Numonyx has announced or reannounced two 128-Mbit non-volatilve memory devices based on the company’s 90nm PCM (phase change memory) process technology. These two devices target existing NOR Flash memory sockets and the company’s press release claims that both products are available now in production quantities. The two announced PCM memory devices are the Omneo P8P PCM parallel-I/O memory and the Omneo P5Q PCM serial-I/O memory. The Omneo P5Q PCM device is configured as a 16Mx8-bit memory and employs an SPI interface and supports dual and quad SPI protocols. The Omneo P8P PCM device is configured as an 8Mx16-bit memory with a 16-bit parallel I/O interface and the device has a secondary SPI channel for issuing block commands to the device and for low-pin-count, in-system programming.

The initial read access time for the parallel PCM device is given as 115 nsec with 25 nsec for subsequent reads during 8-word (the parallel device is configured as a x16-bit memory) , asynchronous page reads. Write cycle time is a short 70 nsec, but the writes are buffered internally by a 64-byte FIFO that masks the actual cell-specific write time. Using the same memory cell, the serial P5Q PCM memory device’s read-access time is constrained by the SPI interface, not the fundamental access time of the memory cell. One of the big advantages of PCM over NOR Flash is the ability to directly write one memory location with no need for an erase cycle.

Two significant attributes of the devices, made significant because of the technical issues surrounding, are the announced write endurance and the operating temperature range of the devices. Numonyx had previously announced a version of the P8P PCM with 100,000-cycle write endurance. The latest announcement jumps the rated write-cycle endurance for both the P8P and the P5Q memory devices to 1M write cycles.

Operating temperature is important because PCM employs a thermally activated storage mechanism. Ones and zeroes are stored in PCM cells based on a heating/cooling cycle. Fast cooling produces an amorphous state in the PCM’s chalcogenide material and slow cooling essentially anneals the cell into a crystalline state. If the ambient temperature is too high, the heat alone will start to anneal PCM cells. Numonyx’ data sheets give both memories’ operating temperature range as 0 to 70° C.

With data sheets on line and announced volume availability, these two PCM devices from Numonyx appear to the first commercially available, commercially viable PCM devices on the market. Numonyx is not currently disclosing pricing except to say they’re currently charging a premium given that the devices are not very far down the learning curve. However, given the activity that the company has put into presentations and articles over the past two years, they likely are not the last.