Fujitsu, NEC, Toshiba agree common spec for pseudostatic RAM

Fujitsu, NEC, Toshiba agree common spec for pseudostatic RAM
TOKYO -- In a bid to reinforce their market position in pseudostatic RAM (PSRAM) devices, Fujitsu Ltd., NEC Corp. and Toshiba Corp. have extended collaboration on interface specifications to include a burst-mode PSRAM and the stacked multi-chip packages (MCPs) that house the devices.

The PSRAM uses a DRAM memory cell to achieve high density and low bit cost, but has an asynchronous SRAM external interface. Demand for these devices is increasing as "working memory" for performance-rich mobile phones such as Japanese i-mode and 3G phones.

The three companies have given the name of COSMORAM (Common Specifications for Mobile RAM) to the common specifications that cover both page-mode and burst-mode PSRAM parts. The burst-mode PSRAM reads out a given length of data bits with synchronized clock input enabling faster memory-access.

The common specifications for burst-mode PSRAM, cover such things as supply voltage range, control pin names, partial refresh function, burst length and corresponding addressing, power-on sequence, pin-outs and packaging.

The timing of the supply of burst-mode parts compliant with the COSMORAM specifications differs at the manufacturers. Fujitsu is expected to have devices in the first half of this year; NEC by the of the year.

As to page-mode parts, Fujitsu began volume production of 32-Mbit parts with the common interfaces in January this year and NEC plans to introduce devices in the first half of the year.