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What is a combinational circuit? And why should we learn how to design those circuits? In this lecture, 
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answering these questions, I will introduce you to these types of circuits. 
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A combination circuit is a logical circuit whose outputs depend only on the state of its inputs. 
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Therefore, it doesn't have any memories or circuits (such as feedbacks) that use some data from the 
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past.
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Any changes on the input states may have an impact on the output after a delay.
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These are examples of combinational circuits.
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Simple arithmetic and logical expressions are examples of combinational circuits as their outputs only
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depend on the value of their inputs.
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Some of the software programming structures such as if-else, loops, and switch-case also can be synthesised 
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into combinational circuits.
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Combinational circuits can be used to implement a wide range of applications, some of them are shown 
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in this slide.
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These applications can be categorised into five groups: controllers,  arithmetic and logical 
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expressions, data transmission circuits, code conversions, and as a basic block in sequential 
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circuits.
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Combinational controllers can directly drive simple matrix keyboards, LEDs, and displays such
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as a 7-segment. Arithmetic and logical expressions can include additions, multiplications, divisions,
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and comparators.
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Examples for data transmission circuits are multiplexers and demultiplexers.
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BCD encoders and decoders are examples of code conversions.
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Also, sequential circuits are built on top of the combinational circuits.
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In other words, combinational 
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circuits are the basic blocks in designing different types of sequential circuits.
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Timing is one of the main factors in designing a high-performance digital circuit. 
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So the question is What is the delay in a computational circuit, and how can we measure that?
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These are the questions that will be answered in the next lecture. 
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These are our takeaway messages.
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•A combinational circuit can have m binary inputs and n binary outputs. •The outputs of a combinational 
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logic circuit only depend on the state of its inputs.
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Now the quiz question. Which circuit can be combinational?
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Traffic light controller,  4-bit integer multiplier, Binary counter, 	A three-layer perceptron neural
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network,  A recurrent neural network