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Rambus RDRAM

Direct Rambus DRAM was once the preferred memory standard for Intel Corp., the world’s leading producer of microprocessors, and it provided massive bandwidth years before industry-standard dynamic access memory (DRAM) technologies, moreover, RDRAM was considerably more power efficient than its rivals. But now the only place for RDRAM is inside PlayStation 2 and some other proprietary devices, whereas its successor XDR has virtually one design win: PlayStation 3, the worst-selling new-gen video game system. Licensing fees and high manufacturing costs played a bad joke with RDRAM and Rambus itself.

RDRAM memory from Rambus was indeed very advanced for its time. But apart from technological advantages that Rambus could offer to Intel in exchange of support the new memory type by its core-logic sets, Rambus also proposed Intel one million shares for $10 per share in exchange for making  RDRAM a primary industry standard memory. There are smart people working at Intel and they understood pretty well the potential of RMBS stock after RDRAM is announced to become the next memory standard. As a result, the agreement was signed between Intel and Rambus in 1996 and by 2003 RDRAM memory was supposed to become a primary memory standard. One thing Intel and Rambus have forgotten to do is to persuade all manufacturers of DRAM that RDRAM, for which they needed to pay royalties, is the memory of the future.

Nevertheless, in order to popularize RDRAM, in 1998, Intel made a $500 million equity investment in Micron Technology and then paid $100 million to Samsung Electronics in 1999. Still, there were massive amount of Southeast Asia-based memory makers who did not receive incentives from Intel and were rather negative about the prospect to pay royalties to a technology company.

From technology standpoint, RDRAM could bring a lot of benefits for Intel Pentium 4 processors and Netburst micro-architecture. In fact, the giant microprocessor maker needed RDRAM to show off benefits of memory bandwidth hungry Intel Pentium 4 processor and Netburst micro-architecture. But Intel started to popularize RDRAM with the launch of Intel 820 and 840 core-logic sets for Intel Pentium III generation in late 1999.

RDRAM was considerably more expensive compared to SDR SDRAM back then and it was obvious that a lot of customers will not just transit to Rambus memory. As a result, Intel introduced Intel 820 with memory translator hub (MTH) that allowed SDR SDRAM support by the platform. Unfortunately for Intel, MTH did not work correctly which dramatically decreased popularity of the platform, AMD released its successful Athlon processor and Intel had to quickly encourage system makers and end-users to buy platforms based on chipsets from Via Technologies. To make the matters worse, RDRAM did not provide any benefits for Intel Pentium III and it turned out that previous-generation Intel 440BX platform with SDRAM offered higher performance compared to Intel 820 with RDRAM thanks to considerably lower latencies of SDR SDRAM compared to RDRAM: 7.5ns vs. 45ns. Despite of very intensive promotion by the world’s largest chipmaker, Rambus memory faced fiasco in 1999 – 2000 and all the hopes were for the Pentium 4 processor code-named Willamette due in 2000.

The first Intel Pentium 4 processor was released in 2000 not only because Intel needed to push RDRAM into the market place, but also because it continued to face tough competition from AMD: code-named Thunderbird processor from the latter outperformed the Pentium III and the launch of a next-generation processor was meant to return Intel the lead.

Unfortunately for Intel, by late 2000 RDRAM was still expensive and Intel had to bundle two RIMM modules with some of its Pentium 4 chips to ensure the Intel 850-based platform was cost-competitive. Sales of Pentium 4 chips were very slow throughout 2001 and it appears that Intel predicted such scenario as in August 2001 it releases PC133 SDR SDRAM supporting 845 core-logic to popularize the platform, whereas in 2002 the company launched DDR SDRAM (PC-1600 and PC-2100) supporting 845 B-step core-logic.

Even in 2002, the time when Rambus memory was supposed to command a substantial part of the market, only several manufacturers (albeit, large ones, including Samsung Electronics, Micron, Elpida, etc) produced RDRAM and, according to iSuppli market tracking company, its share was around 5%.

It was pretty clear that SDR and DDR powered platforms were quickly gaining share of the Pentium 4 market, still, Intel 850 was “preferable” core-logic set for the NetBurst chip since dual-channel PC600/PC800 RDRAM memory sub-system provided 2.40GB/s or even 3.20GB/s peak bandwidth, just what the doctor ordered for Pentium 4’s 400MHz Quad-Pumped Bus with 3.20GB/s bandwidth.

Under the contract with Rambus Intel could not release a mainstream dual-channel DDR core-logic until 2003 as such chipset would directly compete against Intel’s Rambus platform. But by 2002 it was clear that Rambus memory is not the way to go: it was expensive, it had very high latencies, it was proprietary and its performance benefits were not distinct enough. As a result, in late 2002 Intel released its last and final RDRAM-supporting chipset – Intel 850E that supported PC1066 RDRAM along with 533MHz QPB – as well as E7205, which supported dual-channel PC-2100 memory with ECC and much lower latencies compared to RDRAM, 533MHz bus and was officially aimed only at workstation.

The share of Intel Pentium 4-based machines with Rambus inside was quickly dropping, but the final nail into the coffin of RDRAM on the PC market was hammered in Spring ’03 when Intel released its breed of 800-series chipsets supporting dual-channel DDR memory at up to 400MHz clock-speed providing bandwidth of up to 6.40GB/s. In fact, Intel wanted to forget RDRAM like a bad dream: at Intel Developer Forum Fall 2002 the company said it would rather not ratify 400MHz (PC3200) DDR memory, most probably because it did not need it as it wanted to introduce 667MHz QPB with its new processors due in 2003. But since AMD’s Athlon 64 was close, Intel decided to introduce chips with 800MHz quad-pumped bus that, by coincidence, required memory bandwidth that even single-channel PC1066 RDRAM simply could not provide at that time.

After Intel dropped RDRAM support, Silicon Integrated Systems wanted to get that premium market and even introduced its R658 and R659 chipsets that supported higher-speed RDRAM in quad-channel mode, but the market did not want to go with that memory standard and by the time DDR2 emerged in 2004, Rambus was already forgotten.

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