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Fujitsu, NEC and Toshiba Agree on Common Specifications for Next-Generation Pseudo SRAM User Interface for Mobile Applications

14 March, 2002

Fujitsu Limited
NEC Corporation
Toshiba Corporation

Tokyo, March 14, 2002 -- Fujitsu Limited, NEC Corporation and Toshiba Corporation announced today that they have reached an agreement on common specifications for the next generation of Pseudo Static Random Access Memory (PSRAM) *1 devices. The new common specifications for next-generation mobile Pseudo SRAM user interface emerged from discussions among the three companies that began in October of last year.

Each of the three companies will independently manufacture and market PSRAM products based on the common specifications, with product introduction expected to begin in the second half of fiscal 2002.

Because the new specifications standardize the packaging and pin layout for the PSRAM, customers will benefit from a uniform design format, eliminating the need to customize designs for each product. This advantage will help shorten the design cycle and dramatically improve design efficiency. Also, since the three companies are using common specifications, they can also act as alternative sources for each other, helping to ensure a stable market supply.

Recent performance enhancements of cellphones and other mobile equipment, such as PDAs, have created demand for more onboard memory. In the past, this "working memory" came in the form of low-power SRAM, but because of the difficulty of scaling up low-power SRAM to handle large densities, suppliers were unable to respond rapidly to the market need for higher densities. Instead, high-density PSRAM, which can readily scale up to 16 Mbit or more, is now being widely used. Also, high-speed needs are rapidly expanding in cellphone and PDA applications, and PSRAM is responding to it as well.

PSRAM had been designed with an emphasis on compatibility with SRAM, but each manufacturer has developed its own product specifications, with different pinouts, limiting compatibility. This has also caused problems for stacked multi-chip packages (MCPs) that contained PSRAM chips.

The common specifications resolve the compatibility problem by defining memory densities, supply voltage ranges, control-pin names, some functions, packaging and other user-interface specifications.

Specifically, the new specifications cover:
-Supply voltage range
-Control pin names
-Truth table*2
-Partial refresh*3 function (refresh size and corresponding base address assignment)
-Page mode function (page length*4 and corresponding addressing)
-Mode register*5 defaults
-Mode-register setting method
-Power-on sequence*6
-Packaging: For 64 Mbit and less, 48-ball FBGA (0.75 mm pitch); 128 Mbit and higher, under consideration.

In September 1998, the three companies promulgated common specifications for stacked MCPs that include both flash memory and SRAM. These specifications will be expanded to incorporate the new common spec for next-generation PSRAM, forming the basis for common specifications for next-generation PSRAM, forming the basis for common specifications for next-generation MCPs that include PSRAM. This development will bring the benefits of design format efficiencies and a stable market supply to MCP customers as well.


*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 highly 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 operations 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:Page length
Page mode is a technique to improve a device's memory-access performance. In paged mode, an initial access address is given, and then by toggling a certain address pin, data can be read rapidly and continuously, a certain number of words at a time, from that initial address. The "page length" is that number of words.
*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 initializes 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

Fujitsu is a leading provider of Internet-focused information technology solutions for the global marketplace. Its pace-setting technologies, best-in-class computing and telecommunications platforms, and worldwide corps of systems and services experts make it uniquely positioned to unleash the infinite possibilities of the Internet to help its customers succeed. Headquartered in Tokyo, Fujitsu Limited (TSE:6702) reported consolidated revenues of 5.48 trillion yen for the fiscal year ended March 31, 2001. Internet:

About NEC

NEC Corporation (NASDAQ: NIPNY) (FTSE: 6701q.l) is a leading provider of Internet solutions, dedicated to meeting the specialized needs of its customers in the key computer, network and electron device fields through its three market-focused in-house companies: NEC Solutions, NEC Networks and NEC Electron Devices. NEC Corporation, with its in-house companies, employs more than 150,000 people worldwide and saw consolidated net sales of 5,409 billion Yen (approx. US$43 billion) in the fiscal year ended March 31, 2001. For further information, please visit the NEC home page 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, LCDs and other electronic devices. Toshiba has 188,000 employees worldwide and annual sales of over US$47 billion. Visit Toshiba's website at

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