Short Notes: Basics of Computer Design | Computer Architecture & Organisation (CAO) - Computer Science Engineering (CSE) PDF Download

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1 Basics of Computer Design in Computer Organization and
Architecture
1.1 Introduction to Computer Organization and Architecture
ComputerOrganizationdealswithhowhardwarecomponentsinteracttoexecuteinstruc-
tions, while Computer Architecture de?nes the structure and behavior of a computer
system. Together, they describe how a computer processes data and executes programs
e?ciently.
1.2 Basic Working Principle of a Computer
• Stored Program Concept: Programs and data are stored in memory, allowing
the computer to fetch, decode, and execute instructions sequentially.
• Von Neumann Architecture: A model with a single memory for both instruc-
tions and data, processed by a CPU with a control unit and ALU.
• Input-Process-Output: Data is input, processed by the CPU, and output as
results.
1.3 Functional Units of a Computer
• Input Unit: Accepts data and instructions (e.g., keyboard, mouse).
• Central Processing Unit (CPU): Includes:
– Arithmetic Logic Unit (ALU): Performs arithmetic and logical operations.
– Control Unit (CU): Directs operations by fetching and decoding instructions.
– Registers: Small, fast storage for temporary data (e.g., PC, IR, ACC).
• Memory Unit: Stores data and instructions (main memory, cache, registers).
• Output Unit: Displays or stores results (e.g., monitor, printer).
1.4 Representation of Basic Information
• Bits and Bytes: Data is represented in binary (0s and 1s); 8 bits = 1 byte.
• Number Systems: Binary, decimal, hexadecimal for representing data.
• Character Encoding: ASCII or Unicode for representing text.
• InstructionFormat: Includesopcode(operation)andoperands(data/addresses).
1.5 Computer Instructions
• Types: Arithmetic(ADD,SUB),logical(AND,OR),datatransfer(MOV,LOAD),
control (JMP, CALL).
• Instruction Cycle: Fetch (retrieve instruction from memory), Decode (interpret
instruction), Execute (perform operation), Store (save results).
• Memory Instructions: Load (fetch data from memory to CPU), Store (write
data from CPU to memory).
1.6 Main Memory Organization
• Main Memory (RAM): Volatile, fast storage for programs and data during ex-
ecution.
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1 Basics of Computer Design in Computer Organization and
Architecture
1.1 Introduction to Computer Organization and Architecture
ComputerOrganizationdealswithhowhardwarecomponentsinteracttoexecuteinstruc-
tions, while Computer Architecture de?nes the structure and behavior of a computer
system. Together, they describe how a computer processes data and executes programs
e?ciently.
1.2 Basic Working Principle of a Computer
• Stored Program Concept: Programs and data are stored in memory, allowing
the computer to fetch, decode, and execute instructions sequentially.
• Von Neumann Architecture: A model with a single memory for both instruc-
tions and data, processed by a CPU with a control unit and ALU.
• Input-Process-Output: Data is input, processed by the CPU, and output as
results.
1.3 Functional Units of a Computer
• Input Unit: Accepts data and instructions (e.g., keyboard, mouse).
• Central Processing Unit (CPU): Includes:
– Arithmetic Logic Unit (ALU): Performs arithmetic and logical operations.
– Control Unit (CU): Directs operations by fetching and decoding instructions.
– Registers: Small, fast storage for temporary data (e.g., PC, IR, ACC).
• Memory Unit: Stores data and instructions (main memory, cache, registers).
• Output Unit: Displays or stores results (e.g., monitor, printer).
1.4 Representation of Basic Information
• Bits and Bytes: Data is represented in binary (0s and 1s); 8 bits = 1 byte.
• Number Systems: Binary, decimal, hexadecimal for representing data.
• Character Encoding: ASCII or Unicode for representing text.
• InstructionFormat: Includesopcode(operation)andoperands(data/addresses).
1.5 Computer Instructions
• Types: Arithmetic(ADD,SUB),logical(AND,OR),datatransfer(MOV,LOAD),
control (JMP, CALL).
• Instruction Cycle: Fetch (retrieve instruction from memory), Decode (interpret
instruction), Execute (perform operation), Store (save results).
• Memory Instructions: Load (fetch data from memory to CPU), Store (write
data from CPU to memory).
1.6 Main Memory Organization
• Main Memory (RAM): Volatile, fast storage for programs and data during ex-
ecution.
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• MemoryHierarchy: Registers,cache,mainmemory,secondarystorage(trade-o?
between speed and cost).
• Addressing: Each memory location has a unique address for data access.
• Stored Program: Instructions and data are stored in memory, accessed via ad-
dresses.
• Memory Types: RAM (Random Access Memory), ROM (Read-Only Memory
for ?rmware).
1.7 BUS Structure
• De?nition: A set of communication pathways connecting computer components.
• Types:
– Data Bus: Transfers data between CPU, memory, and I/O devices.
– Address Bus: Carries memory addresses to specify data location.
– Control Bus: Transmits control signals (e.g., read/write commands).
• Bus Width: Determines the amount of data transferred per cycle (e.g., 32-bit,
64-bit).
1.8 Performance of a System
• Factors: CPU clock speed (MHz/GHz), instruction execution rate (MIPS), mem-
ory access time, bus bandwidth.
• Metrics: Throughput (tasks completed per unit time), latency (time to complete
a task).
• Enhancements: Pipelining,caching,andparallelprocessingimproveperformance.
1.9 Advantages and Disadvantages
• Advantages:
– Modular design allows e?cient hardware interaction.
– Stored program concept enables ?exible program execution.
– Hierarchical memory optimizes speed and cost.
• Disadvantages:
– Complex design increases development cost.
– Bottlenecks in bus or memory access can reduce performance.
– Von Neumann bottleneck: Single memory for data and instructions limits
speed.
1.10 Short Questions and Answers
1. Whatisthedi?erencebetweencomputerorganizationandarchitecture?
Architecture de?nes the systems structure, while organization describes how com-
ponents interact.
2. What is the stored program concept? Storing both instructions and data in
memory for CPU execution.
3. Whatistheroleofthecontrolunit? Itfetches,decodes,anddirectsinstruction
execution.
4. Whatisabusincomputerdesign? Acommunicationpathwayfortransferring
data, addresses, and control signals.
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