RDRAM memory

RDRAM: RDRAM (Rambus DRAM) is a kind of memory developed by RAMBUS in the United States. Unlike DDR and SDRAM, it uses a serial data transfer mode. When it was launched, because it completely changed the transmission mode of the memory, it could not guarantee compatibility with the original manufacturing process, and the memory manufacturer must pay a certain patent fee to produce RDRAM, plus its own manufacturing cost, which led to The high price of RDRAM has been unacceptable for ordinary users since its introduction. At the same time, DDR can gradually become the mainstream at a lower price and good performance. Although RDRAM has received strong support from Intel, it has never become the mainstream.

The data storage bit width of RDRAM is 16 bits, which is much lower than the 64 bits of DDR and SDRAM. But in terms of frequency, it is much higher than the two, which can reach 400MHz or even higher. Similarly, data is transmitted twice in one clock cycle, and data can be transmitted once in the rising period and falling period of the clock, and the memory bandwidth can reach 1.6Gbyte/s.

The information of the ordinary DRAM line buffer is no longer retained after being written back to the memory, while RDRAM has the characteristic of continuing to maintain this information, so when the memory is accessed, such as the line buffer has been If there is target data, it can be used, thus realizing high-speed access. In addition, the data can be collected and transmitted in packets, so as long as 24 clocks are used initially, 1 byte can be read out every 1 clock in the future. The data length that can be read in one visit can reach 256 bytes.

Direct Rambus dynamic random access memory (DRDRAM) provides a 2-byte (16-bit) bus instead of the 8-bit bus of DRAM. With a random access memory speed of 800 MHz (800 million cycles per second), the highest data transfer rate is 1.6 billion bytes per second. Direct Rambus uses pipelined flow operations to move data from random access memory to buffer memory closer to the level of the microprocessor or display. Eight operations may be performed simultaneously. Rambus is designed to fit existing motherboard standards. The component inserted into the motherboard connection is called Rambus Embedded Memory Modulus (RIMM). They can replace the traditional dual embedded memory modules.

Because it cannot be used individually, it must be used in pairs. Now it has been withdrawn from the market. An alternative to DRDRAM is SyncLink DRAM (SLDRAM).