None of its successors are forward or backward compatible with DDR1 SDRAM, meaning DDR2, DDR3, DDR4 and DDR5 memory modules will not work on DDR1-equipped motherboards, and vice versa.

One advantage of keeping the clock frequency low is that it reduces the signal integrity requirements on the circuit board connecting the memory to the controller.

In the late 1980s IBM invented DDR SDRAM, they built a dual-edge clocking RAM and presented their results at the International Solid-State Circuits Convention in 1990.

[6][7] Samsung released the first commercial DDR SDRAM chip (64 Mbit) in June 1998,[3] followed soon after by Hyundai Electronics (now SK Hynix) the same year.

[9] JEDEC has set standards for the data rates of DDR SDRAM, divided into two parts.

Adding modules to the single memory bus creates additional electrical load on its drivers.

To mitigate the resulting bus signaling rate drop and overcome the memory bottleneck, new chipsets employ the multi-channel architecture.

[12] All RAM data rates in-between or above these listed specifications are not standardized by JEDEC – often they are simply manufacturer optimizations using tighter tolerances or overvolted chips.

21–C defines three possible operating voltages for 184 pin DDR, as identified by the key notch position relative to its centreline.

One should definitely be careful buying 1 GB memory modules, because all these variations can be sold under one price position without stating whether they are ×4 or ×8, single- or dual-ranked.

79 Revision Log: "This comprehensive standard defines all required aspects of 64Mb through 1Gb DDR SDRAMs with X4/X8/X16 data interfaces, including features, functionality, ac and dc parametrics, packages and pin assignments.

The individual chips making up a 1 GB memory module are usually organized as 226 8-bit words, commonly expressed as 64M×8.

DDR2 was in turn superseded by DDR3 SDRAM, which offered higher performance for increased bus speeds and new features.

Although the effective clock rates of DDR2 are higher than DDR, the overall performance was not greater in the early implementations, primarily due to the high latencies of the first DDR2 modules.

The 8n prefetch architecture is combined with an interface designed to transfer two data words per clock cycle at the I/O pins.

[20] RDRAM was a particularly expensive alternative to DDR SDRAM, and most manufacturers dropped its support from their chipsets.

Through techniques including reduced voltage supply and advanced refresh options, Mobile DDR can achieve greater power efficiency.