Fixed Point vs Floating Point - 8.4.1 | 8. Hexadecimal Representation | Computer Organisation and Architecture - Vol 1
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Introduction to Number Representation

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0:00
Teacher
Teacher

Today, we're talking about how numbers are represented in computers. Can anyone tell me what you think 'fixed point' means?

Student 1
Student 1

Is it when the decimal point is always in the same place?

Teacher
Teacher

Exactly right! In fixed point representation, the decimal point stays in one position, which makes calculations straightforward. However, it limits the range of numbers we can represent. What might be an example of a disadvantage?

Student 2
Student 2

You can't represent really big or very small numbers well.

Teacher
Teacher

Correct! Now, does anyone know how floating point representation works?

Student 3
Student 3

Isn't it where the decimal point can move around to allow for larger or smaller numbers?

Teacher
Teacher

Right again! Floating point numbers are flexible and can represent a vast range of values, although they are more complex. Remember the acronym 'SEN': Sign, Exponent, Significand. This will help you recall the key components of floating point representation.

Student 4
Student 4

Can we summarize? Fixed point has a fixed decimal position, limiting range, while floating point can move around to cover more values.

Teacher
Teacher

Excellent summary! Let's move to more details on each.

Managing Positive and Negative Numbers

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Teacher
Teacher

When dealing with integers, how do fixed point and floating point handle negative numbers?

Student 1
Student 1

In fixed point, you might need to use a special bit to represent negative values, like a sign bit.

Teacher
Teacher

Good point! In floating point, we also use a sign bit, but it’s part of a more complex setup with the exponent and significand. What about representing the range of numbers?

Student 2
Student 2

Isn't it true that fixed point has a limited range since it needs to allocate some bits for the integer and some for the fraction?

Teacher
Teacher

Exactly! With 8 bits, if you allocate 4 for the integer and 4 for the fraction, your range is quite limited. On the other hand, how does floating point manage this?

Student 3
Student 3

It can represent a wider variety since the exponent scales the number, right?

Teacher
Teacher

Absolutely! Let's reinforce this with a quick quiz. What is the largest number that can be represented in fixed point with 4 integer bits?

Student 4
Student 4

Hmm, if it’s 4 bits for integer, maximum would be 15 or 1111 in binary?

Teacher
Teacher

Correct! And floating point gives us a different capacity. Great work, everyone!

Applications and Examples

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Teacher
Teacher

Let’s discuss where each of these representations might be used. Can anyone think of applications where fixed point is more beneficial?

Student 1
Student 1

Fixed point would be useful in simpler calculations like financial applications where precision is key.

Teacher
Teacher

Great example! The financial system often uses fixed point to avoid rounding errors. What about floating point?

Student 2
Student 2

Is it used in scientific calculations or anything that requires very large numbers or very small fractions?

Teacher
Teacher

Absolutely right! Floating point is crucial in scientific fields and simulation scenarios. Now, let’s think of a practical representation for the number -9.3. How would we do this in floating point?

Student 3
Student 3

We’d use the sign bit for negative, and the exponent to scale the significand?

Teacher
Teacher

Exactly! Sign bit for negative, and we represent 9.3 in a scale of 2. Fantastic work today, everyone!

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section explores the differences between fixed point and floating point representations of numerical data in computers.

Standard

The section elaborates on fixed point and floating point representations used in computer systems, explaining their structure, benefits, and limitations when dealing with binary and decimal values. Specific mechanisms for representing integers, both positive and negative, are also discussed in the context of various number systems.

Detailed

Detailed Summary

In this section, we delve into two primary types of numerical representation used in computing: Fixed Point and Floating Point. Fixed point representation maintains a steady position for the decimal point, making it straightforward but limiting in the range of values it can represent. Conversely, floating point representation allows the decimal point to move, accommodating a vast range of values but introducing complexity in the encoding structure.

Fixed Point Representation

  • In fixed point representation, the decimal point's position is constant, which restricts the range of values it can express based on the allotted bits for the integer and fractional parts. For example, with 8 bits, one might allocate 4 bits for the integer and 4 bits for the fraction, restricting the representable range to values between -7.5 to +7.5 (for signed representation).

