Slashdot Mirror
Samsung To Ship Chip Package With Phase-Change Memory
angry tapir writes "Samsung Electronics will ship a multichip package later this quarter for smartphones that will include phase-change memory (PCM), an emerging technology that could ultimately replace memory types like NOR flash. Samsung's announcement is significant because it marks the first PCM product to be available as part of a multichip package. PCM uses a glass-like material that can change from multiple states to crystalline forms as its atoms are rearranged."
Read Speed
Like RAM and NOR-type flash, the technology features fast random access times. This enables the execution of code directly from the memory, without an intermediate copy to RAM. The read latency of PCM is comparable to single bit per cell NOR flash, while the read bandwidth can match DRAM. In contrast, NAND flash suffers from long random access times on the order of 10s of microseconds that prevent direct code execution.
Write/erase speed
PCM is capable of achieving write speeds like NAND, but with lower latency and with no separate erase step required. NOR flash features moderate write speeds but long erase times. As with RAM, no separate erase step is required with PCM, but the write speed (bandwidth and latency) does not match the capability of RAM today. The capability of PCM is expected, however, however, to improve with each process generation as the PCM cell area decreases.
Orwell: "In a Time of Universal Deceit, telling the Truth is a Revolutionary Act"
[QUOTE]But unlike NOR, PCM consumes more energy as it requires more write cycles, for which it requires more electric currents, Wong said.[/QUOTE]
I'm a new poster, so sorry I don't know how to quote.
Does the quoted bit mean that there is an upper limit on how fast you can write to the chip? Or is the total electrical current pulled for max protocol speed lower than the failure point of the chips? Will this generate excess heat? I'd imagine small chips would heat up fast too, since the writes would be more concentrated (lower memory bits to bits able to be written per second ratio.
If PCM is faster but more expensive than traditional flash, it sounds like it might be useful to incorporate into SSDs as a cache, or alternatively as a separate partition to use as swap or to store the filesystem journal. Is there some reason why this wouldn't work (besides relative unavailability an expense at present)? Is PCM better able to deal with many erasure cycles (which is why SSDs aren't recommended for swap)?
ok - it is going to have the same seek time as a CF card but the read speed of your normal RAM - the write speed will be faster than your CF but slower than your normal RAM
as for Battery life - zero fucking clue
'...if only "Jumping to a Conclusion" was an event in the Olympics.'
Phase change memory has some advantages, but for now and the foreseeable future it can't beat NAND in terms of cell size and price. NAND flash isn't going anywhere anytime soon. NOR, on the other hand, might get phased out in favor of this tech.
Bobb9000 - raised by the wolves,
Oxford education as phrased by the wolves.
yes, but NAND is sloooow compared to NOR for reads. NOR memory (and PCM) looks like a SRAM to your system, thus you can execute directly out of it. NAND is awkward in its structure, so you can not execute directly out of it, instead you must copy the contents of the flash device to RAM.
Practical implications? If your device uses NOR or PCM you can use less DRAM in your design, if you use NAND then you need to increase the amount of RAM, often by as much as the size of the NAND memory (for smaller designs, larger ones will page memory from NAND)
whois gawk date unzip strip find touch finger mount join nice man top fsck grep eject more yes exit umount sleep dump