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(Synchronous DRAM) The type of dynamic RAM memory chip that has been widely used since the mid-1990s. SDRAM eliminated wait states by dividing the chip into two cell blocks and interleaving data between them. While a bit in one block is accessed, a bit in the other is prepared for access. See dynamic RAM.

DDR (Double Data Rate)
In 2000, DDR SDRAM doubled the data transfer rate by using both the rising and falling edges of the clock cycle. The data rate of each DDR generation is faster than the previous with a six-fold increase from DDR1 to DDR4. In addition, less power is required (see table below). In order to prevent inserting the wrong DDR into the motherboard, DDR memory modules are keyed differently (for details, see memory module).

Chipsets on the motherboard may support one, two or four memory channels (triple channel has since come and gone). For example, mainstream motherboards support dual channel, which is why memory modules are generally installed in pairs. While data are being read or written to one memory module, the second module is being prepared for reading or writing. High-end motherboards support quad channel. See SGRAM.


  Following are the most popular memory
  module speeds for each SDRAM generation.

       Memory Speed   DIMM   Voltage          (MHz)      Module  Required

  DDR4     2400     284-pin   1.2
  DDR4     2133     284-pin   1.2

  DDR3     1866     240-pin   1.35/1.5
  DDR3     1600     240-pin   1.35/1.5
  DDR3     1333     240-pin   1.35/1.5

  DDR2      800     240-pin   1.8/2.5

  DDR       400     184-pin   2.5

  SDRAM     133     168-pin   3.3
  SDRAM     100     168-pin   3.3

Matched Slots for Dual Channel
This motherboard uses colored sockets so that module pairs are inserted properly. It supports three pairs (one orange and two lavender). (Image courtesy of Giga-byte Technology Company Ltd.,

A Little Nostalgia
These 12 bits of magnetic core memory from the Whirlwind computer of the early 1950s take up about a quarter of a square inch. Today, that much space holds hundreds of millions of bits. (Image courtesy of The MITRE Corporation Archives.)
References in periodicals archive ?
SDR SDRAM memories use a synchronous interface with all inputs referenced to the rising edge of an incoming clock.
The Court ordered Hynix to pay Rambus royalties on net sales after January 31, 2009 and before April 18, 2010 of 1% for SDR SDRAM and 4.
The Court also ordered Hynix to pay Rambus royalties on net sales after January 31, 2009 and before April 18, 2010 of 1% for SDR SDRAM and 4.
According to the order, Hynix is to pay Rambus royalties of 1% for SDR SDRAM products and 4.
Northwest Logic specializes in PCI Cores including PCI Express, PCI-X and PCI and Memory Controller Cores including DDR2, DDR and SDR SDRAM.
1) MIPS at 166MHz -- eMAC module and hardware divide -- Eight KB I/D-cache,16KB SRAM -- Optional 10/100 Ethernet media access controller -- Three UARTs -- QSPI -- Inter-IC bus interface -- Four 32-bit timers with DMA support -- 16-channel DMA controller -- 16-bit DDR / 32-bit SDR SDRAM controller -- Up to 50 general-purpose I/O -- System integration: phased-lock loop (PLL), software watchdog -- 1.
MemConnect supports a full range of memory devices, including: SDR SDRAM, DDR, DDR2, Mobile SDRAM, FCRAM, Flash, Synchronous Flash, SRAM, EEPROM, and NAND Flash.
Southbridge: ALI 1535+ BIOS Phoenix BIOS, supports ACPI, DMI, PnP System Memory 1 x DDR socket for DDR SODIMM modules (supplied with 128MB DDR-266) 1 x DIMM socket for SDR SDRAM modules I/O Features 1 x Floppy Disk (up to 2.
This latest surge in DDR and SDR SDRAM consumption at Hynix has been driven by a number of factors occurring in the industry.
The Altera memory controller portfolio also includes a DDR SDRAM controller MegaCore function and will add an SDR SDRAM controller MegaCore function in December.