Memory makers are already beginning to sample DDRII, which, according to the JEDEC standard, will have 240 pins and offer electrical performance improvements by implementing signal termination inside of the memory die and offering pre-fetch four instead of pre-fetch two, which is the current standard.
Based on a .10 micron process, DDRII is expected to start at 400 MHz then go to 533 MHz and 667 MHz, which are impossible with DDRAM-1 technology. While the module will be different, the memory core will be the same as for DDRAM1. Application-wise, DDRII will also generate lower voltage for laptops.
A patent filed by Micron includes a description of how a DDRII JEDEC standard module accesses and outputs four bits of data within one read cycle. DDRII effectively accesses and outputs twice the amount of data than DDR.
A group of four bits is accessed at a time, and is output to the data pad in two clock cycles, or two bits in each of the two clock cycles. The four bits processed per clock cycle, however, pose a challenge. Unlike DDR in which four bits are from the same group, DDRII must distinguish which two of the four bits to output in which one of the two clock cycles. Also, a proper bit order must be determined so that each of the four bits is output to the data pad in a correct order.
But while the top-tier memory makers have already begun to sample DDRII, evidence exists that mass production of DDRII will be one year late and will not happen until 2005. According to industry sources, suppliers are looking at DDR400 for market acceptance first. There are also reported design delays of compatible chipsets.
Most memory vendors still maintain that DDRII modules will become commercially available next year.
ATI And Nvidia: A DDRII Vision Of Things To Come?
Do ATI and Nvidia graphics chipsets represent the future of memory technology?
After a long awaited deadline and the first production delay in Nvidia Corp.'s history, Nvidia launched its GeForce FX graphics card and offered the memory world the first consumer application for 1 GHz DDRII. Only days after, ATI anted up with its Radeon 9800 DirectX 9 VPU with DDRII. While the memory and bus speeds of the graphics processor platforms are amazing enough, both devices also portend what will be possible when DDRII and accompanying CPU chipsets come together - hopefully in less than two years. Both the Radeon 9800 and the GeForceFX offer over 100 million transistors, more than twice the size of a Pentium 4 CPU.
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