Direct Rambus DRAM or DRDRAM (sometimes just called Rambus DRAM or RDRAM) is a type of synchronous dynamic RAM, designed by the Rambus Corporation. Image File history File links Broom_icon. ... Dynamic random access memory (DRAM) is a type of random access memory that stores each bit of data in a separate capacitor within an integrated circuit. ... DRAM is a type of random access memory that stores each bit of data in a separate capacitor. ... DRAM is a type of random access memory that stores each bit of data in a separate capacitor. ... DRAM is a type of random access memory that stores each bit of data in a separate capacitor. ... This article or section does not cite any references or sources. ... This article or section does not cite any references or sources. ... DDR SDRAM or double-data-rate synchronous dynamic random access memory is a type of memory integrated circuit used in computers. ... “DDR2” redirects here. ... This article does not cite any references or sources. ... Virtual Channel Random Access Memory (VC-RAM in short, other names such as VC-SDRAM, VCSDRAM, VCDRAM, or VCM) was a proprietary type of SDRAM produced by NEC which NEC called it as an open standard, with no licensing fees associated with VCM. VCM creates a state in which the... XDR DRAM is a high performance RAM Interface like SDR-SDRAM and DDR-SDRAM. The XDR solution was engineered to be effective in small high-bandwidth consumer systems, high-performance main memory applications, and flagship GPUs. ... VRAM an acronym for Video RAM. Generally a term used in computers to describe RAM dedicated to the purpose of displaying bitmap graphics in raster graphics hardware. ... Window RAM or WRAM is an obsolete type of semiconductor computer memory that was designed to replace video RAM (VRAM) in graphics adapters. ... Synchronous Graphics random accsess memory SGRAM is based on SDRAM, but includes graphics-specific read/write functions SGRAM also retrieves blocks of data and so reduces the number of reads and writes that memory must carry out. ... DDR2 SDRAM (Double Data Rate Two Synchronous Dynamic Random Access Memory) is a computer memory technology that, as of 2005, is becoming the mainstream standard for personal computer memory. ... GDDR3 (Graphics Double Data Rate, version 3) is a graphics card-specific memory technology, designed by ATI Technologies. ... This article does not cite any references or sources. ... GDDR5 (Graphics Double Data Rate, version 5) is a type of graphics card memory. ... Dram can mean several things: Dram (unit), an imperial unit of volume Dram, an imperial unit of weight or mass, see avoirdupois and apothecaries system Ottoman dram, a unit of weight, see dirhem Armenian dram, a monetary unit DRAM, a type of RAM Category: ... This article is about the company. ...

Implementation

Personal Computers

The first PC motherboards with support for RDRAM debuted in 1999. They supported PC-800 RDRAM, which operated at 400 MHz and delivered 1600 MB/s of bandwidth over a 16-bit bus using a 184-pin RIMM form factor. Data is transferred on both the raising and the falling edges of the clock signal (double data rate). This was significantly faster than the previous standard, PC-133 SDRAM, which operated at 133 MHz and delivered 1066 MB/s of bandwidth over a 64-bit bus using a 168-pin DIMM form factor. A megahertz (MHz) is one million (106) hertz, a measure of frequency. ... ReBoot character, see Megabyte (ReBoot). ... -1... Form factor refers to the linear dimensions and configuration of a device as distinguished from other measures of size (for example Gigabytes; a measure of storage size): in computing, form factor is used to describe the size and format of PC motherboards (see AT, ATX, BTX), but also of hard... In computing, a computer bus operating with double data rate transfers data on both the rising and falling edges of the clock signal. ... This article or section does not cite any references or sources. ... Two types of DIMMs: a 168-pin SDRAM module (top) and a 184-pin DDR SDRAM module (bottom). ...

RDRAM memory with integrated heatsink.

Moreover, if you have a mainboard with dual- or quad-channel memory subsystem, you have to upgrade all the channels at once. 16-bit modules provide one channel of memory, while 32-bit ones provide two. Therefore, if you have a dual channel mainboard accepting 16-bit modules, you have to add or remove RIMMs in pairs. If you have a dual channel mainboard accepting 32-bit modules, you can add or remove single RIMMs as well. Image File history File links Download high-resolution version (1774x450, 160 KB) Summary Photo by 68. ... Image File history File links Download high-resolution version (1774x450, 160 KB) Summary Photo by 68. ... Dual-channel architecture DDR/DDR2 SDRAM describes a motherboard technology that effectively doubles data throughput from RAM to the memory controller. ...

