Computer Architecture | Module 4: Arithmetic Logic Unit (ALU) Design by Prakhar Chauhan | Learn Smarter
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Module 4: Arithmetic Logic Unit (ALU) Design

The chapter provides an in-depth exploration of the design and function of the Arithmetic Logic Unit (ALU), which is crucial for the computations in a CPU. It details key operations of the ALU including basic arithmetic and logical operations, intricacies of integer multiplication and division, and floating-point number representation. Additionally, the chapter analyzes the IEEE 754 standard, emphasizing its impact on numerical accuracy and the design of arithmetic circuits.

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Sections

  • 4

    Arithmetic Logic Unit (Alu) Design

    This section explores the design and functionality of the Arithmetic Logic Unit (ALU), highlighting its operations, structure, and the implementation of arithmetic and logical functions in digital computers.

  • 4.1

    General Alu Design Principles

    This section introduces the fundamental design principles of Arithmetic Logic Units (ALUs), detailing their role in performing arithmetic and logical operations in digital computers.

  • 4.1.1

    Alu Function: Performing Arithmetic And Logical Operations

    This section describes the functions of the ALU in executing arithmetic and logical operations essential for CPU computations.

  • 4.1.1.1

    Arithmetic Operations

    This section discusses basic arithmetic operations performed by the Arithmetic Logic Unit (ALU) of a CPU, such as addition, subtraction, increment, and decrement.

  • 4.1.1.2

    Logical Operations

    This section introduces logical operations in the context of Arithmetic Logic Units (ALUs), essential for digital computing.

  • 4.1.2

    Inputs And Outputs Of An Alu

    This section discusses the essential inputs and outputs of the Arithmetic Logic Unit (ALU), detailing operands, control signals, results, and status flags.

  • 4.1.3

    Basic Logic Gates As Building Blocks: And, Or, Not, Xor

    This section describes the essential logic gates that form the foundation of an Arithmetic Logic Unit (ALU), emphasizing their roles in performing basic digital operations.

  • 4.1.4

    Full Adder And Ripple-Carry Adder: Basic Arithmetic Circuits

    This section covers the fundamental components of binary addition, including the full adder and ripple-carry adder, which serve as essential building blocks in arithmetic circuits within a CPU.

  • 4.1.5

    Look-Ahead Carry Adder: Improving Adder Speed

    The Look-Ahead Carry Adder (LCA) improves the speed of binary addition by parallelizing carry computations, thus overcoming the limitations of the traditional ripple-carry adder (RCA).

  • 4.1.6

    Multi-Bit Alus: Combining Basic Units To Handle Wider Data Paths

    Multi-bit ALUs are constructed by arranging multiple single-bit ALU slices to process wider data paths efficiently.

  • 4.2

    Integer Multiplication Design

    This section covers the hardware implementation and principles of integer multiplication, focusing on both array and sequential multipliers.

  • 4.2.1

    Basic Principles Of Multiplication: Repeated Addition

    This section explains how integer multiplication is fundamentally based on the principle of repeated addition, detailing both the manual technique and its hardware implementation.

  • 4.2.2

    Hardware Implementation Of Unsigned Multiplication

    This section discusses the hardware implementation techniques for unsigned multiplication, focusing on array and sequential multipliers.

  • 4.2.2.1

    Array Multiplier (Combinational/parallel Implementation)

    An array multiplier is a combinational circuit that computes the product of two binary numbers in a single clock cycle, offering high speed through parallel processing.

  • 4.2.2.2

    Sequential Multiplier (Iterative/sequential Implementation)

    The Sequential Multiplier iteratively computes products using registers and an adder, contrasting with faster array multipliers that compute all products simultaneously.

  • 4.2.3

    Booth's Algorithm: Efficient Multiplication For Signed (Two's Complement) Numbers

    Booth's algorithm offers an efficient method for multiplying signed binary numbers in two's complement representation, minimizing the number of required addition and subtraction operations.

  • 4.3

    Integer Division Design

    Integer division is the process of repeatedly subtracting the divisor from the dividend to find the quotient and remainder, with a focus on efficient hardware implementation.

  • 4.3.1

    Basic Principles Of Division: Repeated Subtraction

    This section explains the foundational principle of division in binary, focusing on repeated subtraction and its hardware implementation.

  • 4.3.2

    Hardware Implementation Of Unsigned Division

    This section discusses the hardware implementation of unsigned division in digital computing, covering algorithms like restoring and non-restoring division.

  • 4.3.2.1

    Restoring Division Algorithm

    The Restoring Division Algorithm is a method for executing binary division operations through iterative subtraction, restoring partial remainders as needed.

  • 4.3.2.2

    Non-Restoring Division Algorithm (More Efficient)

    The Non-Restoring Division Algorithm enhances division efficiency by eliminating the restoration step present in traditional division algorithms.

  • 4.3.3

    Signed Division Considerations: Handling Signs Of Dividend, Divisor, Quotient, And Remainder

    This section explains the handling of signs in the division process for signed integers, highlighting the rules for determining the signs of the quotient and remainder.

  • 4.4

    Floating Point Arithmetic

    Floating point arithmetic allows for precise representation of a wide range of numbers, including very large, very small, and fractional values, utilizing a structure reminiscent of scientific notation.

  • 4.4.1

    Motivation For Floating Point Numbers: Representing Very Large, Very Small, And Fractional Numbers

    Floating-point numbers allow for precise representation of very large, very small, and fractional values, overcoming the limitations of integers.

  • 4.4.2

    Structure Of A Floating Point Number: Sign, Exponent, Mantissa (Significand)

    This section discusses the components that make up a binary floating-point number, specifically the sign, exponent, and mantissa, and highlights their roles in representing a wide range of numeric values.

  • 4.4.3

    Normalization: Standardizing The Mantissa

    Normalization in floating-point representation ensures a unique and maximized precision by positioning the binary point right after the first non-zero digit.

  • 4.4.4

    Bias In Exponent: Representing Both Positive And Negative Exponents

    This section explains the concept of bias in the exponent field of floating-point representation, detailing how it facilitates the handling of both positive and negative exponents.

  • 4.5

    Ieee 754 Floating Point Formats

    The IEEE 754 standard defines the representation and arithmetic operations of floating-point numbers, ensuring consistency and reliability across computing systems.

  • 4.5.1

    Single-Precision (32-Bit) Format

    The single-precision format, as defined by the IEEE 754 standard, utilizes 32 bits to represent floating-point numbers, including a sign bit, an exponent, and a mantissa.

  • 4.5.2

    Double-Precision (64-Bit) Format

    This section discusses the IEEE 754 standard for double-precision floating-point format, detailing its structure, bit allocation, and intended use.

  • 4.5.3

    Floating Point Arithmetic Operations

    This section explores floating-point arithmetic operations, highlighting their importance for representing large, small, and fractional numbers.

  • 4.5.4

    Rounding Modes

    Rounding modes in the IEEE 754 standard provide methods to manage precision limitations in floating-point arithmetic.

  • 4.5.5

    Impact Of Floating Point Arithmetic On Numerical Accuracy And Precision

    Floating-point arithmetic is essential for representing a wide array of numbers but introduces limitations, including rounding errors and loss of significance.

Class Notes

Memorization

What we have learnt

  • The ALU is a combinational ...
  • Understanding the hardware ...
  • Floating-point representati...

Final Test

Revision Tests