The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 08, 1985
Filed:
May. 22, 1981
Lawrence H Katz, Oregon City, OR (US);
Douglas M Wells, Chapel Hill, NC (US);
Michael S Richmond, Pittsboro, NC (US);
Richard A Belgard, Saratoga, CA (US);
Walter A Wallach, Jr, Raleigh, NC (US);
David H Bernstein, Ashland, MA (US);
John K Ahlstrom, Mountain View, CA (US);
John F Pilat, Raleigh, NC (US);
David A Farber, Durham, NC (US);
Richard G Bratt, Wayland, MA (US);
Data General Corporation, Westboro, MA (US);
Abstract
A method for executing call and return instructions in a digital computer system operating under control of microcode. The microcode may specify calls to and returns from sequences of microinstructions. A call microinstruction sequence corresponds to the call instruction. The call microcode in turn calls other microinstruction sequences for deriving pointers representing the location of the called procedure and of arguments from operands in the call instruction. As the call microcode obtains each argument pointer, it places the pointer on the stack. After it has obtained all of the argument pointers, it passes the pointer to the called procedure and a pointer to the argument pointers to a general call microinstruction sequence. That microinstruction sequence locates the called procedure, makes a new frame including the argument pointers, and saves the state necessary to resume execution of the call microinstruction sequence itself. It then obtains the state necessary to commence execution of the called procedure and causes execution of that procedure to commence. The microcode corresponding to the return instruction restores both the state necessary to resume execution of the calling procedure and the state necessary to resume execution of the call microinstruction sequence. When it resumes execution, the call microinstruction sequence completes the return operation.