Stick/module specification

• PC600: 16-bit, single channel RIMM, specified to operate at 300 MHz clock speed, 1200 MB/s bandwidth
• PC700: 16-bit, single channel RIMM, specified to operate at 355 MHz clock speed, 1420 MB/s bandwidth
• PC800: 16-bit, single channel RIMM, specified to operate at 400 MHz clock speed, 1600 MB/s bandwidth
• PC1066 (RIMM 2100): 16-bit, single channel RIMM specified to operate at 533 MHz clock speed, 2133 MB/s bandwidth
• PC1200 (RIMM 2400): 16-bit, single channel RIMM specified to operate at 600 MHz clock speed, 2400 MB/s bandwidth
• RIMM 3200: 32-bit, dual channel RIMM specified to operate at 400 MHz clock speed, 3200 MB/s bandwidth
• RIMM 4200: 32-bit, dual channel RIMM specified to operate at 533 MHz clock speed, 4200 MB/s bandwidth
• RIMM 4800: 32-bit, dual channel RIMM specified to operate at 600 MHz clock speed, 4800 MB/s bandwidth
• RIMM 6400: 32-bit, dual channel RIMM specified to operate at 800 MHz clock speed, 6400 MB/s bandwidth

Video Game Consoles

Rambus's RDRAM saw use in several video game consoles, beginning in 1996 with the Nintendo 64. The Nintendo console utilized 4 MiB RDRAM running with a 500 MHz clock on an 8-bit bus, providing 500 MB/s bandwidth. RDRAM allowed N64 to be equipped with a large amount of memory bandwidth while maintaining a lower cost due to design simplicity. RDRAM's narrow bus allows circuit board designers to use simpler design techniques to minimize cost. The memory, however, was disliked for its high RAM access latencies. In the N64, the RDRAM modules are cooled by a passive heatspreader assembly.[15] The Nintendo 64 ), often abbreviated as N64, was Nintendos third home video game console for the international market. ... The three-letter acronym MIB may refer to any of several concepts: Management information base, a computing information repository used (for example) by SNMP In marbles, any marble, but esp. ...

Sony uses RDRAM in the PlayStation 2. The PS2 was equipped with 32 MiB of the memory, and implemented a dual-channel configuration resulting in 3200 MB/s available bandwidth. The PS3 utilizes 256 MiB of Rambus's XDR DRAM, which could be considered a successor to RDRAM, on a 64-bit bus at 400 MHz with an octal data rate^[1] (cf. double data rate) providing speeds of 3.2 GHz, allowing a large 204.8 Gbit/s (25.6 GB/s) bandwidth.^[2] “PS2” redirects here. ... XDR DRAM is a high performance RAM Interface like SDR-SDRAM and DDR-SDRAM. The XDR solution was engineered to be effective in small high-bandwidth consumer systems, high-performance main memory applications, and flagship GPUs. ... In computing, a computer bus operating with double data rate transfers data on both the rising and falling edges of the clock signal. ...

Video Cards

Cirrus Logic implemented RDRAM support in their Laguna graphics chip, with two members of the family; the 2D-only 5462 and the 5464, a 2D chip with 3D acceleration. RDRAM offered a cost-advantage while being potentially faster than competing DRAM technologies with its high bandwidth. The chips were used on the Creative Graphics Blaster MA3xx series, among others. Creative Technology Limited (SGX: C76, NASDAQ: CREAF) is a listed manufacturer of computer multimedia products based in Singapore where the firm was initially founded by Sim Wong Hoo (born 1955) on July 1, 1981. ...

Performance

Compared to other contemporary standards, Rambus shows significantly increased latency, heat output, manufacturing complexity, and cost. Some criticized RDRAM's larger die size, which is required to house the added interface and results in a 10-20 percent price premium at 16-megabit densities and adds about a 5 percent penalty at 64M.[16] RAM Latency is the amount of wait time that a computer experiences when trying to access data in its RAM. RAM latency is measured in front side bus clock cycles. ...

