Kabushiki Kaisha Toshiba

Yasuo Unekawa

Tadahiro Kuroda

Kenji Sakaue

Masataka Matsui

Tetsu Nagamatsu

Fumiyuki Yamane

Yuichi Miyazawa

Ryouichi Bandai

It is an object of the present invention to provide a data switching method capable of impartially selecting a plurality of input ports by a simple circuit configuration. The data switching method according to the present invention includes an up-counter, a down-counter, a counter selecting circuit for selecting either of a counted value by the up-counter or a counted value by the down-counter, a port selecting circuit for selecting one of a plurality of input ports based on an output from the counter selecting circuit, and a buffer for accumulating a packet supplied from the input port selected by the port selecting circuit. The port selecting circuit alternately selects the up-counter and the down-counter to switch the ascending order and the descending order of the import priority of the input ports at every time the packet is imported, thereby impartially selecting each of the input ports.

Data switching apparatus and data switching method

A semiconductor memory includes a memory cell including inverters (IN1, IN2), control transistors (T3, T4) that control the potential of a ground side terminal (N3) connected to the memory cell, and transfer transistors T1 and T2 that control transfer of data from bit lines (BL, /BL) to the memory cell. In writing data, the control transistors raise the potential of the ground side terminal (N3) to be higher than the ground potential by a predetermined potential. After the transfer transistors transfer data having a potential difference smaller than a potential difference between the power supply potential and the ground potential from the bit lines (BL, /BL) to the memory cell, and cause the memory cell to hold the data, the potential of the ground side terminal (N3) is decreased to the ground potential to write data. Since data written in the memory cell suffices to have a potential difference smaller than the potential difference between the power supply potential and the ground potential, the time required to drive the bit line having a large load capacitance is shortened, the power consumption is decreased, and the power consumption necessary for writing data in the memory cell is reduced.

Static random access memory including potential control means for

The proposed address generating circuit of a shared-buffer type ATM (asynchronous transfer mode) switch adopts such an address management method that the ports multi-plexed by time division for each input link can be switched to each output link through time division multiplexing. The address generating circuit of shared-buffer type ATM switch used for an ATM switching system comprises a plurality of address generating units (4) each for storing an address, port data and output link data of a cell stored in each shared buffer in time series manner; two port pointer registers (8a, 8b, 8c, . . . ) for storing data indicative of a current output port for each output link; and a port list table (9) for storing data of ports accommodated in each output link.

ATM switch address generating circuit

The proposed address generating circuit of an ATM (asynchronous transfer mode) switch can support a plurality of service classes by use of a single LSI under such a management that the cell buffers are divided for each service class. That is, an address generating circuit of shared buffer type ATM switch for an ATM switch system comprises a plurality of address generating units (5) each for storing a routing tag indicative of a cell output port, an address, and class data indicative of a service class of each of data cells stored in shared cell buffers. When data cells are inputted to and outputted from the shared cell buffers, the routing tags and the addresses of the address generating units (5) each having matching cell class data are selected and used.

A timeout process circuit for performing a timeout detection process incorporated in a receiver, having a timer for incrementing time data indicating a current time, a memory including data table to store a reception time of the cell most recently received by the receiver, a register for storing a timeout value indicating a maximum permitted time interval of cell reception, a controller for reading out the reception time stored in the data table the controller receiving the timeout detection start signal from the timer, an adder for adding the reception time from the data table and the timeout value stored in the first register means, a comparator for comparing the result of the addition by the adder with the time data from the timer, and a decision circuit for receiving the comparison result from the comparator and deciding whether or not the cell of the frame in the reassembly is a timeout based on the comparison result. In the timeout process circuit, the reception time of the cell is stored in the data table when the cell is received by the receiver.

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Yokohama, Japan

Yasuo Unekawa