Fujitsu, NEC and Toshiba Agree on Common Specifications for “Burst Mode” Pseudo SRAM User Interface

(PRWEB) February 19, 2003

Frankfurt, February 17th, 2003 – Fujitsu, NEC and Toshiba announced today that they have reached an agreement on common specifications for Pseudo Static Random Access Memory (PSRAM) *1 devices that feature burst mode function enabling fast access operation. Each of the three companies will independently manufacture and market PSRAM products based on the common specifications, which are to be called Common Specifications for Mobile RAM (COSMORAM), with product introduction expected to begin in the first half of fiscal 2003.

In September 1998, the three firms promulgated common specifications for stacked multi-chip packages (MCPs) that include both flash memory and SRAM. Then in March 2002, it was announced that the three companies agreed on common specifications for PSRAMs that feature page mode function, forming the basis for a common spec for the page mode PSRAM and stacked MCPs that include the PSRAM. Defining user-interface specifications for high-speed, high-density PSRAMs resolved compatibility problems, thereby allowing customers to efficiently implement the PSRAM devices of all three firms.

The trio of companies has now expanded the agreement to include common specifications for a burst mode PSRAM user interface and the stacked MCPs that house the PSRAMs. Burst mode function enables high-performance operation superior to fast page mode, making it ideally suited to respond to the high-speed processing needs of next-generation cell phones and other mobile equipment, such as PDAs.

Because the specifications for burst mode PSRAM, much like those adopted for page mode PSRAM, standardise the basic electrical properties, packaging and pin layout, customers will benefit from a uniform design format, eliminating the need to customise designs for each product. This advantage will help shorten the design cycle and dramatically improve design efficiency. In addition, since the three companies are using common specs, they can also act as alternative sources for each other, helping to ensure a stable market supply.

The COSMORAM specifications for burst mode PSRAM user interface cover:


Supply voltage range

Control pin names

Truth table*2

Partial refresh*3 function (refresh size and corresponding base address assignment)

Burst mode function (burst length*4 and corresponding addressing)

Mode register*5 defaults

Mode-register setting method

Power-on sequence*6




*1: Pseudo SRAM (PSRAM)

A RAM device that uses a DRAM cell for high density and low bit cost, and that has an asynchronous SRAM external interface to facilitate efficient system design. It is well suited for cellphone applications, where the need for higher density working RAM is rapidly growing as more features and functions are implemented.

*2: Truth table

A table defining how a device’s operation mode correlates to the external signals used to set that mode.

*3: Partial refresh

This is a feature and operating mode for devices in standby mode that limits current consumption. It refreshes some, but not all, of the bits. If the refreshed bits are storing data, the current flow will be greater, but if they are not, the current flow can be kept to a minimum.

*4: Burst length

Burst mode is a technique to improve a device’s memory-access performance. In burst mode, by synchronising clock input from external, data of a certain number can be read out rapidly and continuously with short cycle. The “burst length” is that number of data to be output continuously.

*5: Mode register

An internal register that stores the control code used to govern the device’s operating mode, set externally.

*6: Power-on sequence

A sequence of signal voltages passed through a control pin after the supply voltage is applied to it, which initialises the internal state of the device.

Trademark notice

All product names and proper names mentioned in this document are trademarks or registered trademarks of their respective firms.

About Fujitsu Microelectronics Europe

Fujitsu Microelectronics Europe is a major supplier of semiconductor products to the European and global market. The company’s main business focus is on providing systems solutions to the networking/telecommunications, mobile communications, automotive and multimedia markets.

Fujitsu offers a broad range of semiconductor devices, including telecommunications ICs, RF devices, MPEG encoders and decoders, microcontrollers, graphic display controllers and microprocessors, FCRAMs and Flash memory. The company is also a leader in colour plasma display panels. For more information visit Fujitsu Microelectronics Europe’s website at

About NEC Electronics

NEC Electronics Corporation is a wholly owned subsidiary of NEC Corporation (NASDAQ: NIPNY) (FTSE: 6701q.l), one of the world’s leading providers of Internet, broadband network and enterprise business solutions. NEC Electronics specialises in semiconductor products encompassing advanced technology solutions for the broadband and communications markets, system solutions for the mobile handsets, PC peripherals, automotive and digital consumer markets, and platform solutions for a wide range of customer applications. NEC Electronics Corporation has 24 subsidiaries worldwide including NEC Electronics America, Inc. and NEC Electronics (Europe) GmbH. For additional information, visit the company’s website at

About Toshiba

Toshiba Corporation is a leader in information and communications systems, electronic components, consumer products, and power systems. The company’s integration of these wide-ranging capabilities assures its position as a leading company in semiconductors, displays and other electronic devices. Toshiba has 176,000 employees worldwide and annual sales of over US$ 40 billion. Visit Toshiba’s website at


About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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