Monitoring system for a digital data processor

摘要

Internal states of storage devices within a digital data processing system are made accessible using variable mode multi-bit shift register storage devices. The inputs and outputs of these shift register storage devices are interconnected by gating means which may be selectably controlled to form separately selectable serial strings along which the bits of a selected string may be caused to be shifted to a monitoring unit for monitoring, diagnosing and/or correcting purposes and then returned, via the string, to their original locations in the shift register storage devices, after which normal data processing operations can be resumed, or other appropriate action taken.