combinational logic circuit and sequential logic circuit.

1. Introduction to Logic
Presented to Ehtesham Ul Haq

2. Combinational Logic
Circuit
Combinational digital logic circuits are
basically made up of digital logic gates like
AND gate, OR gate, NOT gate and universal
gates (NAND and NOR gates).All these
gates are combined together to form a
complicated switching circuit.
Examples of combinational circuits
are, Adder, Subtractor, Converter, and
Encoder/Decoder

3. • Characteristics of CLC
• At any instant of time, the
output of combinational logic
circuit depends only on the
present input terminals.
• Memory elements is absent in
combinational circuit. The
combinational logic circuit
doesn’t have any backup or
previous memory.
• No clock signal is required in
combinational logic circuit.
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• The n number of inputs and m
number of outputs are possible in
combinational logic circuits.
• The ‘n’ input variable comes from the
external source while the ‘m’ output
variable goes to the external
destination. In many applications, the
source or destinations are storage
registers.

4. What is display decoder?
A Display Decoder is a combinational circuit which decodes and n-bit input
value into a number of output lines to drive a display.
Time Prayer schedule in mosque. 7 segment Decode.
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5. A B C D E F G
0 1 1 0 0 0 0
0 1 1 0 0 1 1
1 1 1 1 0 0 1

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The seven-segment decoder, which has four input lines and seven output
lines (a, b, c, d, e, f, and g), receives this BCD (A, B, C, and D) input. The
output is provided to a seven-segment LED display that shows the
decimal number depending on the inputs.
The use of packed BCD allows
two BCD digits to be stored
within a single byte (8-bits) of
data, allowing a single data byte
to hold a BCD number in the
range of 00 to 99.

7. A robotic vehicle with the metal detector.
RF-based home automation system.
Automatic health monitoring systems.
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Advantages of CLC:
1) Light emitting diodes (LEDs) are extremely cheap.
2) Seven-segment LED displays are used in a wide range of environments from very hot
to well below freezing.
3) LED displays in general are extremely efficient. Diodes dissipate very little energy.

8. Presentation Title
Sequential Logic Circuit
Sequential logic circuit use flip flop as memory elements and in which
their output is dependent on the input state Sequential logic circuits
have some form of internet “Memory” built in.
This means that sequential logic circuits are able to take
into account their previous input state as well as those actual present.
A sort of “before” and “after” effect is involved with sequential circuits.
Sequential logic circuits are generally termed as two
state or Bisable devices which can have their output or output sets in
one of two basics states.

9. Presentation Title
Characteristics:
1. Output depend on present input and present output
2. Memory element is Present.
3. Clock signal is required.
4. A set/reset flip flop in which activating the “S” Input will switch it to
One stable state and activating the “R” Input will switch it to the other
side.

10. Example:
Sequential logic is used to construct finite-state machines, a basic building
block in all digital circuitry. Virtually all circuits in practical digital devices
are a mixture of combinational and sequential logic.
A familiar example of a device with sequential logic is a television set with
"channel up" and "channel down" buttons.[1] Pressing the "up" button
gives the television an input telling it to switch to the next channel above
the one it is currently receiving. If the television is on channel 5, pressing
"up" switches it to receive channel 6. However, if the television is on
channel 8, pressing "up" switches it to channel "9". In order for the
channel selection to operate correctly, the television must be aware of
which channel it is currently receiving, which was determined by past
channel selections.[1] The television stores the current channel as part of
its state. When a "channel up" or "channel down" input is given to it, the
sequential logic of
the channel selection circuitry calculates the from the input and the
current channel

11. The sequential operation of the JK flip flop is
exactly the same as for the previous SR flip-
flop with the same “Set” and “Reset” inputs.
The difference this time is that the “JK flip
flop” has no invalid or forbidden input states
of the SR Latch

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13. THANK YOU!
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