Design of Iterative Systems student version

Design of Iterative Systems student version - EC262 Topic...

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1 EC262 Topic 8: The Design of Iterative Systems Iterative Systems Most of you (I would guess all of you) have computers with microprocessors that support the so-called x86-64 instruction set. This means, among other things, that your computer is able to add together two 64-bit quantities. Let’s consider this problem: You are back in the year 1999, leading the AMD team that is tasked with building a circuit to add two 64-bit binary numbers together. One of your team members vaguely remembers his EC262 class, and announces that such a circuit can be built with a combinational logic circuit. He proposes a system with no modularity—a system that directly inputs the two 64-bit binary numbers to be added (and a carry-in bit) and directly outputs the 64-bit sum (with a possible 65 th carry out bit). He shows you a schematic that looks like a huge vat of spaghetti accidentally spilled on the floor of King Hall (before it is picked up by the cleaning crew and served to hungry midshipmen). You ask your team member: How many lines are in your truth table? What is his reply? The number of lines in a truth table is: If a supercomputer could process 1 billion lines of this truth table every second, how long would it take to examine the truth table? Your team member tells you he tried to implement his circuit on a protoboard, but the sheer number of wires caused flame and smoke. You fire the team member (just as he is offering to show you his 129-variable Karnough map) because you remember from EC262 that there is a better way to do this: Note that this is precisely how you perform addition! You start at the least significant digit, and, digit-by-digit, calculate the sum and carry. Your design can be described by a truth table with ____ lines and with Systems that are built by combining a number of identical blocks are termed The Delay Problem Look at the above picture. Suppose all of the bits in the two numbers to be added—i.e.,
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This note was uploaded on 03/27/2012 for the course ECE 200 taught by Professor Nasis during the Spring '08 term at Drexel.

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Design of Iterative Systems student version - EC262 Topic...

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