Data General Corporation

Douglas M Wells

Richard G Bratt

Lawrence H Katz

John F Pilat

David H Bernstein

Thomas M Jones

Craig J Mundie

Steven J Wallach

Stephen I Schleimer

Gerald F Clancy

Richard A Belgard

Walter A Wallach, Jr

Brett L Bachman

Edward S Gavrin

Michael S Richmond

John K Ahlstrom

David A Farber

Eric C Hamilton

Ronald H Gruner

J Theodore Compton

A data processing system having a flexible internal structure, protected from and effectively invisible to users, with multilevel control and stack mechanism and capability of performing multiple, concurrent operations, and providing a flexible, simplified interface to users. The system is internally comprised of a plurality of separate, independent processors, each having a separate microinstruction control and at least one separate, independent port to a central communications and memory node. The communications and memory node is an independent processor having separate, independent microinstruction control and comprised of a plurality of independently operating, microinstruction controlled processors capable of performing multiple, concurrent memory and communications operations. Addressing mechanisms allow permanent, unique identification of information and an extremely large address space accessible and common to all such systems. Addresses are independent of system physical configuration. Information is identified to bit granular level and to information type and format. Protection mechanisms provide variable access rights associated with individual bodies of information. User language instructions are transformed into dialect coded, uniform, intermediate level instructions to provide equal facility of execution for all user languages. Operands are referred to by uniform format names which are transformed, by internal mechanisms transparent to users, into addresses.

Digital data processing system method for making a general call

A digital data processing system using process synchronization techniques which comprise processing await logic for suspending the execution of a program controlled by a process, virtual processor await logic for performing an await operation at the virtual processor level and for temporarily inhibiting the loading of state items for the execution of the program, virtual processor advance logic for performing an advance operation at the virtual processor level to cease the inhibition of the loading of such state items, and process advance logic for causing the processor of the system to resume execution of the suspended program which is under control of the process.

Digital data processing system

A digital computer system in which data storage is referred to by a descriptor comprising an object number denoting a variable-length block of storage, an offset indicating how far into that block a desired data item begins, and a length field denoting the length of the desired data item. Separate means exist for manipulating each of the three descriptor portions, thus facilitating repetitive operations on related or contiguous operands. Various levels of microcode control are included. Each level of microcode control has its own stack, facilitating interrupts between levels. Stacks are duplicated in 'secure stacks' in memory to protect against loss of state data from the stacks.

Digital data processing system with tripartite description-based

A digital data processing system has a memory organized into objects containing at least operands and instructions. Each object is identified by a unique and permanent identifier code which identifies the data processing system and the object. The system utilizes unique addressing mechanisms the addresses of which have object fields, offset fields and length fields for specifying the location and the total number of bits of an addressed object. The system uses a protection technique to prevent unauthorized access to objects by users who are identified by a subject number which identifies the user, a process of the system for executing the user's procedure, and the type of operation of the system to be performed by the user's procedure. An access control list for each object includes an access control list entry for each subject having access rights to the object and means for confirming that a particular active subject has access rights to a particular object before permitting access to the object.

Data processing system having addressing mechanisms for processing

A digital data processing system has a memory organized into objects containing at least operands and instructions. Each object is identified by a unique and permanent identifier code which identifies the data processing system and the object. The system further uses multilevel microcode techniques for controlling sequences of microinstructions and for controlling the interval operations of the processor. The system uses a protection technique to prevent unauthorized access to objects by users who are identified by a subject number which identifies the user, a process of the system for executing a user's procedure, and the type of operation of the system to be performed by the user's procedure. An access control list for each object includes an access control list entry for each subject having access rights to the object and means for confirming that a particular active subject has access rights to a particular object before permitting access to the object. The system also includes stacks for containing information relating to the current state of execution of the system.

Data processing system using object-based information and a protection

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.

