Hitachi, Ltd.

Hitachi Process Computer Engineering, Inc.

Hitachi Computer Electronics Co., Ltd.

Ichiharu Aburano

Kazushi Kobayashi

Koichi Okazawa

Tetsuya Mochida

Hitoshi Kawaguchi

Koichi Kimura

Takeshi Aoki

Takanori Ishikawa

A processor bus linked with at least a processor, a memory bus linked with a main memory, and a system bus linked with at least an input/output device are connected to a three-way connection control system. The control system includes a bus-memory connection controller connected to address buses and control buses respectively of the processor, memory, and system buses to transfer address and control signals therebetween. The control system further includes a data path switch connected to data buses respectively of the processor, memory, and system buses to transfer data via the data buses therebetween depending on the data path control signal.

Bus system for use with information processing apparatus

A processor bus linked with at least a processor, a memory bus linked with a main memory, and a system bus linked with at least an input/output device are connected to a three-way connection control system. The control system includes a bus-memory connection controller connected to address buses and controL buses respectively of the processor, memory, and system buses to transfer address and control signals therebetween. The control system further includes a data path switch connected to data buses respectively of the processor, memory, and system buses to transfer data via the data buses therebetween depending on the data path control signal.

A processor bus linked with at least a processor, a memory bus linked with a main memory, and a system bus linked with at least an input/output device are connected to a three-way connection control system. The control system includes a bus-memory connection controlling connected to address buses and control buses respectively of the processor, memory, and system buses to transfer address and control signals therebetween. The control system further includes a data path switch connected to data buses respectively of the processor, memory, and system buses to transfer data via the data buses therebetween depending on the data path control signal.

Multiple bus system using a data transfer unit

In a computer system having an address converter for DMA (direct memory access), an address conversion apparatus in which a memory area to be accessed by the DMA can be accessed at high speed from a CPU. A 'DMA address conversion area' is defined in a memory space, and address conversion means in the mode of accessing the DMA address conversion area is so constructed that, when the area has been accessed from the CPU, a physical address is generated in accordance with the address conversion routine of the DMA address conversion means or converter, so as to access a main storage. The memory area to be accessed by the DMA can be quickly accessed from the CPU without requiring such an operation as especially accessing the control ware of the address converter or producing the physical address under the management of a program run on the CPU.

Address conversion apparatus accessible to both I/O devices and

An information processing system includes a central processing unit, a main storage, a main storage controller for controlling the main storage, a cache memory having a content of at least one part of addresses stored in the main storage, at least one DMA controller which is capable of referring to the main storage and a DMA address translation unit for translating a logical address outputted from the DMA controller into a physical address for referring to the main storage. The DMA address translation unit has a flag representing whether or not the cache memory is referred to on DMA. The main storage controller performs either of reference to the cache memory or direct reference to the main storage based upon the flag on DMA.

Growing community of inventors

Hitachi, Japan

Ichiharu Aburano