Amdahl Corporation

Jeffrey A Thomas

Joseph A Petolino

Christopher D Finan

Michael DeMar Taylor

Theodore S Robinson

Ajay K Shah

Robert A Ertl

Kevin L Daberkow

James P Millar

Michael J Begley

Daniel Carl Sobottka

Gary A Woffinden

Mark Semmelmeyer

Allan J Zmyslowski

Robert M Maier

Richard J Tobias

Jeffrey T Isozaki

Harold F Christensen, Jr

Shen H Wang

Mehrzad Kasrazadeh

Harold F Christensen,Jr

Jack Chen

The computer system architecture utilizes the ability to actively force a ghost line state in management of a split instruction and operand cache associated with an instruction unit with respect to a secondary system integrity cache tag store separately managed by a system controller. The split instruction and operand cache and the system controller tag store permit the management of multiple copies (line-pairs) of a memory line by storing address tag line pair state information with respect to each memory line present in the split-cache to allow determinations of whether and where the respective memory line pair members reside upon access of any one member. The architecture further includes a data path selector for transferring operand data to either the instruction or operand data cache buffers, or both, depending on whether the operand buffer destination is a memory line that is a member of a line pair. A ghost line state is forced whenever a modified memory line, existing as a member of a line pair is to be stored into the operand cache and a concurrent storage of the modified memory line in the instruction cache cannot be performed.

Microprocessor system private split cache tag stores with the system tag

A computer system architecture implementing multiple central processing units, each including a split instruction and operand cache, and that provides for the management of multiple copies (line pairs) of a memory line through the use of a line pair state is described. Systematic management of memory lines when transferred with respect to instruction and operand data cache memories allows the integrity of the system to be maintained at all times. The split cache architecture management determines whether a memory line having a first predetermined system address is present within both the instruction and operand cache memories or will be upon move-in of a memory line. Address tag line pair state information is maintained to allow determinations of whether and where the respective memory line pair members reside. The architecture implements the management of the line pairs on each transfer of a memory line to any of the split caches of the system. A line pair is allowed to exist whenever the same memory line exists in the same relative location in each of the instruction and operand cache buffers of a single central processor. The architecture further includes a data path selector for transferring operand data to either the instruction or operand data cache buffers, or both, depending on whether the operand buffer destination is a memory line that is a member of a line pair.

Computer system architecture implementing split instruction and operand

An apparatus and method for use in improving cache storage unit utilization during an interlock of an instruction pipeline generates a control signal during one cycle of the interlock if the interlocked instruction may require storage unit management work. In response to the control signal, selector control logic in the storage unit generates a priority signal indicating the interlocked instruction for selection by the storage unit for processing. In response to the control signal and the priority signal, the cache management logic is used during the interlock on the interlocked instruction to prepare for supplying needed data when the interlock is released.

Apparatus and method for improving cache access throughput in pipelined

A queue buffer used for the controlled buffering and transferal of data between a cache memory of a central processor unit and a mainstore memory unit. The queue buffer of the present invention preferably includes a buffer memory for the queued storage of data and a controller for directing the nominally immediate acceptance and storage of data received direct from a cache memory and for the nominally systematic background transfer of data from the queue buffer to the mainstore memory unit. This nominal prioritization of memory transfers with respect to the queue buffer memory allows data move-in requests requiring data from the main storage unit to proceed while required move-out data is moved from a cache memory immediately to the buffer queue memory.

Computer system architecture employing cache data line move-out queue

In a data processing system including a pipelined instruction execution unit and a pipelined high speed cache, a storage queue consisting of a set of FIFO registers and associated support logic handles transfer of data from the pipeline instruction execution unit to the high speed cache. When a store request flow from the instruction execution pipeline is forwarded to the high speed cache, instead of placing the data directly into the high speed cache, the starting address, length of store and data to be stored are placed into one of the store queue registers. The instruction execution unit sees the store request as completed and continues processing even though data has not been physically placed in the high speed cache. The write to the high speed cache is finished in the background at a later time during an unused storage pipeline cycle in the high speed cache.

Monolithic semi-custom IC having standard LSI sections and coupling gate

In a pipeline data processing machine having a first unit for execution of instructions running according to a first pipeline and a second unit for storing data from a plurality of ports running according to a second pipeline, the first unit having a result register for holding results including data and address information of a flow of the first pipeline, the present invention provides an apparatus for transferring results in the result register to the second unit. A plurality of registers connected to the result register, each storing the result from at least one flow of the first pipeline and storing control information is provided. Further, a controller in communication with the second unit and the plurality of ports responsive to the control information and a flow of the second pipeline is included for selecting one of the plurality of ports in a first-in, first-out queue as a port to the second unit and for updating the control information.

Cache storage queue

Bypassing of data from a main storage unit to an instruction and operand processing unit around an intermediate storage unit improves performance in a data processing system. The instruction and operand processing unit supplies requests for operands to the intermediate storage unit or cache. If the line is missing from the cache, the request operand is retrieved from the main storage unit. A bypass data path is connected between the main storage unit, prior to error detecting means in the cache, and the instruction and operand processing unit for transferring requested operands to the instruction and operand processing unit directly. Control, coupled to receive requests for operands and to the instruction and operand processing unit, signals the instruction and operand processing unit to receive the requested operands from the bypass data path when the data includes a requested operand.

Cache move-in bypass

The present invention provides an apparatus for reporting errors in data stored in a memory apparatus of a data processor, comprising: first means for storing multiple digital first signals; second means for storing said multiple digital first signals and adapted for storing at least one digital second signal; third means for transmitting said multiple digital first signals substantially from said first means to said second means; fourth means for providing said at least one digital second signal, in the course of the transmitting of said first signals by said third means, in response to an occurrence of one or more errors in one or more of said multiple digital first signals; fifth means for transmitting said multiple digital first signals substantially from said second means to said first means; and sixth means adapted for receiving said at least one digital second signal in the course of the transmitting of said multiple digital first signals by said fifth means and for providing at least one third signal in response to an occurrence of said at least one digital second signal. ECC codes are generated and applied over a plurality of distinct checking blocks in each flow of data in order to minimize delays in the move-in data path, and bypass data paths are provided such that a flow may bypass all error checking and correcting circuitry and cacheing apparatus between the main storage array and the CPU.

Error detection and correction scheme for main storage unit

A data processing machine includes an instruction unit that decodes and organizes a flow of instructions for processing data. In response to certain instructions, the instruction unit generates requests for storage unit resources. In addition, results generated in the instruction unit in response to certain instructions are supplied for storage in the storage unit. The storage unit selects in response to priority logic from completing requests for storage unit resources, including a high speed cache storing data, and a plurality of storage ports for transferring data from the result register to the high speed cache. Each of the storage ports generates requests for access to the high speed cache to transfer the data stored in the respective store ports to the cache. Storage unit priority is determined in part by predicting the fullness of the storage ports.

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Cupertino, CA, United States of America

Jeffrey A Thomas