Fujitsu Corporation

Fujitsu Microelectronics Limited

Shinkichi Gama

Takeshi Nagase

Tomohiro Hayashi

Yoshihiro Takamatsuya

Yoshiki Okumura

Shogo Shibazaki

Chikahiro Deguchi

Yutaka Sekino

Hideyuki Negi

A memory test is performed by sequentially generating a number of n-bit addresses, whose first to k-th bits (1&#x2266;k&#x2266;n) are all set to one of two values, 0 or 1, and whose (k+1)th to n-th bits are all set to the other one of the two values, for all k's which range from 1 to n; writing first test data to each of the generated addresses in the memory; reading second test data from each of the addresses in the memory; and comparing the first test data with the second test data.

Memory test method and memory test device

A test apparatus includes an up counter, a down counter, a selector that selects either an up counter output from the up counter or a down counter output from the down counter, an inversion circuit that inverts either the counter output selected by the selector or the counter output nonselected by the selector, and a comparison circuit that compares the counter output inverted by the inversion circuit and the other counter output.

Test apparatus, test method, and integrated circuit

An encryption/decryption processing unit performs encryption/decryption processing of data transmitted from a host system, and encryption/decryption processing of key data used for encryption/decryption of the data. A key data buffer temporarily stores encrypted key data. A key data buffer temporarily stores unencrypted key data. An external memory interface controls flash memory attached outside, and reads/writes encrypted key data stored in the key data buffer.

Encryption device

In a storage device for maintaining information when power is OFF and being capable of executing a test process based on test signals, a test terminal inputs the test signals and an instruction part sends a read out instruction for instructing a memory storing secret data to read out data. Moreover, a decoding part decodes whether or not the data read out by the memory in response to the data reading instruction is the secret data stored in the memory and a maintaining part maintains information in a volatile state resulting from the decoding part. Furthermore, a cutting-off part cuts off the test signals input from the test terminal when the maintaining part maintains information indicating that the secret data is stored.

Storage device having secure test process

A memory controlling device is controlled by a CPU to enable information to be read from memory when the memory starts an operation. The memory is capable of retaining data during a power off state and the data is loaded when the memory starts an operation.

CPU controlled memory controlling device for accessing operational information

A buffer access control circuit to access a buffer which is divided into an upper buffer and a lower buffer which are assigned the same address and a memory unit including the buffer access control circuit. The buffer access control circuit includes latch circuits which store data in response to upper and lower buffer access signals, and a first detection circuit which detects whether data latched by the latch circuits match. A modifying circuit inputs data to the first and second latches or inputs inverted data to the first and second latches when one of the upper and lower buffer access signals is generated and the detection circuit detects a match. In this manner, the buffer access control circuit is used to update an address one by one, without the use of a delay circuit when consecutively accessing the upper and lower buffers.

Memory unit and buffer access control circuit for updating an address when consecutively accessing upper and lower buffers

A memory card realizes two interface standards. The memory card includes an input terminal receiving a grounded or open-circuited signal from a host unit when using the memory card in conformance with a first interface standard, and receiving a binary signal from the host unit when using the memory card in conformance with a second interface standard, a first circuit acquiring standard information which indicates the first or second interface standard, from a signal issued from the host unit, a second circuit outputting a high-level voltage when using the memory card in conformance with the first interface standard and outputting a high-impedance signal when using the memory card in conformance with the second interface standard, depending on the standard information acquired by the first circuit, and a resistor coupling an output of the second circuit and the input terminal.

Memory card

A circuit for enabling a chip, usable for both a first device capable of having m chips and a second device having more than m chips, includes a first generation unit which generates a chip-enable signal that includes a bit pattern of m bits for enabling one of the m chips indicated by a chip number, a second generation unit which generates a chip-enable generation signal that is to be decoded into a chip-enable signal of at least 2,bits for enabling one of the more than m chips indicated by the chip number, the chip-enable generation signal including a bit pattern identical to the bit pattern of m bits when the chip number is equal to a specific number, and a selection unit which selects and outputs the chip-enable signal generated by the first generation unit when the circuit is used for the first device, and selects and outputs the chip-enable generation signal generated by the second generation unit when the circuit is used for the second device.

Growing community of inventors

Yokohama, Japan

Shinkichi Gama