Phase Change Memory PCM

1
Phase Change Memory (PCM)?

• 640K of memory should be enough for anybody.''
• -- Bill Gates

2
Volatile Memory

• Random Access Memory
• Static RAM SDRAM
• Dynamic RAM DRAM
• Content-addressable memory
• Cache Controller

3
Non-Volatile Memory

• Read Only Memory
• Flash Memory
• Magnetic Storage
• Hard Disks
• Floppy Disks
• Magnetic Tape
• Optical Storage
• Dead tree (punch cards)?

• And....

4
Phase Change Memory

• PRAM uses the unique behavior of chalcogenide
  glass, which can be "switched" between two
  states, crystalline and amorphous, with the
  application of heat. Recent versions can achieve
  two additional distinct states, effectively
  doubling its storage capacity.
• --Wikiepedia
• link

5
History

• Originaly reearched in the 1960's Gordon Moore of
  Intel wrote a research paper about the benefits
  and memory implications of chalcogenide glasses

6
Physical Properties

• Diferent states have different qualities
• Amorphorous State
• High resistivity represents 0
• Crystaline State
• Low resistivity represents
• Different states have different optical
  properties
• Used in re writable cds/dvds

7
Flash vs Pram

• Flash
• Changeing Bits must be across blocks
• Requires a time to build up a charge (1 ms)?
• Degrades with use (10,000 to 100,000 writes)?
• Pram
• Individual bits can be changed
• Low power consumption
• Degrades slowly (100 million)?
• At 85 C data can last 300 years

8
PRAM today

• 2004 Samsung Prototyped a 512 MB module
• 2006 Intel created a mass producible 128 module
• 2008 Inte discovered 2 addition states
  effectively doubling the Capacity
• 2008 Intel begins shipping beta version called
  Alverstone

9
Phase Change Memory (PCM)?

• Grant Callaghan
• Sources
• Wikipedia
• Murdocca,Miles Computer Architecture and
  Organization , 2007 John Wiley and Sons
• San Jose State Professor Sin Min Lees cs147 slides