Browse Prior Art Database

Program Loop Detector

IP.com Disclosure Number: IPCOM000090690D
Original Publication Date: 1969-Jun-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Tjon Pian Gi, WE: AUTHOR [+2]

Abstract

The system is for detecting and recording program loops of unknown lengths. A program loop is characterized by a series of executed codes and is terminated by a branch instruction to a return point at the beginning of the loop.

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Program Loop Detector

The system is for detecting and recording program loops of unknown lengths. A program loop is characterized by a series of executed codes and is terminated by a branch instruction to a return point at the beginning of the loop.

Branch instruction detector 10 detects any number of available branch instructions by providing a signal to single-shot 13. This provides a pulse on lines 14 and 24 indicating that a branch is taken. A 16-stage ring 17 has sequence detectors 18a...18n respectively connected to ring 17 outputs through respective circuits 19a...19n. The ring is stepped from one stage to the next by a pulse on line 21 everytime a sequential instruction is executed, nonbranch or branch not taken. As soon as a branch instruction is sensed by detector 10, a pulse on line 24 is provided to all control circuits 19. One circuit 19 is currently enabled by the active ring output indicating to where ring 17 has been stepped. This circuit 19 uses the pulse on line 24 to step its sequence detector 18. All other sequence detectors are reset by the same pulse on line 24. Ring 17 is also reset to its zero position by the same single-shot pulse after it is delayed through delay circuit 15.

Each circuit 19 includes And's 26 and 27 which have inputs connected to line
24. Inverter 28 has an input connected to the respective ring position. Its true input connects to And 27 and its inverted output to And 26. Thus, And 26 provides a reset output pulse to its...