1.0 Hardware

1.6 Compare and contrast memory types, characteristics and their purpose

• Types
  • DRAM
    • Dynamic Random Access Memory
    • Needs refreshing

  
  
  • SRAM
    • Static Random Access Memory
    • Frequently used in processors
    • Does not need refreshing
    • More expensive and faster than DRAM

  
  
  • SDRAM
    • Synchronized Dynamic Random Access Memory
    • Runs on clock speeds
    • 3.3 volts
    • 168 pins

  
  
  • DDR

    Double data rate is a type of SDRAM in which data is sent on both the rise and fall of the clock cycle.

    • Twice as fast as SDRAM
    • Also refered to as "Double Pumping"
    • 2.5 volts
    • 184 pins

  
  
  • DDR2
    • Twice as fast as DDR
    • 240 pin DIMM

  
  
  • DDR3
    • Four times as fast as DDR
    • 240 pin DIMM

  
  
  • RAMBUS
    • Designed by Rambus, Inc.
    • Modules known as RIMM (Rambus Inline Memory Module)
    • Current use is limited
    • Equipped with heat shields
    • Runs at a multiplier of clock speed
    • Reads data on both rise and fall of clock cycle
    • 184 pins
    • Installed in pairs
    • Requires a module called CRIMM for open slots

  
  


• Parity vs. Non-parity
  • Parity
    • Uses an additional chip for parity
    • Higher cost due to additional chips
    • Cannot correct, but can detect errors

  
  
  • Non-parity
    • Has fewer chips
    • Does not need to calculate parity
    • Non-parity systems have no fault tolerance

  
  
• ECC vs. non-ECC
  What's the Difference? (Video by CrucialMemory)
  
  
  • ECC
    • Error Correcting Code
    • Capable of detecting and correcting errors
    • Used in high-end systems
    • Motherboard must support ECC

  
  
  • Non-ECC
    • Is not capable of correcting errors

  
  
• Single sided vs. double sided
  Refers to memory ranks or groupings
  Not a reference to the physical sides of memory modules
  
  
  • Single sided

    Refers to a single rank of chips in which the computer can access all at once.

  
  
  • Double sided
    • A type of memory in which its chips are divided into two ranks
    • Only one rank can be accessed at a time
    • Access must switch from one rank to the other and back again

  
  
• Single channel vs. dual channel
  
  
  • Single channel
    
    • Memory controller can only access one module at a time

  
  
  • Dual channel
    
    • Requires a motherboard capable of dual-channel technology
    • Requires two or more memory modules
    • Best to use identical pairs of memory modules
    • Memory banks are typically color-coded

  
  
• Speed
  • PC100
    
    • 100 MHz clock speed
    • 168-pin DIMM form factor
    • 144-pin SO-DIMM for laptops
    • 3.3 volts

  
  
  • PC133
    
    • 133 MHz clock speed
    • 168-pin DIMM form factor
    • 168-pin SO-DIMM for laptops
    • 3.3 volts

  
  
  • PC2700
    
    • DDR-333
    • 166 MHz clock speed
    • 184-pin DIMM form factor
    • 200-pin SO DIMMS or 172-pin micro-DIMMS for laptops
    • 3.3 volts

  
  
  • PC3200
    
    • DDR-400
    • 200 MHz clock speed
    • 184-pin DIMM form factor
    • 200-pin SO DIMMS or 172-pin micro-DIMMS for laptops

  
  
  • DDR3-1600
    
    • PC3-12800
    • 200 MHz clock speed
    • 240-pin DIMM form factor
    • 204-pin SO DIMM for laptops
    • 1.5 volts

  
  
  • DDR2-667
    
    • PC2-5300
    • 133 MHz clock speed
    • 240-pin DIMM form factor

  
  
  
  

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Professor Messer's
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An Overview of Memory

Identifying Memory Types

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