals to the ALU, registers, and I/O devices to execute the instruction in proper sequence.
Q3. Describe the functions of CPU Registers with two examples. [3 Marks]
Answer: Registers are high-speed, temporary storage locations integrated directly inside the CPU chip to hold immediate data, addresses, and instructions.
- Program Counter (PC): Holds the memory address of the next instruction to be fetched.
- Accumulator (AC): Holds the intermediate result generated by the ALU.
PGDCA Instruction Cycle and CPU Architecture Solutions
Q4. What operations are performed by the Arithmetic Logic Unit (ALU)? [2 Marks]
Answer:
- Arithmetic Operations: Basic math calculations like Addition, Subtraction, Multiplication, and Division.
- Logical Operations: Comparisons such as AND, OR, NOT, and relational checks (<, >, =, neq).
Q5. Explain the Instruction Cycle (Fetch-Decode-Execute). [3 Marks]
Answer: The CPU executes every instruction through a continuous cycle:
- Fetch: The Control Unit retrieves the instruction from primary RAM using the memory address in the Program Counter.
- Decode: The Control Unit interprets the instruction binary code to determine required actions and operands.
- Execute: The ALU or Control Unit performs the specified operation and saves the output to a register or RAM.
Central Processing Unit CPU PGDCA Syllabus Question Answer
⚡ PGDCA Exam Preparation Notice: This page provides curated PGDCA (Post Graduate Diploma in Computer Applications) Central Processing Unit (CPU) Study Material & Solutions updated for the 2026–27 academic session. This complete guide features functional block diagrams of the CPU, step-by-step Fetch-Decode-Execute instruction cycle breakdowns, register organization tables, Control Unit operations (Hardwired vs. Microprogrammed), and high-yield exam questions designed to help you secure top marks in your semester examinations.
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