Computer Architecture and Memory Concepts

Module 1

• This module covers computer architecture, programming languages, and structured programming.
• It includes: basics of computer architecture (Von-Neumann), types of programming languages (system and application software, compilers, interpreters, high-level and low-level languages), and introduction to structured programming (algorithm, flowcharts, pseudo-code).

Computer

• A computer is an electronic device that processes data from users, performs calculations and operations, and produces desired output.
• Hardware refers to the physical parts of a computer.
• Software is a set of instructions that guides the computer's operations.
• Data is the input provided to the computer.
• Users are individuals who interact with the computer.

Basics of Computer Architecture (Von-Neumann)

• Proposed in 1945, Von-Neumann architecture is a fundamental computer design.
• It consists of a Control Unit, Arithmetic Logic Unit (ALU), registers, and input/output units.
• This architecture stores instructions, data, and program data in the same memory.
• Data is stored on the computer's hard drive.

Components of Von-Neumann Model

• Central Processing Unit (CPU)
• Memory Unit
• Input Unit
• Output Unit

Central Processing Unit (CPU)

• The CPU performs the majority of data processing operations in a computer.
• Key components include the Arithmetic Logic Unit (ALU), Control Unit (CU), and various registers.
• The ALU handles arithmetic and logical operations.
• The CU manages the execution of computer programs.
• Registers are temporary storage locations within the CPU, holding data and intermediate results.

Arithmetic Logic Unit (ALU)

• The ALU executes arithmetic and logic operations.
• Arithmetic operations include addition, subtraction, multiplication, division, etc.
• Logic operations include AND, OR, NOT, etc.

Control Unit (CU)

• The CU controls the flow of operations within a computer system.
• It manages the data movement and actions of other components.

CPU Registers

• MAR (Memory Address Register): Holds the memory address of data to be accessed.
• MDR (Memory Data Register): Holds data being transferred to or from memory.
• AC (Accumulator): Stores intermediate arithmetic and logic results.
• PC (Program Counter): Contains the address of the next instruction to be executed.
• CIR (Current Instruction Register): Contains the current instruction being processed.

Buses

• Used to share information among CPU registers.
• A bus consists of common lines (one for each bit of a register) enabling data transfer one bit at a time.
• Von-Neumann architecture uses three major bus systems for data transfer (Address, Data, and Control buses).

Types of Buses

• Address Bus: Carries the address of data between the processor and memory.
• Data Bus: Carries data between the processor, memory unit, and input/output devices.
• Control Bus: Carries signals/commands from the CPU.

Memory Unit

• Stores binary data grouped in words.
• The structure of a memory unit is defined by the number of words and bits in each word.
• Classified into: Primary Memory and Secondary Memory

Primary Memory

• Also known as main memory, used to store data and instructions during computer operations.
• Primarily utilizes semiconductor technology and is faster and less costly than secondary memory.
• Types include Read-Only Memory (ROM) and Random Access Memory (RAM).

Random Access Memory (RAM)

• A volatile memory.
• Data is lost when power is turned off.
• It's used for temporarily storing programs or data for processing by the processor.
• Types include Static RAM (SRAM) and Dynamic RAM (DRAM).

Read-Only Memory (ROM)

• Non-volatile memory, meaning data is retained even without power.
• It holds essential instructions for the computer's operation, often containing the initial boot-up instructions.
• Different types include PROM, EPROM, and EEPROM.

Secondary Memory

• Also known as auxiliary memory, it stores a large quantity of data that is permanent.
• It's slower but less expensive than primary memory.
• Data is not accessed directly by the CPU; it must first be transferred to primary memory.
• Examples include magnetic disks (hard drives), magnetic tapes, optical disks (CDs, DVDs), and USB drives.

Memory Hierarchy

• Arranges storage devices based on access speed and cost.
• CPU registers have the highest speed and lowest capacity.
• Secondary memory (hard drives, tapes) has the lowest speed and highest capacity.
• Intermediate levels like cache and primary memory provide a balance between speed and capacity.

Registers

• Smallest memory location in the CPU.
• Typically SRAM (static RAM).
• Holds data words (64 or 128 bits).
• Crucial for processing, including program counters, status word registers, and accumulators.

Cache Memory

• Temporary storage between RAM and the CPU, holding frequently accessed data and instructions.
• Improves processing speed as the CPU accesses data from cache more quickly than from RAM.

Main Memory

• One central storage unit in a computer system.
• Used to store programs and data during computer operations.
• Relatively large and fast compared to secondary memory.

Auxiliary Memory

• Lowest cost and highest capacity storage in a computer system.
• Primarily used for storing large amounts of data for long-term storage or when not immediately needed.
• Includes magnetic disks (hard drives), magnetic tapes, optical disks (CDs, DVDs).

Types of Software

• Software is a set of instructions or commands guiding users on what to do.
  • System Software
    • Interface between application and system, managing system resources & aiding application software operation.
    • Also a general-purpose type of software.
  • Application Software
    • Developed for specific tasks upon user request.
    • Uses high-level languages (C, C++, Java).
    • Examples include MS Office, web browsers, etc.

Programming Languages

• Programs are written in high or low-level languages depending on the task.
  • High-level languages are closer to human language for easier development.
  • Low-level languages (machine language) or assembly language are machine-dependent and difficult to maintain.
  • Machine Language is the only language the CPU directly understands.

System Translators

• Convert programs from one programming language to another.
  • Compiler — converts an entire program into machine code at once.
  • Interpreter — translates and executes one line of code at a time.
  • Assembler — converts assembly language to machine language.

Algorithm and Flowchart

• Algorithm is a step-by-step procedure for solving a problem.
• Algorithm characteristics include:
  • Clear and Unambiguous
  • Well-Defined Input/Output
  • Finite-nes
  • Feasible
  • Language Independent

Flowchart Symbols

• Terminal: Start and Stop
• Input/Output: Data entry/display
• Processing: Calculations or operations
• Decisions: Choices (e.g., if/then statements)
• Flow Lines: Indicate direction of program flow
• Connectors: Linking segments of a flowchart.

Examples of Algorithms (and Flowcharts):

• Reading and displaying two numbers
• Finding the largest of three numbers
• Calculating the sum of n natural numbers.
• Calculating the factorial of a number.
• Creating a Multiplication Table
• Fibonacci Series
• Various other calculations as outlined.

Test your knowledge on computer architecture and memory systems with this quiz. Explore questions related to the functions of the address bus, various types of memory, and key components of Von-Neumann architecture. Ideal for students in computer science and information technology courses.