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3D XPoint

(3D Cross Point) A non-volatile phase change memory and storage technology from Intel and Micron. Optane is Intel's brand for 3D XPoint, while Micron uses the QuantX moniker. Less expensive and denser than dynamic RAM (DRAM), XPoint is more costly than NAND flash but is considerably faster while using less power.

Memory and Storage
3D XPoint has unique attributes. Like all RAM chips (DRAM and SRAM), 3D XPoint is byte addressable and can thus be used as main memory or as a secondary RAM bank. Because it is non-volatile, it can also replace an SSD or hard drive or be used in conjunction with them. A stackable architecture, XPoint is up to 10 times denser than DRAM. See byte addressable.

Cross Point Structure
Voltage applied to the top and bottom wire of the selector causes the cell to be read or written, and transistors are not required at each cell like they are with DRAM. Unlike flash memory that has a limited life span, XPoint is not affected by the number of write cycles. (Image courtesy of Intel.)

         Byte        Non-
      Addressable  Volatile   Speed

 SRAM     Yes        No      Fastest

 DRAM     Yes        No      Faster

 XPoint   Yes        Yes     Fast

 NAND     No         Yes     Slow

byte addressable

A primary characteristic of random access memory (RAM), which comprises the common DRAM and SRAM chips in every computer. Highlighting the essential difference between memory and storage, byte addressability means that a single character can be read from or written to any memory byte, whereas disks, SSDs and flash drives are read and written in fixed chunks of hundreds or thousands of bytes. Byte addressability enables even a single numeric digit to be calculated, compared and copied independently of the data residing in the bytes next to it. Contrast with block addressable. See storage vs. memory, 3D XPoint, memory, solid state drive and magnetic disk.

Each Byte Is Addressable
Byte addressable RAM allows contiguous data to be split apart for human readability. For more examples, see computer.

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