What is BODMAS Rule?
Everyone has studied this rule in their childhood. It stands for "bracket, "off", "division", multiplication", addition",subtraction". A mathematical operation involve a number of operators but they must carry out in a particular order. The circuit described here will help you to practically implement the BODMAS rule which we have studied.
Fig. 1: Prototype of BODMAS rule using IC's on Bread board
The circuit is made with the help of three IC’s namely and few more components they are as follows-
1.7404– 7404 is a hex inverter or NOT gate IC. It is a 14 pin IC and contain 6 individual NOT gate on a single IC. To understand the working of IC we must know about its truth table. 7404 IC gives output as one when the input is zero and output as zero when input is one. That’s why it is called as an inverter. In this first pin is for input and second is for output. Similarly 3 is for input 4 is for output and so on.
2. 7408– 7408 is a quad 2 input AND gate IC. It contains 4 individual AND gate on a single IC. Before understanding its working we should know about its truth table. It will give you output as one when both the input signals applied should be one. If any one of the input is zero we will receive output as zero. In this pin1 and 2 is for input and 3 is for output. Similarly pin 4 and 5 is for input and 6 is for output and so on.
3. 4073– 4073 is a triple 3 input AND gate. It contains 3 individual AND gate on a single IC. Before understanding its working we should know about its truth table. It will give you output as one when all the input signals applied should be one. If any one of the input is zero we will receive output as zero. In this pin1, 2 and 8 is for input and 9 is for output. Similarly pin3, 4 and 5 is input and 6 is for output and so on.
4. LED– LED stands for light emitting diode. It is made up of semiconductor device which emit different light source as its output. LED is a semiconductor diode that emits narrow-spectrum light when electrically biased in the forward direction of the p-n junction. When LED is switched on , the electrons combine with the hole and the device releases energy in the form of light. LED are Available in Red , Orange, Amber, Yellow, Green, Blue and White. Now a day’s LED’s are available in visible, ultraviolet and infrared wavelengths and have high brightness.
5. Switch– Switches MAKES OR BREAKS electrical path. Switches passes or interrupts the electrical current, depending on its position. It can be directly manipulated by human as a control and provide control signal to on or off a device. Switches are electromechanical devices having one or more sets of electrical contacts when they are connected to some external circuit. An ideal switch does not have voltage drop when closed and also have zero rise and fall time when the position of the switch is change form on to off or vice versa.
6. Resistor– A
Working of the circuit
In this circuit we have used –
Switch S1 and LED1 for “bracket” (B).
Switch S2 and LED2 for “of” (O).
Switch S3 and LED3 for “division” (D).
Switch S4 and LED4 for “multiplication” (M).
Switch S5 and LED5 for “addition” (A).
Switch S6 and LED6 for “subtraction” (S).
Initially when no switch is pressed then all the inputs of IC2 and IC3 are high and all the inputs of IC1 is low.
Suppose you have pressed Switch S1, S2, S3 respectively for Bracket (B), of (O) & division (D). Then LED1 will glow this happens because input pin 1 of IC1 receives high signals from S1 therefore its output pin 2 becomes low. This low output will make the pin 1 of IC2 to low hence output pin 3 of IC2 also become ( according to truth table) and LED2 will not glow. Similarly this pin 2 is connected to pin 5 of IC2 whose output pin 6 also becomes low, this in turn make the pin 9 of IC2 also low and LED3 will also not glow. Therefore we can say that B has higher priority than all.
Now suppose we have pressed Switch S3, S4 & S5 respectively for Division (D), Multiplication (M) and Addition (A). Then pin 10 of IC2 become high and pin 9 of IC2 has been already high, according to truth table we will receive high at pin 8 of IC2 and LED3 glows to indicate this. Because of S3 pin 5 of IC1 become high and pin 6 becomes low. This low is given to pin 2 of IC3 because of that output pin 9 of IC3 become low and LED4 will not lit. This pin 2 of IC3 is also connected to pin 4 which will make output pin 6 of IC3 also low because of that pin 12 and 13 of IC2 also become low and LED 5 will not glow. Therefore it is verified that D has highest priority in comparison to D and M.
Now when you press S2, S4, S6 respectively. Then pin 3 of IC1 become high and output of pin 4 of IC1 become low and this low output will make pin 4 of IC2 also low, because of that pin 6 of IC2 also become low and we will receive low at output pin 8 (refer to truth table) therefore LED 3 will not glow. Similarly S4 is pressed which will make pin 8 of IC1 also low and pin 5 of IC3 also becomes low and this one low will make output pin 6 of IC3 also low and we will get low output on pin 11 of IC2 and LED 5 will also not glow. Like S6 is pressed pin 11 of IC3 is already low that’s why LED6 will also not glow. But pin 1 of IC2 is high when switch S2 is pressed and this will make output pin 3 of IC2 high and LED2 will glow. Therefore we can see that in all O has highest priority in all switch which we have pressed.
Similarly you can verify all.