Fujitsu Corporation

Fujitsu Automation Limited

Hitachi, Ltd.

Nippon Telegraph and Telephone Public Corporation

Fujitsiu Limited

Minoru Saitoh

Hiroaki Komatsu

Toshihide Sasaki

Hiroshi Tsukamoto

Minoru Hiroshima

Shigeru Yoshizawa

Atsushi Asano

Nobuo Saito

Hiroshi Suehiro

Akiko Satoh

Hideo Arai

Keisuke Mise

Michinori Yajima

Data in a data base that describe a logic circuit are converted to a simulation model, and simulations are performed based on them. When it is desired to change a part of the circuit while a simulation is in progress, a tentative correction is made by directly changing the simulation model without entering logics to the data base again. Simulation is continued based on the changed simulation model, then, after the action has been confirmed, the contents of the change are reflected on the data base. In this way, a circuit can easily be changed while simulation is in progress.

Logic simulation system and method

A buffer circuit comprises a storage unit for storing input data, a control unit for controlling an output of input data to an external circuit either directly or via the storage unit by writing the input data into the storage unit and then reading the input data out therefrom, and a selection unit for selecting for an output either the input data for direct output or the input data written into and then read out from the memory unit. The control unit determines whether input data exist and whether the external circuit is ready for receiving output data, and controls, based on a result of the determination, the output of the selection unit to the external circuit.

Buffer circuit with control device to directly output input data or to

The present invention is a simulation apparatus which can shorten the transmission and reception time of events, and unify simulation models to make it possible to use the same language expression as that for an ordinary model to express a real chip. The simulation apparatus comprises a real chip simulation section for carrying out simulation for a portion having an unknown internal logic by using a real chip, a logic simulation hardware section for carrying out simulation for a portion whose internal logic is described, and a high speed dedicated network for transferring event data between the real chip simulation section and the logic simulation hardware section. The simulation apparatus can be applied to hardware accelerators used in logic timing simulation in the field of CAE.

Simulation apparatus

In a logic simulation apparatus formed of dedicated hardware for simulating a logic operation of at least one logic circuit, and connected to at least one host computer, the apparatus includes: a plurality of clusters, each cluster including at least a communication network and a plurality of processor elements connected each other through the communication network; and an upper communication network for connecting among clusters. The host computer is connected to at least one cluster, and the connection configuration among the plurality of clusters is changeable in accordance with the size of the logic operation to be simulated under instructions of configuration change generated by the host computer. The apparatus further includes an error analysis system for the simulation process.

Logic simulation apparatus based on dedicated hardware simulating a

A simulation apparatus and method for a logic circuit including a multi-port RAM effects simulation by provisionally representing input and output ports by use of a plurality of memory primitives and effecting the operation equivalent to the operation of the multi-port RAM. The address, data input and write enable terminals of input side memory primitives are supplied with write addresses, data inputs and write enable signals, respectively, and the chip select terminals thereof are supplied with '0' from a logic primitive. The write enable signals are also supplied to an AND logic primitive. The address terminals of output side memory primitives are supplied with respective read addresses, the data input terminals thereof are supplied with an output of the AND logic primitive, the chip select terminals thereof are supplied with '0' from a logic primitive, and the write enable terminals thereof are supplied with '1' from a logic primitive. Data outputs are derived from the respective output side memory primitives.

Method and apparatus for logic simulation of logic system including

Event packets are input to an event handler both in a scheduling phase and in a dispatching phase of an event scheduler. In the scheduling phase, EVCNT of a device of an occurring event is counted up by 1, and in the dispatching phase, EVCNT of a device of a mature event is counted down. In the dispatching phase multiple events are detected based on the EVCNT. If an old status of the top event of the multiple events is equal to a current status of the device, it is decided that event-outstripping has occurred, and events are cancelled. If the old status is not equal to the current status, it is decided that a glitch occurs, and events are modified according to a given mode value. Since the event handler can be implemented by a simple combination logic unit, acceleration performance of a logic simulation accelerator is not adversely affected.

Detection of event-outstripping and glitches in hardware logic simulator

A shift register type memory having major and minor loops, wherein the number of bits of the major loop is large enough to permit data of at least two blocks to simultaneously exist in the major loop when one block is constituted of data of bits the number of which is equal to the number of the minor loops, and wherein before a particular block having been transferred out from the minor loops to the major loop is again transferred in to the minor loops after travelling round the major loop, the next block is transferred out from the minor loops to the major loop.

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Kawasaki, Japan

Minoru Saitoh