Method of performing a call operation in a digital data processing system having microcode call and return operations

US4493027A · kind A · utility

Assignee

• Data General Corporation · US

Inventors

• Lawrence H. Katz · Oregon City, US
• Douglas M. Wells · Chapel Hill, US
• Michael S. Richmond · Pittsboro, US
• Richard A. Belgard · Saratoga, US
• Walter A. Wallach, Jr. · Raleigh, US
• David H. Bernstein · Oakland, US
• John K. Ahlstrom · Mountain View, US
• John F. Pilat · Raleigh, US
• David A. Farber · Ojai, US
• Richard G. Bratt · Wayland, US

Key dates

• Filing date: May 22, 1981
• Grant date: Jan 8, 1985
• Expiry date: May 22, 2001

Classification

• Technology area (CPC G): Physics
• CPC primary: G06F9/4484
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

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 calli…