Digital Equipment Corporation

Lloyd I Dickman

William D Strecker

A central processor for use in a data processing system that is adapted for processing sequences of characters. Information identifying a string of characters to be examined, including the memory location for the first character in the sequence and the total number of characters in the sequence, is placed in working registers of the central processor. Other working registers in the central processor receive information corresponding to a predetermined characteristic, which may be a specific character or information identifying another character string. One of several character string instructions then can be processed. In response to a typical character string instructuion, the central processor retrieves each character from the memory and compares it with the predetermined characteristic. Processing continues until either the predetermined characteristic is detected or all the characters in the character string are examined. During processing, the central processor controls an arithmetic-logic condition code during each comparison. When the processing terminates, the condition code indicates whether the character string contained the predetermined characteristic.

Central processor with instructions for processing sequences of

A central processor for use in a data processing system that is adapted for processing sequences of characters. Information identifying a string of characters to be examined, including an initial memory location of the first character in the sequence and the total number of characters in the sequence, is placed in working registers of the central processor. Other working registers in the central processor receive information corresponding to a predetermined characteristic, which may be a specific character or information identifying another character string. One of several character string instructions then can be processed. In response to a typical character string instruction, the central processor performs the function defined by the instruction in an iterative fashion as the central processor retrieves successive characters from a memory. During each iteration the central processor tests to determine whether any interruption conditions exist. If one does, the central processor suspends further operations in response to the instruction and services the interruption. When the interruption has been serviced, the central processor again retrieves the suspended instruction and begins processing the character string with the character which would have been processed if the interruption had not occurred.

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Sudbury, MA, United States of America

Lloyd I Dickman