DRAM Presentation

1
DRAM Presentation

• By Gregory Wilson

2
Getting Started

• History of DRAM
• What is DRAM
• Different types of DRAM
• Conclusion
• Sources

3
History of DRAM

• Invented in 1966 by Robert Dennard at IBM.
• Was the first form of volatile memory for
  computers.
• Helped to set the pace for all present-day
  computers using volatile memory.

4
What is DRAM

• A form of volatile, temporary, memory, like RAM.
• DRAM uses one transistor, while RAM uses six.
• Because of capacitor data leakage, DRAM needs to
  periodically refresh the data it stores.

5
Different Types of DRAM

• There are several different types of DRAM
• Asynchronous DRAM
• Synchronous DRAM
• Video DRAM
• Burst EDO DRAM

6
Asynchronous DRAM

• Most basic form of DRAM.
• Has power connections, a few address inputs, and
  bidirectional data lines.
• Commands from 4 active low control signals.

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Asynchronous DRAMControl Signals

• /RAS (Row Address Strobe) address inputs
  captured at the falling edge of this strobe.
• /CAS (Column Address Strobe) address inputs
  captured at the falling edge of this strobe and
  selects a row from an open row to read/write.
• /WE (Write Enable) determines if a falling edge
  of /CAS is a read (high) or a write (low).
• /OE (Output Enable) controls output to data I/O
  pins.

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Video DRAM (VDRAM)

• Dual-port version of DRAM
• First port accessed as regular DRAM.
• Second sends streams of data to be displayed on
  monitor.
• Almost made obsolete with the intro of SDRAM
  (Synchronous Dynamic Random Access Memory).

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Synchronous DRAM (SDRAM)

• Uses a clock signal before responding to control
  input.
• It is able to synchronize with computers
  processor.
• Clock used to drive internal finite state machine
  for instructions.
• Its chip design has more complex patterns that
  DRAMs

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Synchronous Graphics Random Access Memory (SGRAM)

• Popular in the 1990s and 2000s.
• Specialized form of SDRAM for graphic adaptors.
• Uses a single port.
• Can use bit masking and block writing functions.
• Opens 2 memory pages _at_ one time.

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Work Cited

• Dynamic Random Access Memory. Wikipedia, The
  Free Encyclopedia. 26 April 2007.
• lthttp//en.wikipedia.org/wiki/Dynamic_random_acces
  s_memorygt
• Lemelson-MIT Program. Random Access Memory.
  Inventor of the Week Archive. March 2000. 26
  April 2007.
• http//web.mit.edu/invent/iow/Dennard.html
• SDRAM. Wikipedia, The Free Encyclopedia. 27
  April 2007.
• lt http//en.wikipedia.org/wiki/SDR_SDRAMgt