Method of performing a call operation in a digital data processing

A data processing system having a flexible internal structure, protected from and effectively invisible to users, with multilevel control and stack mechanisms and capability of performing multiple, concurrent operations, and providing a flexible, simplified interface to users. The system is internally comprised of a plurality of separate, independent processors, each having a separate microinstruction control and at least one separate, independent port to a central communications and memory node. The communications and memory node is an independent processor having separate, independent microinstruction control and comprised of a plurality of independently operating, microinstruction controlled processors capable of performing multiple, concurrent memory and communications operations. Addressing mechanisms allow permanent, unique identification of information as objects and an extremely large address space accessible and common to all such systems. Addresses are independent of system physical configuration and, as particularly described with reference to the invention herein, identify locations of object information to be accessed by utlizing address formats which comprise an object field, offset field and a length field so that information can be identified to bit granular level and to information type and format. Arithmetic logic unit (ALU) means, also as particularly described with reference to the invention herein, include general register means having three vertically oriented parts for storing such respective fields. Such ALU means further include an ALU microinstruction stack means having at least one microinstruction stack frame for storing the state of execution of a microinstruction. A memory microinstruction stack is provided to store a plurality of microinstruction stack frames so that microinstruction stack frames can be transferred between the ALU and the memory microinstruction stacks. Protection mechanisms provide variable access rights associated with individual bodies of information. User language instructions are transformed into dialect coded, uniform, intermediate level instructions to provide equal facility of execution for all user languages. Operands are referred to by uniform format names which are transformed, by internal mechanisms transparent to users, into addresses.

Digital data processing system using unique ALU register files and

Systems and method for resolving unresolved pointers in digital computer systems. In unresolved pointers, addresses are represented by means of data items from which the addresses may be derived. The unresolved pointer is resolved when the represented address is derived from the data items. One such system includes the unresolved pointers and procedures for resolving the unresolved pointers in the digital computer system's memory and apparatus in the digital computer system's process which operates under control of pointer translation microcode to translate pointers into represented addreses and under control of call-return microcode for invoking procedures from microcode. The pointer translation microcode responds to an unresolved pointer by causing the call-return microcode to invoke the procedures for resolving the unresolved pointer. Using the data items in the unresolved pointer, the procedures derive the represented address and return it to the pointer translation microcode. Another such system includes an associated address table which associates an unresolved pointer with its represented address and associated pointer fault procedures. Here, the pointer translation microcode responds to the unresolved pointer by searching the table for an entry containing the unresolved pointer. If there is such an entry, the pointer translation microcode obtains the represented address from the table. If there is not, the pointer translation microcode causes the call-return microcode to invoke the associated pointer fault procedures, which resolve the unresolved pointer and place the represented address in the associated address table. A third such system combines the first two systems. Details of the systems and methods of resolving unresolved pointers are also disclosed.

System for resolving pointers in a digital data processing system

An improved system for performing call and return operations in a computer system in which every call and return operation changes the program counter and the frame pointer but some call and return operations change other state. Included in the state which may change in the computer system of the present invention is addresses used in calculating other addresses, an identifier specifying which instruction set the processor is executing, and protection state which determines what data may be accessed during execution of a procedure. In the system, the state saved and restored in the call and return operations is divided into basic state saved and restored on every call and return and extended state saved and restored on only some calls and returns. The frame associated with an execution accordingly contains either saved basic state or saved basic state and saved extended state. The frame further contains a frame type item in each frame which specifies whether it contains only basic state or both basic and extended state. There are two call instructions and a single return instruction. The system responds to one call instruction, the neighborhood call instruction, by saving and setting only basic state; it responds to the other, the general call instruction, by saving and setting both basic state and extended state, and if necessary, saving and setting protection state. The processor responds to the single return instruction and the frame type specifier by restoring the state specified in the frame type specifier.

System for performing call and return operations

An improved system for saving state during a call operation and restoring state during a return operation in a computer system in which different call and return operations require the saving and restoring of different amounts of state. The components of the system are call instructions whose operation codes specify the amount of state to be saved, frames which contain either basic state saved on every call operation and restored on every return operation or basic state and extended state saved only on certain calls and returns, a frame type item in each frame which specifies whether it contains only basic state or both basic and extended state, a single return instruction, state-saving apparatus which is responsive to the different call instructions, and state-restoring apparatus which is resposive to the single return instruction and to the frame type item. When a call instruction specifies that extended state is to be saved, the state saving apparatus responds thereto by saving both basic and extended state and setting the frame type item to indicate that the frame contains both; when a call instruction indicates that only basic state is to be saved, the state saving apparatus saves only basic state and sets the frame type item accordingly. The state restoration apparatus responds to the return instruction by restoring that state specified by the frame type item.

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Chapel Hill, NC, United States of America

Douglas M Wells