Design and Floating Point Unit 3 – Adder Subtractor

Design and Floating Point Unit 3 – Adder Subtractor. Computer Architecture and Design (FPU).

What you’ll learn

  • Full Adder Subtractor Design in Logisim
  • Normal and Subnormal Numbers
  • Special Values (NaN , Infinity, Zero)
  • Following IEEE754
  • Intuition from Excel (VBA) Simulations
  • Overflow, Underflow
  • Nearest Even Rounding


  • Basic Addition and Subtraction

Adder Subtractor Course Description

Welcome to the course.

This is the third course in a series on designing a floating point unit. The first course dealt with the theory of floating point numbers and the second course covered the design of a multiplier. In this third course we will continue with the design of an adder and subtractor. You do not need to have completed the previous two courses to continue with this one, but if you are new to floating point numbers I would suggest covering the first course before attempting this one.

We start off with the mathematical modelling of the addition and subtraction of 32 bit binary floating point numbers. We then take that mathematical model and implement it in Excel VBA. This allows us to follow the 1’s and 0’s so as to give us a really good understanding of what is happening. After this we then look at the dual path architecture that we are going to use to build the adder subtractor in Logisim.

This design follows the IEEE754 standard and covers both normal and subnormal numbers, special values, edge conditions and rounding.

This is the third course in a suite of 6 courses covering everything you need to know in order to design a floating point unit.

If this sounds like the course you have been looking for then sign up and let’s get started.

Who this course is for:

  • Computer scientists and everyone interested in how computers work

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