Floating Point Representation

  • The floating point model consists of three parts: the sign bit, the exponent, and the significand (or mantissa). The sign bit indicates whether the number is positive (0) or negative (1). The exponent allows for scaling of the number, while the significand contains the accuracy of the representation. This structure supports a much wider range of values, from very small to very large, which is essential for scientific computations.

Conclusion

Ultimately, the choice between fixed point and floating point representation involves a trade-off between precision, range, and performance.

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Audio Book

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Understanding Binary and Hexadecimal Representation

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So, the similar information I am representing in another number system which is your hexadecimal. Now, you just see what I am saying this is your 8 bit number all 0s to all 1s. So, all 1 in decimal it becomes 255 in hexadecimal it is your FF, FF means 15 F represents 15, 15 × 16^1 + 15 × 16^0. So, in that particular case we will get that this is nothing but 255 in decimal.

Detailed Explanation

In binary, we represent numbers using two digits: 0 and 1. An 8-bit binary number can represent values from 00000000 (0 in decimal) to 11111111 (255 in decimal). In hexadecimal, a base-16 system, we use digits 0-9 and letters A-F to represent values 0-15. The hexadecimal FF represents the value 15 in two 'F' digits, which together form the decimal number 255 by the calculation of (15 * 16^1 + 15 * 16^0). This means there’s a more compact way to write binary values when using hexadecimal, reducing the likelihood of errors.

Examples & Analogies

Think of it like writing a long address. Just as you can write '1234 Elm St.' instead of '1,234,000 Elm Street, New York City, NY', using hexadecimal makes it simpler and less prone to mistakes. Binary is like the long address, while hexadecimal is the abbreviation.

Grouping Bits for Hexadecimal

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So, when we are having a binary representation we simply group them in the 4 bits. So, in that particular case what will happen? We are going to say that this all 1 is going to represent F and all 1 is going to represent F. So, the range is from 00 to FF.

Detailed Explanation

Hexadecimal makes it easier to handle binary by allowing us to group 4 bits together. For example, 0000 in binary equals 0 in hex, while 1111 equals F. By grouping binary digits into sets of four, we can convert long binary strings into short hexadecimal codes. This reduces complexity when working with larger binary numbers.

Examples & Analogies

It’s like organizing your closet: instead of having clothes scattered everywhere, you group them into four sections (shirts, pants, coats, accessories). This makes it much easier to find what you need quickly, similar to how hexadecimal helps us organize and read binary numbers.

Range of Binary Representation

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Now, when we are going to discuss that representation of number in computer or in your binary system or binary digit most of the time we are going to take help of hexadecimal number system because it is having one advantage. Say, when I am going to work with 32 bit number I have to write 32 bits ok all 32 bits 0 or maybe combination of 0s and 1 which is slightly difficult.

Detailed Explanation

In computing, binary numbers can be quite large, which makes them hard to read and write. For instance, a 32-bit binary number consists of 32 individual bits, which can be overwhelming. Hexadecimal simplifies this by allowing us to represent those 32 bits in just 8 characters, as each hex character corresponds to 4 bits.

Examples & Analogies

Imagine trying to fold a large map with hundreds of points; it’s confusing. Now consider having a summarized version with key points highlighted. The summarized version is like hexadecimal representation: it captures the essence of the binary data in a much more digestible format.

Representation of Positive and Negative Numbers

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So, if we are going to represent only positive numbers then what will happen I can use all those 256 character to represent positive numbers from 0 to 255, but if you are going to consider about negative number also this is the number line this is 0 and this is your positive side and this is your negative side.

Detailed Explanation

In an 8-bit system, you can represent 256 distinct values, ranging from 0 to 255 when only positive numbers are used. However, to also include negative numbers, the range would change. For instance, if we include negative numbers, we usually sacrifice some of the positive range resulting in a range typically from -128 to 127 in a system designed to handle both positive and negative numbers.

Examples & Analogies

Think of a thermostat. If it can only display positive temperatures, it shows 0 to 255 degrees. But if it can also show negative temperatures, it needs to adjust its range, bringing the maximum positive temperature down; it might show -128 to +127 to account for freezing conditions.

