Data Nibblize and Denibblize Circuitry
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
Disclosed is a circuit that nibblizes and denibblizes binary data in the communication between a host computer and a personal computer through an IBM 3174 or 3274 communication controller. The communication controller is operated by a set of binary commands which are indistinguishable from the actual data that it is supposed to transfer. One way to distinguish commands and the actual data is to transform the data into another format before going into the controller, and retransform the data back after coming out of the controller. The processes of transforming and retransforming are called nibblization and denibblization, respectively. This disclosure uses a 3 to 4 nibblization scheme with a 4 to 3 denibblization scheme.