International Business Machines Corporation

John Wallace Goetz

Stephen William Mahin

Stephen W Mahin

John Michael Keaty

John J Bergkvist

A microprocessor which supports two distinct instruction-set architectures. The microprocessor includes a mode control unit which enables extensions and/or limitations to each of the two architectures and controls the architectural context under which the microprocessor operates. The control unit controls memory management unit (MMU) hardware that is designed to allow address translation to take place under the control of a mode bit so that the translation mechanism can be switched from one architecture to another. A single MMU translates addresses of the two distinct architectures under control of the mode bit which is also used to simultaneously inform instruction decode which architecture is being used so that instructions are properly decoded. The MMU is also capable of mapping the address translation of one architecture onto that of the other so that software written for both architectures may be multi-tasked under the control of a single operating system.

Microprocessor with an architecture mode control capable of supporting

A computer system supports control transfers between two architectures with different address ranges and/or different methods of calling programs which involve passing parameters, stack pointers and return addresses. Control is transferred between the architectures through a control transfer mode bit.

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Jericho, VT, United States of America

John Wallace Goetz