Abstract: A method and apparatus are provided for observing the progress in time of an object program executed by a computer system. Information items relating to the flow of the object program are detected by an observation tool at an interface of the computer system being evaluated. Unambiguously identifiable observation points in the form of output commands are inserted at specifically selected points in a source program allocated to the object program. The observation points are stored in a table in a database in the observation tool. When the source program is executed, identification signals associated with the observation points are sent to the observation tool by the computer system. The observation tool calculates object program events which specify object program execution times for each object computer of the computer system. The calculated events are evaluated in the observation tool in the program language of the source program with reference to the observation points stored in table form.

Abstract: When a fault is detected in a processor, program execution in this processor is interrupted and taken up again by a standby processor from an earlier uncorrupted state, a recovery point. Such recovery points are specially provided in the program. A save copy of the state at the recovery points is created in each case in a state save unit by recording changes compared with the respective previous state. The data memory existing in the state save unit has pairs of memory words, in which arrangement the state at the recovery point last reached is in each case saved in one of the memory words and the current changes are in each case recorded in the respective other memory word. The memory words are accessed via pointers which are formed by a control logic from two check bits allocated to each memory word pair. Processing of the check bits and of the pointers is very fast. It is not necessary to copy data within the state save unit. The standby processor has direct access to the saved data.