Computer Architecture

Introduction to Computer Systems Architecture

ICT121 Lecture 1

ICT121-Number Systems, Computer Arithmetic and Computer Logic

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Introduction

In this you will learn:

Seminar1: Number Systems, Computer Arithmetic and Computer Logic Seminar2: Overview of a Computer System Seminar3: Computer Function and System Buses Seminar4: Central Processing Unit and Instruction Code Programming Seminar5: Computer Internal Memory Seminar6: Computer Input/Output

ICT121-Number Systems, Computer Arithmetic and Computer Logic

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Number Systems, Computer Arithmetic and Computer Logic

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You will Learn to:

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Convert a number from one number system to another Represent integer in binary using sign-magnitude and two’s complement Represent real numbers in binary Perform simple arithmetic operations using various binary representations Perform logic operation using binary numbers

ICT121-Number Systems, Computer Arithmetic and Computer Logic

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Computer Data

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Data in a computer is represented using binary codes called Binary Digits (bits)

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0 and 1 Integer Real Number Character

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basic data types are:

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ICT121-Number Systems, Computer Arithmetic and Computer Logic

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Integer Representation

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Only have 0 & 1 to represent everything Positive numbers stored in binary

e.g. 41=0010 1001

No minus sign No period Use Sign-Magnitude & Two’s complement

ICT121-Number Systems, Computer Arithmetic and Computer Logic

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Sign-Magnitude

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Left most bit is sign bit 0 means positive 1 means negative +18 = 0001 00102 -18 = 1001 00102 Problems

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E.g. +5 = 0000 0101 -3 = 1000 0011

Need to consider both sign and magnitude in arithmetic Two representations of zero (+0 and -0) (Hence it is NOT done this way in computers)

ICT121-Number Systems, Computer Arithmetic and Computer Logic

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Two’s Complement Numbers

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Examples:

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+3 = 0000 00112 +2 = 0000...