The document describes the operation of parity checkers and generators, focusing on how binary bits are assessed for odd or even parity using ex-or gates. It details how odd and even parity can be determined through inversion of outputs and provides a practical example of error checking in data transmission. Additionally, it mentions the IC 74180, a TTL parity generator/checker used to detect and generate both even and odd parity.

2. PARITY CHECKER / GENERATOR
Arithmetic Operation – determine the sum of the binary bits in a word is odd or even
Even number of 1’s in n-bit data - Even parity = 1111 0000 1111 0011
 Odd number of 1’s in n-bit data - Odd parity = 1111 0000 1111 0111
PARITY CHECKER
 Ex -OR Gate used to check parity of binary numbers
 Reason – produce high outputs when inputs has odd number of one’s
– produce low outputs when inputs has even number of one’s
 16 - bit EX - OR gate
= Produce high output – number has odd parity
= produce low output – number has even parity

3.  PARITY GENERATION
 Odd parity generator produce odd parity output
 Consider 8 - bit numbers = X7 X6 -------- X0
 Ex : 0100 0001 = even parity
EX – OR Gate = output “0”
Inverter = Output “1”
( Final output = 9 bit = odd parity )
 Ex : 0110 0001 = Odd parity
EX – OR Gate = output “1”
Inverter = Output “0”
( Final output = 9 bit = odd parity )
 This ckt is called odd parity generator
To get even parity = remove inverter

4.  APPLICATION
 Due to transients noise & other disturbances = 1 – bit error occur when binary data
transmitted over telephone lines or other communication paths
 one way to check error = odd parity generator at transmitting end
= odd parity checker at the receiving end
 If no error – receiving data is an odd parity
 If error in the data – receiving data will have even parity
 Ex : 0100 0011 Odd parity generator = output “0 0100 0011”
pass through telephone lines
Odd parity checker at the receiving end
 If no error occur in transmission = odd parity checker produce high output
 If one bit error does creep in the transmitted data = odd parity checker produce low
output indicating the received data is invalid

5.  IC 74180
 14 – pin IC = TTL parity generator – checker
 X7 X6 -------- X0 = input data bits = even or odd parity
 Pin 3 = even input control the operation
 Pin 4 = odd input of the chip
 IC 74180 used to detect even parity or odd parity
 IC 74180 also used to generate even or odd parity