Ovonic unified memory full report

[seminar class]

SUBMITTED BY
D.SRAVANI

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What is Memory?
CLASSIFICATIONS OF MEMORY:
• Internal Processor Memory
• Main Memory
• Secondary Storage Memory
Memory Device Characteristics:
 Cost
 Access Time and Access Rate
 Access Mode- Random and Serial
 Alterability- ROMS
 Permanence of Storage:
1) Destructive Read-Out
2) Dynamic Volatility
3) Volatility
 Cycle Time and Data Transfer
Limitations of Present Memory Technologies:
 Random Access Memory:
Volatile and expensive.
 Dynamic RAM:
Volatile and difficult to integrate.
 Static RAM:
Expensive.
 Erasable-Programmable Read Only Memory:
High Power Requirement, Poor Flexibility.
 FLASH:
Limited number of Read and Write cycles
Challenges :
• The ability to retain stored charge for long periods with zero applied or refreshed power.
• High speed of data writes.
• Low power consumption.
• Large number of write cycles
Emerging Memory Technologies:
Supports expansion in 3-dimensional spaces
 Fe-RAM:
Data is stored by applying a very low voltage.
 Polymer Memory:
Different conductivity states represents bits of information.
 NROM:
Stacks are used to store charges which writes into memory.
 MRAM:
Data is stored by applying magnetic fields.
 OUM
Ovonic Unified Memory:
 The OUM is non-volatile memory that uses the reversible structural phase-change in thin-film material (e.g., chalcogenides) as the data storage mechanism.
 Electrical energy (heat) is used to convert the material between crystalline (conductive) and amorphous (resistive) phases and the resistive property of these phases is used to represent 0s and 1s.
 Once programmed, the memory state of the cell is determined by reading its resistance.