Today's only popular non volatile memory is flash memory. Though the market is growing very well for this non-volatile early bird, it has got it's own set of problems in replacing either Hard-disk or DRAMs completely. The long access time of milli seconds and limited life span of less than 100,000 write cycles are the main complaints of this memory.
Many leading semiconductor companies (Intel, Samsung, IBM, Freescale, TI, RAMTRON, and many more) are developing alternative technologies to flash and get rid of the entire drawback the flash has. Here in this article, we briefly touch upon the technology and give some basic idea of each NVRAM concepts.
Here we go by the order of their commercialization.
FRAM (Ferro Random Access Memory): Ramtron has pioneered in commercializing this technology. FRAM is already available in huge production quantities. You can also source 8051 based microcontroller's integrated with FRAM. The speed and life is very good compared to Flash. However the maximum capacity available is uncomparable to flash.You hardly get 1MB in a chip.
The technology is based on DRAM itself. In DRAM the capacitor stores the charge but need to be refreshed due to capacitor's leakage, say you replace the capacitor with a ferro-electric material called Lead Zirconate Titanate (PZT) so that the charge stays there even without power, than it is FRAM.
In the present scenario there are few applications where FRAM can perform far better than Flash. The long term future of FRAM can be positive if the size increases and cost per MB falls.
MRAM (Magnetoresistive Random Access Memory): Freescale is the company which is sitting pretty well on this technology and also launched 4M bit chip in 2006. It is yet to know how market is responding to this new chip. If the technology is compared to DRAM and flash, all the key factors shows, this can become future NVRAM. It all depends on how fast the cost per MB falls close to flash and sizes of giga-byte are released at the earliest.
This technology is also similar to DRAM. The key storage element is a set of two magnetic plates. One plate is permanent magnet and other is magnetically charged to high or low.
It's as fast as SRAM and also can scale down to store huge capacities and read/write cycles written can be infinite.
PRAM (Phase change Random Access Memory): Samsung has demonstrated prototype of 256 MB PRAM in Sept 06. Along with the benefits of what MRAM offers over flash, PRAM also has size advantage. We can expect the working model of 512MB capacity from Samsung after once it's commercialized.
The problem with PRAM is, the technology is still in experimental stage. We can only confirm it's lead over flash and other NVRAMs only when the production volumes are announced. However it can be suggested to seriously watch this technology for potential replacement of flash.
Other NVRAM technologies: The world is waiting for nano technology to produce MOSFETS and other storage devices at nano scales. There are many papers getting published and serious research is going on in every hi-tech institutes around world on nano technology. One name popping up is Nano RAM; made using nanotubes. Once we see new memory or processor devices from nano-technology all the present technologies will be dropped like how old vaccum tube technology is dropped. Nothing can be predicted on this at this stage except there will be some pleasant shock in near future.