As the world adapts to flash storage, the medium’s limitations are now becoming more apparent. Researchers are looking for faster storage media because the only other faster storage media we have, RAM, is too expensive and impermanent.
What is Phase Change Memory?
The folks at IBM have arrived at a breakthrough for phase change memory (PCM) which has the potential to one day replace RAM and flash storage. This storage type, which is crystal based, was used in optical disks and different technologies since the past 15 years or so but it was limited by storage density and costs incurred in producing it. The cells used in PCM are “on” or “off” but the researchers at IBM have discovered a way to store 3 bits of data per cell, drastically improving the capacity of the original technology.
How It Works
The way they do it is this. When PCM data is stored on a Blu-ray disk, a high current is applied on the non-crystal material, making them more conductive. The data is then read by applying a lower voltage to read the high “1” and low “0” states. To store more states, the material can be heated but the crystals move, depending on the temperature. The IBM researchers have found out a way to use those variations to store 3 bits of data instead of just “1” and “0”.
This makes PCM a viable candidate for future use as storage media, it’s faster than flash storage but costs about the same as RAM does currently because of lower density. Dr. Haris Pozidis says that:
Reaching 3 bits per cell is a significant milestone because at this density the cost of PCM will be significantly less than DRAM and closer to flash.
Phase change memory is used for optical disks currently but with this discovery it is now feasible to use in more media. It could be used with flash memory in cell phones to make a faster cache, leading to faster boot times and app launches for the phones.
Another potential application for this type of memory could be in time critical scenarios. The data read time is less than 1 microsecond which is 70 times less than conventional flash memory. RAM is faster but PCM could replace both flash and RAM and be used as the primary storage medium.
This technology needs to be developed commercially and also needs to go head to head against memristors and resistive RAM. The people at IBM think that it’s just the right type of storage media for artificial intelligence application like IBM’s own “Watson”.