D-type, flip-flops,adders and half-adders

Complete the sentence: A ______ can be used to perform the ________

A logic gate circuit can be used to perform the addition of two bits

What is a half adder?

A circuit that performs the addition of two bits

What are the limitations of a half-adder?

The half-adder has only two inputs so it cannot use the carry from the previous addition as a third input to a subsequent addition. it can only add one-bit numbers

What is a full-adder?

A full adder combines two half-adders

Why do we use full adders for generally larger operations?

Full adders allows for addition operations that generates a carry bit to be incorporated into the calculation

What is a concatenated adder?

adds two binary numbers of each of n bits.

n full adders can be connected together to input the carry bit into a subsequent adder along with two new inputs

What is a flip flop

an elemental sequential logic circuit that can store one bit and flip between two states, 0 and 2

What is an edge-triggered D-type flip flop?

Has one input called D and two outputs Q and NOT.

It has a Clock signal input

What is the clock

Another type of sequential circuit that changes state at regular time intervals. A clock is needed to synchronise the change of state of flip flop circuits

What are the uses of D-type flip flops

•D-type flip-flops are used for creating registers and counters

•They are used for the intermediate storage needed during arithmetic operations

•Static RAM is also created using D-type flip-flops

How are D-type flip flops used as a memory unit

•Output Q only takes on a new value if the value
at D has changed at the rising edge of a clock pulse

•This means that the clock pulse will freeze or ‘store’ the input value at D, in Q until the next clock pulse

How does a D-type flip flop work?

The D type flip flop captures the value of the input D on the riding edge of a clock pulse.

The captured value becomes the output