1.
Software Developers
View of Hardware
Electronic Circuits
2.
What are circuits?
Computers are electrical devices, so
therefore all functions performed by a
computer need to done via the use of circuits.
Circuits are designed via the use of Logic
Gates which show the path and the way in
which electronic signals are sent and
received.
3.
Logic Gates
Are a hardware circuit that produces a 0 or 1,
which is normally an electronic impulse.
There are THREE basic logic gates and
THREE extended gates that can be used to
build integrated circuits.
4.
BASIC GATES
1. NOT Gate
This is the simplest of all gates, it involves a
single input and a single output.
The purpose of this gate is the flipping of a bit
similar to what is performed in one’s
complement.
24.
EXTENDED GATES
1. NAND Gate
This is involves two inputs to produce one
output.
The output is the opposite of an AND gate.
Is a combination of an AND and NOT gate.
26.
NAND Gate – Truth Table
A B X IF A=1 AND B=1THEN
0 0 1 X=0
0 1 1
ELSE
X=1
1 0 1
ENDIF
1 1 0
27.
EXTENDED GATES
1. NOR Gate
This is involves two inputs to produce one
output.
The output is the opposite of an OR gate.
It is a combination of an OR and NOT.
32.
XOR Gate – Truth Table
A B X
0 0 0
0 1 1
1 0 1
1 1 0
33.
SPECIALITY CIRCUITS
Designed to make use of our binary
knowledge and our circuitry knowledge
Examples include:
Adders
Flip Flops
Shifts
34.
DESIGNING SPECIALITY
CIRCUITS
These circuits are written to provide a specific
function:
Adder (Binary Addition)
Flip Flop (Binary Storage)
35.
DESIGNING SPECIALITY
CIRCUITS
Follow these steps:
Identify inputs and outputs
Identify the components required to produce the
output (AND, OR, NOT, NAND, NOR, XOR)
Construct the solution with logic gates
Check the solution for validity (with a truth table)
Evaluate the circuit design (could you make this
circuit better by chaining different logic gates)
36.
Binary Half Adder
This device is basically a calculator.
Lets look at the half adder truth table first.
37.
Binary Half Adders
INPUT OUTPUT
To create a
Binary Adder, A B Carry Sum
we need to find
a logic gate that
give us the 0 0 0 0
Carry output
and a logic gate
0 1 0 1
the Sum output
1 0 0 1
1 1 1 0
38.
Binary Half Adders
INPUT OUTPUT
Carry output is
created using a A B Carry Sum
AND logic gate
0 0 0 0
A
X
B 0 1 0 1
1 0 0 1
1 1 1 0
39.
Binary Half Adders
INPUT OUTPUT
Sum output is
created using a A B Carry Sum
XOR logic gate
0 0 0 0
A
X
B
0 1 0 1
1 0 0 1
1 1 1 0
40.
Binary Half Adders
The circuit:
A
Carry (C)
B
Sum (S)
41.
Half And Full Adders
Half Adders only work to add two digits
To add more than 2 binary digits we need a full
adder
A full adder allows us to add the “carry” value to
an binary addition
43.
Truth Tables
Construct a truth table for the full adder.
44.
Truth Table
A B CARRY CARRY SUM
IN
0 0 0 0 0
0 0 1 0 1
0 1 0 0 1
0 1 1 1 0
1 0 0 0 1
1 0 1 1 0
1 1 0 1 0
1 1 1 1 1
45.
Circuit Design Steps
Identify inputs and outputs.
A+B+C=X
Identify the components needed to obtain
the desired output.
AND/OR/NOT/XOR/NAND/NOR
Construct a truth table to test.
46.
Activity 2
Construct a truth table for the following
circuit.
A
Y
B X
C
47.
A
B X
C
A B C Y X
0 0 0 1 1
0 0 1 1 0
0 1 0 1 1
0 1 1 1 0
1 0 0 1 1
1 0 1 1 0
1 1 0 0 0
1 1 1 0 1
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