Fujitsu Corporation

Kenji Shirasawa

Koichi Kuroiwa

Hideyuki Iino

Hiroyuki Fujiyama

Shinichi Utsunomiya

Noriko Kadomaru

Makoto Miyagawa

Hiromasa Takahashi

Seiji Suetake

Koichi Hatta

Tatsuya Nagasawa

Masaharu Kimura

A memory accessing device and method, in a data processing system which has pipelines, for correctly associating prefetched addresses from an address bus with corresponding prefetched data from a data bus, when sending data to and receiving data from an external memory. The memory accessing device has a condition determining device determining pipeline control conditions based on pipeline information and address information; a number-of-stages selecting device selecting the number of pipeline stages based on pipeline activation conditions and the pipeline control conditions; and a valid data detecting device detecting valid data positions in the prefetched data based on the number of pipeline stages selected and correctly associating the valid data positions in the prefetched data with the prefetched addresses. Additionally, a data input/output unit performs an arithmetic operation on data transferred from an external memory to a vector register, wherein the result of the arithmetic operation, upon completion, is transferred from the vector register to the external memory for storage. The data input/output unit has a data holding unit storing m-bit data units and rearranges exactly in the original order n pieces of m/n-bit data when n pieces of m/n-bit data are loaded from an external memory and then stored back into the external memory.

Data processing system, memory access device and method including

A slave processor for executing for example a vector operation is connected to a master processor. A vector length for a vector operation set to the slave processor can be changed without intervention of the master processor. When the master processor activates the slave processor, the slave processor outputs a busy signal immediately (at most one cycle later). The master processor reads the value of a busy register representing a busy/ready status of the slave processor in a slave access cycle at highest speed (in two cycles at most). Regardless of whether the master processor and the slave processor was designed as series products or general purpose products, they can be effectively connected.

Data processing apparatus for executing a vector operation under control

A memory accessing device is connected to a central processing unit and a memory unit via a common bus. The memory accessing device accesses the memory unit independently of the central processing unit. The device includes an address generating unit for generating an address, an address control unit for outputting the generated address to the bus, and a control unit for controlling the address control unit to suspend or terminate memory access controlled in an address pipeline mode when the memory accessing device internally or externally issues a request for the suspension or the termination of the memory access controlled in the address pipeline mode. The control unit terminates or suspends the memory access when it receives a request internally or externally of the memory accessing device for the suspension or the termination of the memory access.

Memory accessing device for a pipeline information processing system

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Kawasaki, Japan

Kenji Shirasawa