Tarkistusbytejä

Tarkistusbytejä, known in English as check bytes or parity bits, are a simple form of error detection used in digital data transmission and storage. Their primary purpose is to identify accidental changes to data that might occur during these processes. A tarkistusbyte is an extra bit added to a block of data, such as a byte or a word, in such a way that the total number of '1' bits in the combined data and the tarkistusbyte is either always even (even parity) or always odd (odd parity).

When data is transmitted or stored, the sender or writer calculates the tarkistusbyte based on the parity rule. The receiver or reader then recalculates the tarkistusbyte using the same rule on the received data. If the recalculated tarkistusbyte matches the received tarkistusbyte, it is highly probable that the data has been received correctly. If they do not match, it indicates that an error has occurred somewhere in the transmission or storage.

While effective at detecting single-bit errors, tarkistusbytejä are not capable of correcting errors. They also cannot detect all types of errors, particularly those involving an even number of bit flips. Despite their limitations, tarkistusbytejä are a fundamental and widely used technique due to their simplicity and low computational overhead, often employed in conjunction with more sophisticated error correction codes for critical applications.