Emerging memories

In phase-change memory (PCM), how can multiple bits be stored in one cell (multi-level storage)?

  1. ABy changing the color of the cell
  2. BBy using multiple magnetization directions in the cell
  3. CBy controlling, for example, the size of the amorphous region in the cell to create intermediate resistance values
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Answer: C. By controlling, for example, the size of the amorphous region in the cell to create intermediate resistance values

In PCM, controlling the proportion of amorphous and crystalline regions in a cell produces intermediate resistances between high and low. Distinguishing several resistance levels allows multiple bits per cell. However, effects such as resistance drift make stable discrimination between levels a challenge.

  • A. PCM stores data as electrical resistance, not color.
  • B. Storing data as magnetization direction is MRAM.
  • C. Correct. Intermediate resistance values are created.
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More Emerging memories questions

  1. Which memory changes resistance by having metal ions such as silver or copper move through a solid electrolyte to form or break a conductive path?
  2. What is the difference between "bipolar" and "unipolar" operation of ReRAM?
  3. In cross-point memories such as PCM, which chalcogenide device, placed in series with the storage element as a selector, suddenly conducts above a certain voltage?
  4. Why must the read current be limited in STT-MRAM?
  5. Which device uses the fact that the tunneling current through a thin ferroelectric layer depends on the direction of its polarization?