Browse Prior Art Database

Address Data Determination Using Parity Bit

IP.com Disclosure Number: IPCOM000045873D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Jones, RE: AUTHOR

Abstract

Standard commercially available data transmitters use all bit locations but one for data/address information and the one bit location for parity information. Where the attribute of transmitted data as either address or data is to be defined in each transmitted byte, the parity bit is used for this purpose. For any byte containing an address, the parity bit is set to logic 1, and for any byte containing data, the parity bit is set to logic 0. At the receiving station, the actual parity of the received data is examined and compared with the significance of the parity bit to determine whether the parity bit received was a 1 or 0.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Address Data Determination Using Parity Bit

Standard commercially available data transmitters use all bit locations but one for data/address information and the one bit location for parity information. Where the attribute of transmitted data as either address or data is to be defined in each transmitted byte, the parity bit is used for this purpose. For any byte containing an address, the parity bit is set to logic 1, and for any byte containing data, the parity bit is set to logic 0. At the receiving station, the actual parity of the received data is examined and compared with the significance of the parity bit to determine whether the parity bit received was a 1 or 0.

To transmit a byte of information, the parity of the byte is calculated. Then the parity generation of the terminal is set according to whether the byte is an address or data byte, before loading the byte into the transmit buffer. For example, if the byte has even parity and the byte is to be transmitted as an address byte, then the parity of the terminal is set for "odd parity." This causes the parity bit to be transmitted as a "1", indicating an address byte. If the byte is to be transmitted as data, then the terminal is set for even parity.

At the receive terminal, the parity of the received byte is calculated, the parity error flag of the terminal is read, and the expected-parity status of the terminal is checked. Using these three parameters, the state of the parity bit associated with the received...