DE_MF

63



64

Logic diagra

am 65

Odd Parity Gene

erator 66

P=A⊕BE

Ex-NOR C 67

Logic diagr

ram 68

Parity Checke It is a logic circuit that checks for This circuit can be an even pa depending on the type of parity When this circuit is used as even bits must always be even. When a parity error occurs, the ‘sum odd’ output goes high. If t parity checker, the number of inp occurs the ‘sum odd’ output goe high.

err possible errors in the transmission.arity checker or odd parity checker generated at the transmission end.n parity checker, the number of inpute ‘sum even’ output goes low andthis logic circuit is used as an oddput bits should be odd, but if an errores low and ‘sum even’ output goes 69

Even Parity Che• Consider that three input message a at the transmitting end. These 4 bi checker circuit which checks the pos data is transmitted with even parity, an even number of 1s.• If any error occurs, the received me The output of the parity checker is de• The below table shows the truth tabl PEC = 1 if the error occurs, i.e., the f 1s and PEC = 0 if no error occurs number of 1s.

eckeralong with even parity bit is generated its are applied as input to the parityssibility of error on the data. Since the four bits received at circuit must haveessage consists of odd number of 1s.enoted by PEC (parity error check).le for the even parity checker in whichfour bits received have odd number ofs, i.e., if the 4-bit message has even 70



71



72

Logic diagra

am 73

Odd Parity Check Consider that a three bit message a at the transmitting end. Odd parity and checks whether any error are p If the total number of 1s in the da whereas if the total number of 1s is the data is transmitted with odd pari The below figure shows the tru where PEC =1 if the 4-bit message of 1s (hence the error occurre contains odd number of 1s (that m

ker along with odd parity bit is transmitted checker circuit receives these 4 bitspresent in the data.ata is odd, then it indicates no error, even then it indicates the error since ity at transmitting end. uth table for odd parity generator e received consists of even numbered) and PEC= 0 if the messagemeans no error). 74



75

PEC = (A Ex-NOR B) Ex-N

NOR (C Ex-NOR D) 76