PC-800 RDRAM operated with a latency of 45 ns, which was more latency than other comparable DRAM technologies of the time. RDRAM memory chips also put out significantly more heat than SDRAM chips, necessitating heatspreaders on all RIMM devices. RDRAM includes a memory controller on each memory chip, significantly increasing manufacturing complexity compared to SDRAM, which used a single memory controller located on the northbridge chipset. RDRAM was also two to three times the price of PC-133 SDRAM due to a combination of high manufacturing costs and high license fees.^{[citation needed]} PC-2100 DDR SDRAM, introduced in 2000, operated with a clockspeed of 133 MHz and delivered 2100 MB/s over a 64-bit bus using a 184-pin DIMM form factor. To help compare orders of magnitude of different times this page lists times between 10−9 seconds and 10−8 seconds (1 nanosecond and 10 nanoseconds) See also times of other orders of magnitude. ... A large copper heatsink. ... This article or section does not cite any references or sources. ... DDR SDRAM or double-data-rate synchronous dynamic random access memory is a type of memory integrated circuit used in computers. ...

When installing multiple RIMMs on a memory channel, performance impact is greater than SDRAM design because the chips in the further memory module has to travel across all memory chips installed physically closer to the memory controller, instead of just 1 or 2 chips in production SDRAM motherboards.

The design of many common Rambus memory controllers dictated that memory sticks be installed in sets of two. Any remaining open memory slots must be filled with CRIMMs. These sticks provide no extra memory, and only served to propogate the signal to termination resistors on the motherboard instead of providing a dead end where signals would reflect. The picture on the lower right depicts a CRIMM stick. RDRAM motherboards require that all RIMM slots be populated. ...

A RAMBUS Continuity-RIMM (CRIMM), also known as terminator or dummy.

With the introduction of the i840 (Pentium III), Intel 850 (Pentium 4), Intel 860 (Pentium 4 Xeon) chipsets, Intel added support for dual-channel PC-800 RDRAM, doubling bandwidth to 3200 MB/s by increasing the bus width to 32-bit. This was followed in 2002 by the i850E chipset, which introduced PC-1066 RDRAM, increasing total dual-channel bandwidth to 4200 MB/s. Then in 2002, Intel released the E7205 Granitebay chipset, which introduced dual-channel DDR support for a total bandwidth of 4200 MB/s, but at a much lower latency than competing RDRAM. Image File history File links Download high-resolution version (1740x316, 101 KB) Summary Photo by 68. ... Image File history File links Download high-resolution version (1740x316, 101 KB) Summary Photo by 68. ... This is a list of computer motherboard chipsets made by Intel. ... This is a list of computer motherboard chipsets made by Intel. ... This is a list of computer motherboard chipsets made by Intel. ...

To achieve RDRAM's 800 MHz speed, the memory module only runs on 16-bit bus, instead of 64-bit bus in contemporary SDRAM DIMM. Furthermore, not all production RDRAM module at the time of Intel 820 launch can run at 800 MHz, but rather at slower speed.

Benchmarks

Benchmark tests conducted in 1998 showed most applications run slower with RDRAM. Although RDRAM was shown to be slightly faster than SDRAM alternatives in UMA solution, Intel 820 was not a low-end product, and no low-end products using RIMM has ever been made, so the advantage is useless for end users.[17]

In 1999, benchmark for Intel 840, Intel 820, Intel 440BX showed the performance gain (if any) from using Rambus chipsets do not justify its premium price over 440BX chipsets with PC-133 SDRAM except for workstation use.[18]

Later in 2002, it was shown that single channel DDR400 SDRAM modules, coupled with SiS648, can closely match against dual channel 1066 MHz RDRAM setup with Intel 850E in real-life applications[19]. Furthermore, there were upcoming chipsets that can use dual channel DDR400 SDRAM modules.

History of RDRAM marketing in PC market

In 1996-11, Rambus entered into a development and license contract with Intel.^[3]. After Intel had announced to the Wintel development community that it would only support the Rambus memory interface for its microprocessors,^[4] Intel was granted rights to purchase 1M shares of Rambus's stock at $10 per share.^[5] A microprocessor is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). ...

