Memory Term & Spec:

  • BBWC and FBWC -
    BBWC is a Battery Backed Write Cache Memory. Raid arrays use a battery backed cache so they
    can process data faster than they can write it. Without the battery, they couldn't do caching without risk of data loss during a power failure. There is DRAM memory module which contents are retained as long as the battery has some juice left.
    FBWC is a flash based cache module that does not have the battery limitation of how long it can retain what is written to the module.
    These modules do not require a battery. They have super capacitors to provide power to flash write cache memory
  • Cache Memory -
    Cache memory, also called CPU memory, is random access memory (RAM) that a computer microprocessor can access more quickly than it can access regular RAM. This memory is typically integrated directly with the CPU chip or placed on a separate chip that has a separate bus interconnect with the CPU. The basic purpose of cache memory is to store program instructions that are frequently re-referenced by software during operation. Fast access to these instructions increases the overall speed of the software program.
  • DDR SDRAM DIMM -
    Double data rate synchronous dynamic random-access memory (DDR SDRAM) is a class of memory integrated circuits used in computers. DDR SDRAM, also called DDR1 SDRAM, has been superseded by DDR2 SDRAM, DDR3 SDRAM and DDR4 SDRAM. None of its successors are forward or backward compatiblewith DDR1 SDRAM, meaning DDR2, DDR3, and DDR4 memory modules will not work in DDR1-equipped motherboards, and vice versa. Compared to single data rate (SDR) SDRAM, the DDR SDRAM interface makes higher transfer rates possible by more strict control of the timing of the electrical data and clock signals.
  • DDR2 SDRAM DIMM -
    Its primary benefit is the ability to operate the external data bus twice as fast as DDR SDRAM. This is achieved by improved bus signal. The prefetch buffer of DDR2 is 4 bit(double of DDR SDRAM). DDR2 memory is at the same internal clock speed (133~200MHz) as DDR,  but the transfer rate of DDR2 can reach 533~800 MT/s with the improved I/O bus signal. DDR2 533 and DDR2 800 memory types are on the market.
  • DDR3 SDRAM DIMM -
    DDR3 memory reduces 40% power consumption compared to current DDR2 modules, allowing for lower operating currents and voltages (1.5 V, compared to DDR2's 1.8 V or DDR's 2.5 V). The transfer rate of DDR3 is 800~1600 MT/s. DDR3's prefetch buffer width is 8 bit, whereas DDR2's is 4 bit, and DDR's is 2 bit. DDR3 also adds two functions, such as ASR (Automatic Self-Refresh) and SRT (Self-Refresh Temperature). They can make the memory control the refresh rate according to the temperature variation
  • DDR4 SDRAM DIMM -
    DDR4 SDRAM provides the lower operating voltage (1.2V) and higher transfer rate. The transfer rate of DDR4 is 2133~3200 MT/s. DDR4 adds four new Bank Groups technology. Each bank group has the feature of singlehanded operation. DDR4 can process 4 data within a clock cycle, so DDR4's efficiency is better than DDR3 obviously. DDR4 also adds some functions, such as DBI (Data Bus Inversion), CRC (Cyclic Redundancy Check) and CA parity. They can enhance DDR4 memory's signal integrity, and improve the stability of data transmission/access.
  • Compare SDRAM, DDR, DDR2, DDR3, DDR4 -
  • ECC -
    Error-correcting code memory (ECC memory) is a type of computer data storage that can detect and correct the most common kinds of internal data corruption. ECC memory is used in most computers where data corruption cannot be tolerated under any circumstances, such as for scientific or financial computing. Most non-ECC memory cannot detect errors although some non-ECC memory with parity support allows detection but not correction.
    ( info source:
    https://en.wikipedia.org/wiki/ECC_memory )
  • RAM -
    Random Access Memory is a type of computer memory that can be accessed randomly and holds data temporarily while the CPU is processes the data. There are two type of RAM categories:
  • DRAM -
    Dynamic Random Access Memory. DRAM has to be refreshed thousands of time per second. DRAM is the most common type of RAM. Both DRAM & SRAM lose their content when power if turned off.
  • SRAM -
    Static Random Access Memory. SRAM does not need to be refreshed and the access time is about 10 nanoseconds. SRAM is more expensive. Both DRAM & SRAM lose their content when power if turned off.
  • SDRAM -
    Synchronous DRAM is a generic name for various kinds of DRAM that are synchronized with the clock speed that the microprocessor is optimized for. This tends to increase the number of instructions that the processor can perform in a given time. As the first RAM to be in sync with the system clock so that it has 2 notches and 168-pin.
  • DIMM -
    Dual Inline Memory Module
  • Fully Buffered DIMM -
    Fully Buffered DIMM (or FB-DIMM) is a memory technology that can be used to increase reliability and density of memory systems. Conventionally, data lines from the memory controller have to be connected to data lines in every DRAM module, i.e. via multidrop buses. As the memory width increases together with the access speed, the signal degrades at the interface between the bus and the device. This limits the speed and memory density, so FB-DIMMs take a different approach to solve the problem. 240-pin DDR2 FB-DIMMs are neither mechanically nor electrically compatible with conventional 240-pin DDR2 DIMMs. As a result, those two DIMM types are notched differently to prevent using the wrong one.
    ( info source: https://en.wikipedia.org/wiki/Fully_Buffered_DIMM, published by JEDEC Solid State Technology Association )
  • RIMM -
  • C-RIMM -
  • SIMM -
    Single Inline Memory Module
  • SIMM-30 -
  • SIMM-72 -
  • FPM -
    Fast Page memory, used with 30-pin or 72-pin or some 168-pin DIMM
  • EDO -
    Extended Data Out, improved on FPM, used with 72-pin SIMM or some 168-pin DIMM
  • BEDO -
    Burst EDO, improved on EDO, is rarely used and can be used with 72-pin SIMM or some 168-pin DIMM
  • Single Sided and Double Sided -
    These are the physical terms describing the arrangement of the chips on one side or two sides of the memory module. On a double sided module the chips are on both sides of the module. Single sided modules are newer with chips that are denser, enabling more capacity. Older motherboards may not recognize single sided modules
  • Size of Memory -
    • mega byte / megabyte / meg / megs - 64mb, 128mb, 256mb, 512mb, 640mb, 768mb, 1024mb (=1gb)
    • giga byte / gtigabyte / gig / gigs - 1gb, 2gb, 3gb, 4gb, 8gm (=8192mb)
  • Standards, Styles, Speed of RAM Modules -
    • DIMM -
      • Long / Short
      • High Profile / Low Profile
      • Inline / Single Sided / Double Sided
      • Branded / Generic
      • Buffered / Unbuffered
      • cl - cas latency
      • 144-pin / 168-pin / 184-pin / 200-pin / 240-pin
      • 533MHz / 667MHz / 800MHz / 1000MHz / 1066MHz
      • PC66 / PC100 / PC133 / PC1600 / PC1800 / PC2100 / PC2700 / PC3200 / PC3500 / PC3500 / PC3700 / PC4000 / PC4200 / PC5300 / PC6400 / PC8000 / PC8500
      • PC2-
      • PC3-

Memory Pictures: