STATUS Filter Algorithm
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-27
Using a status filter, to recognize the anomaly of a status byte having valid parity but having an inappropriate combination of status bits for the time of presentation, eliminates certain channel errors which might otherwise hang the channel interface. Channels may hang if presented with inappropriate status. The status filter algorithm detects inappropriate status. If a status byte, received by the channel, has valid parity but is inappropriate, the status filter detects the error to allow for channel recovery. The status filter examines for the following status conditions: Fig. 1 SHORT BUSY SEQUENCE Fig. 2 INITIAL STATUS, NOT COMMAND CHAINING Fig. 3 INITIAL STATUS, COMMAND CHAINING Fig. 4 FIRST STATUS AFTER ZERO INITIAL STATUS Fig.