In 1998, Intel planned to make a $500 million equity investment in Micron Technology, to accelerate the adoption of Direct RDRAM.^[6] Other investment included paying $100 million to Samsung Electronics in 1999.^[7] Micron Technology (Micron) NYSE: MU is a multinational company based in Boise, Idaho, USA, best known for producing many forms of semiconductor devices. ... Samsung Group is one of the largest South Korean business groupings. ...

As a transition strategy, Intel planned to support PC-133 SDRAM DIMM on future Intel 82x chipset using Memory Transfer Hub (MTH).^[8] In 2000, Intel recalled Intel 820 motherboard with memory translator hub (MTH) because the MTH can, while doing simultaneous switching, produce noise that may cause the computer to hang mysteriously or to spontaneously reboot.^[9] Since then, no production Intel 820 motherboards contain MTH. Associated with all electronic circuits is noise. ...

In 2000, Intel subsidized RDRAM by bundling retail boxes of Pentium 4 CPU with 2 RIMMs.^[10] Intel began to phase out Rambus subsidies in 2001.^[11]

In 2003, Intel introduced Intel 865 and Intel 875 chipsets, which were marketed as high end replacement of Intel 850. Furthermore, the future memory roadmap did not include Rambus.^[12]

Few DRAM manufacturers have ever obtained the license to produce RDRAM, and those who did license the technology failed to make enough RIMMs to satisfy PC market demand, causing RIMM to be priced higher than SDRAM DIMMs, even when memory prices skyrocketed during 2002.^[13] During RDRAM's decline, DDR continued to advance in speed while, at the same time, it was still cheaper than RDRAM. While it is still produced today, few motherboards support RDRAM. Between 2002-2005, market share of RDRAM had never gone beyond 5%.^[14]

In 2004, it was revealed that Infineon, Hynix, Samsung, Micron, and Elpida had entered into a price-fixing scheme during 2001.^[15] The offending parties pleaded guilty and were fined afterwards. One theory for the motives of the major memory manufacturers is that back in the introduction of Intel 820, Intel decided to use RDRAM exclusively on future products, but because of RDRAM's high price, the plan failed. Rambus officials tried to recoup the losses by filing lawsuits against major memory manufacturers starting in year 2000, and claimed SDRAM, DDR SDRAM (and later DDR2, GDDR2, GDDR3) as Rambus's intellectual property, and forcing memory makers into paying royalties. Infineon Technologies is a German manufacturer of integrated circuits and related products. ... Hynix Semiconductor Inc. ... Elpida is a two-times entrant to the Eurovision Song Contest. ... DDR2 SDRAM or double-data-rate two synchronous dynamic random access memory is a computer memory technology. ... GDDR3 (Graphics Double Data Rate, version 3) is a graphics card-specific memory technology, designed by ATI Technologies. ... For the 2006 film, see Intellectual Property (film). ...

In 2007, the Federal Trade Commission was involved in legal action to limit the royalties paid to Rambus on the grounds that Rambus had characteristics of a monopoly and withheld patent information from the Joint Electron Device Engineering Council while they were developing DRAM. As at March 2007, this was still under appeal.^[16] | logo_caption = | seal = US-FederalTradeCommission-Seal. ... A monopoly (from the Greek language monos, one + polein, to sell) is defined as a persistent market situation where there is only one provider of a product or service, in other words a firm that has no competitors in its industry. ... JEDEC stands for Joint Electron Device Engineering Council and is the semiconductor engineering standardization body of the Electronic Industries Alliance (EIA), a trade association that represents all areas of the electronics industry. ...

See also

• List of device bandwidths

This is a list of device bandwidths: the channel capacity (or, more informally, bandwidth) of some computer devices employing methods of data transport is listed by bit/s, kilobit/s (kbit/s), megabit/s (Mbit/s), or gigabit/s (Gbit/s) as appropriate and also MB/s or megabytes per...

External links

• RDRAM on the Rambus website
• Reference where information about dual-channel RDRAM in the PS2 can be found

• How to install RAMBUS memory
• Illustrated Guide for Installing RDRAM

References

1. ^ Rambus.com Octal data rate
2. ^ Rambus.com XDR
3. ^ [1]
4. ^ [2]
5. ^ [3]
6. ^ [4]
7. ^ [5]
8. ^ [6]
9. ^ [7]
10. ^ [8]
11. ^ [9]
12. ^ [10]
13. ^ [11]
14. ^ [12]
15. ^ [13]
16. ^ [14]