Sign Magnitude Representation

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For that we are having 2 ways of representing this number one is your sign magnitude in that particular case what will happen? Whatever bit pattern we have it will be divided into two parts one part is known as your sign and other part is your magnitude.

Detailed Explanation

Sign magnitude representation simplifies the way we express numbers by separating the 'sign' (positive or negative) from the 'magnitude' (the actual value). For instance, in an 8-bit number, the first bit might indicate the sign (where 0 is positive and 1 denotes negative), while the remaining bits represent the magnitude of the number.

Examples & Analogies

It’s like labeling a box with ‘Fragile’ (sign) while having the contents as the actual items within the box (magnitude). This way, you can easily tell what kind of contents are inside—whether they are fragile or not—without needing to open the box.

Two's Complement Representation

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For dealing with negative numbers then we use two’s complement. So, in two’s complement just I am giving one example just only getting phone numbers now in that particular case what will happen this is the representation if I am having 0 then these are all 0s, + one is simply that magnitude 1, 10, 11 like that if I go for positive 4 then it will be 100 like that and negative number is coming as - 1 is representing as your all 1s.

Detailed Explanation

Two's complement is widely used for representing negative numbers in binary systems because it simplifies arithmetic operations. In this format, to find a negative number, you invert all bits of its positive counterpart and add one to the result. This allows computers to perform both addition and subtraction using the same hardware.

Examples & Analogies

Imagine flipping a switch; if the switch is on, flipping it off transforms its state, similar to how inverting bits works in two's complement. This method makes it efficient for a computer to switch between positive and negative values using simple binary operations.

Detecting Overflow in Calculations

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Now, what will happen we are working with 8 bit numbers; that means, we are having provision to store this particular 8 bits only and this is a carry out which is not a part of my number because I can represent the number with the help of 8 bits only.

Detailed Explanation

When performing addition or subtraction in binary, if the result exceeds the maximum number that can be stored within the fixed number of bits (in this case, 8), it causes an overflow. Since the extra carry cannot be stored, it can lead to erroneous results, making it crucial to detect and manage overflow conditions.

Examples & Analogies

Think about trying to fit too many items in a suitcase: if you exceed the suitcase's capacity, things will spill out, similar to how a computer losing data can lead to incorrect results. This is why monitoring the limits is essential in both packing and computing.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Fixed Point: A representation method where the decimal point does not move.

  • Floating Point: A flexible representation for wide-ranging numerical values.

  • Sign Bit: The bit that designates the sign of a number.

  • Exponent: A component that scales the value in floating point.

  • Significand: Represents the precision of a floating point number.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • In a fixed point representation using 8 bits, we could represent the integer 3.75 as 0011.1100.

  • In floating point, the number -23 would be represented with a sign bit of 1, followed by the exponent and significand determining its scale.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎵 Rhymes Time

  • If the point is fixed and numbers are small, in finance it helps to stress precision for all.

📖 Fascinating Stories

  • Imagine a farmer weighing her crops in fixed baskets, always knowing the exact weight but limited to how many she can carry. Meanwhile, a bird flying high can see far and wide, representing the floating point—able to take in vast numbers but sometimes not so precise.

🧠 Other Memory Gems

  • Remember 'SEN' for floating point: Sign, Exponent, Notation (Significand) to recall its structure.

🎯 Super Acronyms

FPTS - Floating Point

  • Two parts + Sign
  • represents big numbers with grace.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Fixed Point

    Definition:

    A numerical representation where the position of the decimal point is fixed, limiting the range of representable values.

  • Term: Floating Point

    Definition:

    A numerical representation that allows the decimal point to move, providing a wider range of values at the cost of increased complexity.

  • Term: Sign Bit

    Definition:

    The bit in a number representation that indicates whether the value is positive or negative.

  • Term: Exponent

    Definition:

    The part of a floating-point number that indicates the scale or magnitude of the number.

  • Term: Significand

    Definition:

    The part of a floating-point number that contains its significant digits.

  • Term: Binary Representation

    Definition:

    The representation of data using two symbols: 0 and 1.