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DDR SDRAM, also retroactively called DDR1 SDRAM, has been superseded by DDR2 SDRAM, DDR3 SDRAM, DDR4 SDRAM and DDR5 SDRAM. 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.
As a result, DDR SDRAM is not backwards compatible with SDR SDRAM. DDR SDRAM (sometimes called DDR1 for greater clarity) doubles the minimum read or write unit; every access refers to at least two consecutive words. Typical DDR SDRAM clock rates are 133, 166 and 200 MHz (7.5, 6, and 5 ns/cycle), generally described as DDR-266, DDR-333 and DDR ...
The first commercial SDRAM chip was the Samsung KM48SL2000, which had a capacity of 16 Mb, [26] and was introduced in 1992. [27] The first commercial DDR SDRAM (double data rate SDRAM) memory chip was Samsung's 64 Mb DDR SDRAM chip, released in 1998. [28] Later, in 2001, Japanese DRAM makers accused Korean DRAM manufacturers of dumping. [29 ...
For example, DDR SDRAM has a refresh time of 64 ms and 8,192 rows, so the refresh cycle interval is 7.8 μs. [5] [9] Generations of DRAM chips developed after 2012 contain an integral refresh counter, and the memory control circuitry can either use this counter or provide a row address from an external counter.
Double Data Rate 3 Synchronous Dynamic Random-Access Memory (DDR3 SDRAM) is a type of synchronous dynamic random-access memory (SDRAM) with a high bandwidth ("double data rate") interface, and has been in use since 2007. It is the higher-speed successor to DDR and DDR2 and predecessor to DDR4 synchronous dynamic random-access memory (SDRAM) chips.
[a] Physical comparison of DDR, DDR2, DDR3, and DDR4 SDRAM Front and back of 8 GB [1] DDR4 memory modules. 2005: Standards body JEDEC began working on a successor to DDR3 around 2005, [14] about 2 years before the launch of DDR3 in 2007. [15] [16] The high-level architecture of DDR4 was planned for completion in 2008. [17]
DDR2 DIMMs are not backward compatible with DDR DIMMs. The notch on DDR2 DIMMs is in a different position from DDR DIMMs, and the pin density is higher than DDR DIMMs in desktops. DDR2 is a 240-pin module, DDR is a 184-pin module.
In a typical synchronous dynamic random-access memory (SDRAM) or double data rate SDRAM (DDR SDRAM), a bank consists of multiple rows and columns of storage units, and is usually spread out across several chips. In a single read or write operation, only one bank is accessed, therefore the number of bits in a column or a row, per bank and per ...