NEC Electronics Corporation
Fujitsu, NEC and Toshiba Agree on Common
for "Burst Mode" Pseudo SRAM User Interface
Tokyo, February 17, 2003 -- Fujitsu Limited, NEC Electronics Corporation and Toshiba Corporation 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, standardize the basic electrical properties, packaging and pin layout, 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. 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 synchronizing 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 initializes the internal state of the device.
Fujitsu is a leading provider of customer-focused IT and communications solutions for the global marketplace. Pace-setting technologies, high-reliability/performance computing and telecommunications platforms, and a worldwide corps of systems and services experts make Fujitsu uniquely positioned to unleash the infinite possibilities of the broadband Internet to help its customers succeed. Headquartered in Tokyo, Fujitsu Limited (TSE:6702) reported consolidated revenues of 5 trillion yen (about US$38 billion) for the fiscal year ended March 31, 2002. For more information, please see: http://www.fujitsu.com/
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 specializes 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 http://www.necel.com./
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 http://www.toshiba.co.jp/index.htm
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