Control device for directing execution of forced operations in a data processing system

US4398247A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Dieter Bazlen · Stuttgart, DE
• Dietrich W. Bock · Schenefeld, DE
• Klaus J. Getzlaff · Schenefeld, DE
• Johann Hajdu
• Helmut Painke · Eppelheim, DE

Key dates

• Filing date: Sep 12, 1980
• Grant date: Aug 9, 1983
• Expiry date: Sep 12, 2000

Classification

• Technology area (CPC G): Physics
• CPC primary: G06F9/3836
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

In executing and controlling internal data flow for a particular program, it is often necessary to delay execution of an instruction by the insertion of an appropriate number of wait cycles. Thus, it may be necessary to interrupt instruction execution, for example, to insert a given number of wait cycles for channel access to common storage of the data processing system, for reloading a data or instruction buffer, or for a like situation. In such cases, the control unit has to ignore the particular instruction awaiting execution and execute another forced operation instead. An appropriate code is provided for a NO OPERATION instruction, say all bits zero. When a forced operation is to be executed, this code can be generated with fewer logic means at the output of the instruction register. As a result, there are no control signals active at the output of the decoder. The signals indicating forced operations have to be considered by the decoder only if a control signal is to be generated. If the control signals need be grouped for physical reasons, it is possible to determine which of these signals are a function of forced operations. This will negate the need to otherwise distribute…