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Hardware Science

Computer Memory Can Be Read With a Flash of Light 69

Posted by Soulskill
from the whose-bright-idea-was-this dept.
ananyo writes "A new kind of computer memory can be read 10,000 times faster than flash memory using pulses of light, taking advantage of principles used in solar panel design. Researchers built the prototype device using bismuth ferrite. In conventional computer memory, information is stored in cells that hold different amounts of electric charge, each representing a binary '1' or '0.' Bismuth ferrite, by contrast, and can represent those binary digits, or bits, as one of two polarization states, and, because of its photovoltaic properties, can switch between these states in response to visible light."
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Computer Memory Can Be Read With a Flash of Light

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  • by TechyImmigrant (175943) on Wednesday June 12, 2013 @02:10PM (#43987609) Journal

    No. SRAM and DRAM are not particularly faster than flash for read operations. The bigger impact on flash vs. SRAM is that SRAM is often on chip whereas flash is stuck behind a slow interface.

    Flash is many times slower for erase and write operations.

  • Comparison to PCM (Score:5, Informative)

    by enriquevagu (1026480) on Wednesday June 12, 2013 @02:30PM (#43987891)

    The link to the actual Nature Communications paper is here: Non-volatile memory based on the ferroelectric photovoltaic effect [nature.com].

    This somehow resembles Phase-Change Memory [wikipedia.org] (PCM). PCM devices are composed of a material which, under a high current, there is a thermal fusion and changes to a different material status, from amorphous to crystalline. This changes two properties: light reflectivity (exploited in CDs and DVDs) and electrical resistance (exploited in emerging non-volatile PCM memories). The paper cites PCM and other types of emerging non-volating memories.

    In this case, it is the polarization what changes, without requiring a thermal fusion, therefore increasing the endurance of the device, one of the main shortcomings of PCM. The other main shortcoming of PCM is write speed due to the slow thermal process, in the paper they claim something like 10ns. If this can be manufactured with a large scale of integration and low cost, it will probably be a revolution in computer architecture.

  • by devjoe (88696) on Wednesday June 12, 2013 @02:40PM (#43988009)
    Actually, this is an error in the summary. The article says that it doesn't change state in response to light, but with an applied voltage. It's read with light that doesn't change the polarization state.
  • by julesh (229690) on Wednesday June 12, 2013 @02:51PM (#43988143)

    No. SRAM and DRAM are not particularly faster than flash for read operations.

    A typical flash chip has a read latency of around 50us (MLC) or 25us (SLC) and can operate one transfer per cycle at about 50-100MHz. A typical DRAM chip has a read latency of around 15ns and can operate two transfers per cycle at about 266-333MHz. A typical SRAM chip has a latency of about 10ns and can operate two transfers per cycle at similar rates to the DRAM.

    Depending on the measure you use, Flash is between 7 and 3,000 times slower at reading than DRAM, and up to 5,000 times slower than SRAM.

  • by BitZtream (692029) on Wednesday June 12, 2013 @03:07PM (#43988317)

    ...

    Uhm, Flash is orders of magnitude slower than DRAM, which is orders of magnitude slower then SRAM.

    SRAM is on chip because its expensive and its interface is expensive so you'd waste a lot of money and effort to have a SRAM discreet component on the other side of the mobo. Designing an interconnect to put the L1/L2 cache in an external chip is a REAL PITA by itself for consumer devices.

    Looks like modern SLC NAND goes at roughly 100ns access times.

    DDR3 - 2000 has a 9ns access time.

    That DDR3 is roughly on par with the SRAM cache on my old 486, which was about 10ns. I have no clue what the internal L1 latency is on something like an i7, but considering that the MHZ is a couple orders a few orders of magnitude higher, I can assume its off the scale faster in comparison to NAND.

    NAND is fast compared to a slow spinning platter disk that has to move a head and a platter into the right position to even get started. Its not really fast otherwise unless you do massively parallel reads. NAND has to do parallel (multiple chips) reads just to keep up with current SATA speeds. The interface isn't the issue.

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