You may see messages appear on your network/internet connection saying there were parity errors and usually you realize your network connection is slower, or that the web pages are not appearing as well.

Parity errors occur when information that is traveling across the network has been damaged in transit.

Usually, it is because you have a bad connection. Disconnecting and reconnecting the network connection will usually solve these. It could be that the connection to your ISP (internet service provider) has hit problems along the way or settings in your PC got confused. Less often, it is an indication that equipment is failing, which could be the network card in your PC, your cable/DSL router or the equipment at your ISP. If it is equipment failing, then resetting the connection will not help.

Parity is how networks determine if information being sent is received intact. When information is sent across the network, it is sent as a bunch of bits, or ones and zeros. These are grouped in bytes, which basically represent one letter or number, as we are used to. Most of the time it takes eight bits to represent one character, though some newer machines are using 16 bits to represent a character.

When the computer sends a byte (eight bits or binary digits), it looks at how many “ones” are in the byte. Then it adds a parity bit to the byte. Assuming we are using even parity, if the number of “ones” in the byte is an odd number, it puts a “one” in the parity bit, or if it’s an even number, it puts a zero. This now means that all the bytes being sent have an even number of “ones” in them.

When the computer receiving the data looks, it first checks if the number of “ones” in the byte is an even number. If it is, then we assume the byte was received as it was sent. If it is an odd number, then we know that the byte was damaged in transit, and that is when you will see messages about parity errors. The receiving computer requests the information be resent, and you will notice a slow-down, as it has to be sent multiple times for one good receiving.

All of this about adding and checking a parity bit occurs behind the scenes inside your computer so you do not know it is happening, except when a large number of parity errors occur, and then you see messages about network problems.

Send your questions to Dwight Watt at dwight@dwightwatt.com. He teaches at a technical college in northwest Georgia and does consulting work for businesses and individuals. His website is dwightwatt.com.