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Igcse Cs (0478) P1 Notes Chapter 1.3: Hardware and Software 1.3.1 Logic Gates & Circuits

The document discusses hardware and software, specifically logic gates and circuits. It defines logic levels as high or low, true or false, on or off. The basic logic gates (AND, OR, NAND, NOR, XOR) are described and their truth tables shown. The number of combinations in a truth table increases exponentially with the number of inputs - it is 2^n where n is the number of inputs. Logic circuits can have multiple inputs combined using these basic logic gates.

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289 views3 pages

Igcse Cs (0478) P1 Notes Chapter 1.3: Hardware and Software 1.3.1 Logic Gates & Circuits

The document discusses hardware and software, specifically logic gates and circuits. It defines logic levels as high or low, true or false, on or off. The basic logic gates (AND, OR, NAND, NOR, XOR) are described and their truth tables shown. The number of combinations in a truth table increases exponentially with the number of inputs - it is 2^n where n is the number of inputs. Logic circuits can have multiple inputs combined using these basic logic gates.

Uploaded by

collen
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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IGCSE CS (0478) P1 NOTES BY AWAB AQIB

CHAPTER 1.3: HARDWARE AND SOFTWARE


1.3.1 Logic Gates & Circuits

TRUTH TABLES OF LOGIC CIRCUITS

Logic Level Logical Value Binary Value Switch Value


High True 1 On
Low False 0 Off

-Logic gates serve as the building blocks to digital logic circuits using combinational logic
-Many electronic circuits operate using binary logic gates
-Logic gates basically process signals which represent true or false or the equivalent i.e. ON
or OFF, 1 or 0

AND Gate: (A . B) OR Gate: (A + B)


-is only true when both inputs are -is only true when either of the input is
true/1/On/High true/1/On/High

NAND GATE: (A . B) Complement)


NOT GATE: (A Complement) -a NOT AND gate
-inverts the input -whatever the output an AND would give
-is the only single input logic gate to an input, NAND would invert it

1
IGCSE CS (0478) P1 NOTES BY AWAB AQIB
CHAPTER 1.3: HARDWARE AND SOFTWARE
1.3.1 Logic Gates & Circuits

NOR GATE: (A + B) Complement) XOR/EOR GATE: (A ⊕ B)


-a NOT OR gate Complement)
-whatever the output an OR would give to -an Exclusive OR gate
an input, NOR would invert it -is only true when both the inputs are
different

TRUTH TABLES OF INPUTS

-if the logic circuit/network has only 2 inputs then the truth table for them is:
-total combinations are 22=4

A B
0 0
0 1
1 0
1 1

-if the logic circuit/network has only 3 inputs then the truth table for them is:
-total combinations are 23=8
A B C
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1

2
GCSE CS (2210) / IGCSE CS (0478) P1 NOTES BY AWAB AQIB
CHAPTER 1.3: HARDWARE AND SOFTWARE
1.3.1 Logic Gates & Circuits

-if the logic circuit/network has only 4 inputs then the truth table for them is:
-total combinations are 24=16
A B C D
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 0 1
0 1 1 0
0 1 1 1
1 0 0 0
1 0 0 1
1 0 1 0
1 0 1 1
1 1 0 0
1 1 0 1
1 1 1 0
1 1 1 1

Video explanation for combination of Logic Circuits:


https://youtu.be/BnB2m1nXZ84

awabaqibb@gmail.com https://www.youtube.com/c/awabaqib/

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