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Memory DRAM, SRAM, SDRAM

RAM(Random Access Memory)

ram.png

Geeks for Geeks Deepanshi_Mittal

SRAM(Static Random Access Memory)

  • complicated circuit
  • high speed
  • expensive
  • cache

    Memory Cell

    SRAM.png

    Geeks for Geeks SAYAN KUMAR PAL

    stores data by current flow using flip-flop circuit

    if power is supplied and current is always flowing, stored data can be kept.

  • Read operation

    the word line is activated by the address input

    -> closes both the transistors T1 and T2

    -> the bit values at points A and B are transmit to their bit lines

    -> the sense/write circuit sent the output to the processor

  • Write Operation

    the address activates the word line to close both the switches

    -> the bit value is provided

    -> signals in bit lines are stored in the cell

DRAM(Dynamic Random Access Memory)

  • simple circuit
  • high memory density
  • large power consumption
  • main memory

    Memory Cell

    DRAM.png

    Geeks for Geeks SAYAN KUMAR PAL

  • required an operation to replenish the charge called "refresh"

    one transistor(T) and one capacitor(C) in each cell

    stores data by a capacitor, but charge gradually escapes as time passes

SDRAM(Synchronous Dynamic Random Access Memory)

DRAM operating in synchronization with clock signal

After late 1990~ prevailed as standard RAM

enabled pipelining

latency: Delay from read command to data output

SDR_SDRAM-1.jpg

"Eight Hyundai SDRAM ICs on a PC100 DIMM package." Wikipedia Synchronous dynamic random-access memory

typical clock speeds(bandwidth): 66Mhz, 100Mhz and 133MHz(15ns, 10ns, 7.5ns)

Generally modularized in the form of 168-pin DIMMs(Dual Inline Memory Module), it can read and write 64 bits (no ECC) or 72 bits (ECC) at one time.

Summary

difference-1.png

Geeks for Geeks Deepanshi_Mittal

References

Wikipedia Dynamic random-access memory. https://en.wikipedia.org/wiki/Dynamic_random-access_memory

Wikipedia Static random-access memory. https://en.wikipedia.org/wiki/Static_random-access_memory

Wikipedia Synchronous dynamic random-access memory. https://en.wikipedia.org/wiki/Synchronous_dynamic_random-access_memory

Geeks for Geeks Deepanshi_Mittal, Types of computer memory (RAM and ROM). https://www.geeksforgeeks.org/types-computer-memory-ram-rom/

Geeks for Geeks SAYAN KUMAR PAL, Different Types of RAM (Random Access Memory). https://www.geeksforgeeks.org/different-types-ram-random-access-memory/


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Last-modified: 2019-07-18 (木) 09:37:39 (792d)