Flipflops

FLIP FLOPS

·         A flip flop is a sequential loic device used to store one bit information. It is also called as bi-stable device since it has two possible states: 1 (high) and 0 (low).

Types of flip flops:

1.       RS flip flop.

2.       Clocked RS flip flop.

3.       D flip flop

4.       J-K flip flop.

5.       T flip flop.

RS flip flop:

·         RS flip flop has two inputs labelled S and R. The two outputs are labelled Q and Q. In flip flops the outputs are always complementary. In other words, if output Q =1, then output Q=0, and so on. The letters R and S are often referred as set and reset inputs.

                                                

  Truth table

S	R	Q(n+1)	Comments
0	0	Qn	No change
0	1	0	Reset
1	0	1	Set
1	1	x	Not allowed

·        

A  high S (S=1) and low R (R=0) results in the set state (Q=1).

·         A low S (S=0) and high R (R=1) results in the reset state (Q=0).

·         When both inputs are low (S=0, R=0), results in no change in output(Q= lastvalue).

·         When both inputs are high (S=1, R=1), results in indeterminate state and this is known as race condition.

Read More

Number systems

Number systems

1.       Decimal number system

2.       Binary number system

3.       Octal number system

4.       Hexa decimal number system

Decimal number system:

·         There are 10 characters namely 0,1,2,3,4,5,6,7,8,9 and the base is 10.

·         Example:  (i)(0.7)₁₀    (ii) (24)₁₀

Binary number system:

·         There are 2 characters namely 0 and 1, and the base is 2.

·         Example:  (i) 1100₂  (ii) 110.11₂

Octal number system:

·         There are 8 characters namely 0,1,2,3,4,5,6,7 and the base is 8.

·         Example: (i) 236₈  (ii) 566₈

Hexadecimal number system:

·         There are16 characters, namely 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F and the base is 16.

·         Example: B86₁₆  (ii) 1A2.8₁₆

Relation among different number systems

Decimal	Binary	Octal	Hexadecimal
0	0000	00	0
1	0001	01	1
2	0010	02	2
3	0011	03	3
4	0100	04	4
5	0101	05	5
6	0110	06	6
7	0111	07	7
8	1000	10	8
9	1001	11	9
10	1010	12	A
11	1011	13	B
12	1100	14	C
13	1101	15	D
14	1110	16	E
15	1111	17	F

Read More

Full adder

Full adder:

·         A full adder has three inputs and two outputs. It can add 3digits at a time. The two inputs are A and B and third input is C_in from the carry generated by the previous addition. It produces two outputs, SUM and CARRY.

Read More

Half adder

Half adder 

Half adder:

·         Half adder has two inputs and two outputs. It can add 2 bits at a time and produce 2-bit data(SUM and CARRY). It circuit consists of an EX-OR gate and AND gate.

·         The outputs of EX-OR gate is called the SUM(S), while the output of AND gate is known as CARRY(C).

·         This circuit is called half adder because it cannot accept a CARRY from the previous additions. Hence half adder circuit can be used for binary addition of lower most bit only.

Read More