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COMPUTER ARCHICTURE AND ORGINATION Basic Structure of Computer H/W & S/W: Functional Units, Basic Operational Concepts, Bus structures, Addressing Methods and Machine Program Sequencing: Memory Locations, Addresses, Instruction and instruction sequencing, Addressing Modes. Basic I/O Operations

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COMPUTER ARCHICTURE AND ORGINATION 

UNIT 1 BASIC STRUCTURE OF COMPUTER  

SHORT NOTES



COVERED TOPICES:- Basic Structure of Computer H/W & S/W: Functional Units, Basic Operational Concepts, Bus structures, Addressing Methods and Machine Program Sequencing: Memory Locations, Addresses, Instruction and instruction sequencing, Addressing Modes. Basic I/O Operations.

CAO UNIT NO.1
Topics and Questions Asked In Previous Exam

1) Basic Structure of Computer H/W and S/W:

1.1 Functional Units of Computer:

Q.1 Explain Functional Units of Computer?

1.2 Basic Operational Concepts:

Q.2 Explain Connections between the Processor and Memory?

1.3 Bus Structures:

Q.3 Explain Single Bus Structure?
Q.4 Draw the diagram & Explain single bus structure :-( Asked in Exam)

1.4 Addressing Methods and Machine program Sequencing:

1.4.1 Memory Locations and Addresses:

1.4.1.1 Byte Addressability

1.4.1.2 Big Endian and Little Endian

1.4.1.3 Word Alignment

1.4.1.4 Accessing Numbers, Characters and character Strings

Q.4 Explain Memory Locations and Addresses?
Q.5 Explain following terms with neat sketch :-( Asked in Exam)

(a) ByteAddresssbility

(b) Big Endian and Little Endian.

Q.6 Explain Big Endian and Little Endian assignment in brief :-( Asked in Exam)

1.5 Instruction and Instruction Sequencing:

1.5.1 Register Transfer Notation

1.5.2 Assembly Language Notation

1.5.3 Basic Instruction Types

1.5.4 Instruction Execution and Straight line Sequencing

1.5.5 Branching

1.5.6 Condition Codes

Q.6 Explain Instruction and Instruction Sequencing?
Q.7 Explain Instruction Execution and Straight line Sequencing?

1.6 Addressing Modes: (Asked in Exam)

Q.8 What is addressing modes? Explain following addressing modes with
Example and illustrations mentioning advantages and disadvantages.

(i) Direct (ii) Register Indirect (iii) Stack. (Asked in Exam)

Q.9 What are addressing Modes? Explain with suitable example
(Asked in Exam)

1.7 Basic Input/Output Operations:

Q.8 Explain Bus Connection For processor, keyboard and display?
Q.9Explain basic I/O operation with Suitable diagram. (Asked in Exam)
1. Functional Units:


Functional units are the building blocks of a computer system, each performing specific tasks essential for processing data:

  • Arithmetic Logic Unit (ALU): This unit carries out arithmetic and logical operations, such as addition, subtraction, AND, OR, etc. It performs computations based on instructions provided by the CPU.
  • Control Unit (CU): The control unit manages the execution of instructions. It fetches instructions from memory, decodes them into signals that control other parts of the CPU, and coordinates the flow of data between the CPU and other hardware components.
  • Memory Unit: This unit stores data and instructions temporarily or permanently. It includes various types of memory, such as RAM (Random Access Memory) and ROM (Read-Only Memory).
  • Input/Output (I/O) Unit: The I/O unit facilitates communication between the computer and external devices, such as keyboards, mice, printers, etc. It manages data transfer between the CPU and peripherals.
  • Registers: Registers are small, high-speed memory locations located within the CPU. They store data temporarily during processing, holding operands, addresses, and intermediate results.

2. Basic Operational Concepts:

Several fundamental concepts govern the operation of computer systems:

  • Instruction Cycle: The instruction cycle is the process through which the CPU retrieves, decodes, executes, and stores instructions. It includes fetching the instruction from memory, decoding it to determine the operation to be performed, executing the operation, and storing the result.
  • Machine Cycle: The machine cycle comprises the series of operations performed by the CPU to execute a single instruction. It typically includes four stages: fetch, decode, execute, and store.
  • Clock Cycle: The clock cycle is the basic unit of time used to synchronize operations within the CPU. It is determined by the system's clock frequency and is measured in nanoseconds or picoseconds.

3. Bus Structures:



Buses are communication pathways that allow data to be transferred between various components of the computer system:

  • Address Bus: The address bus carries memory addresses from the CPU to memory modules. It specifies the location in memory to read from or write to.
  • Data Bus: The data bus transfers data between the CPU, memory, and other peripherals. It carries the actual data being processed or transferred.
  • Control Bus: The control bus manages the control signals used to coordinate activities between different parts of the computer. It includes signals for operations such as read, write, interrupt, etc.

4. Addressing Methods:

Addressing methods determine how the CPU identifies and accesses data and instructions in memory:

  • Direct Addressing: In direct addressing, the instruction specifies the exact memory address of the data or instruction to be accessed.
  • Indirect Addressing: Indirect addressing involves using a memory location to store the address of the data or instruction to be accessed.
  • Indexed Addressing: Indexed addressing adds an offset value to a base address to calculate the memory location of the data or instruction. It allows for more flexible addressing of data structures.

5. Machine Program Sequencing:

Machine program sequencing involves organizing and executing instructions in a specific order:

  • Memory Locations: Each instruction and data item in the computer's memory is assigned a unique address. Memory locations are referenced by these addresses.
  • Addresses: Addresses are numeric identifiers used to locate specific memory locations. They are used by the CPU to fetch instructions and data during program execution.
  • Instruction Sequencing: Instruction sequencing refers to the order in which instructions are executed by the CPU. It follows a sequential or branching logic based on program flow.
  • Addressing Modes: Addressing modes are techniques used to specify the operands or data involved in an instruction. Common addressing modes include immediate, direct, indirect, etc.

6. Basic I/O Operations:

Input/output operations involve transferring data between the computer system and external devices:

  • Polling: In polling, the CPU repeatedly checks the status of the I/O device until it is ready to send or receive data. It is a simple but inefficient method of I/O operation.
  • Interrupts: Interrupts are external signals generated by I/O devices to request the attention of the CPU. They allow for asynchronous communication and enable the CPU to handle multiple tasks simultaneously.
  • Direct Memory Access (DMA): DMA is a method where the I/O device communicates directly with the memory, bypassing the CPU for data transfer. It improves efficiency by offloading data transfer tasks from the CPU.