DDR和SDRAM的区别

SDRAM 的新变体是 DDR1、DDR2 和 DDR3。随机存取存储器DDR和SDRM都是用于计算机的存储器集成电路。

传统上，动态随机存取存储器 (DRAM)具有关联的异步接口，这表明它可以尽可能快地响应速度输入的变化。每个 SDRAM 和 DDR RAM 都有一个同步接口，这意味着它在响应调节输入之前等待时钟信号，从而与计算机的系统总线同步。

这允许硅芯片拥有比关联异步 DRAM 更先进的操作模式。这也是为什么 SDRAM 和 DDR RAM 的速度是以速率而不是纳秒 (ns) 为单位的原因。

SDRAM通常是指初始代同步 DRAM ，它比结果代 (DDR) 慢，因为每个时钟周期(单数据速率)仅传输 1 个知识字。

第二代同步 DRAM内存芯片是 DDR(有时称为 DDR1)。 DDR 代表双倍速率，表示芯片每个时钟周期读取或写入 2 个知识字。 DDR 接口通过在时钟信号的每个上升沿和下降沿读取和写入信息来实现这一点。此外，SDR 接口时间安排的一些细微变化是在 savvy 中创建的，因此提供电压从 3.3 V 降低到 2.5 V。因此，DDR SDRAM 不能向后兼容 SDR SDRAM。

DDR和SDRAM的区别：

SDRAM	DDR
It refers as synchronus dynamic random access memory	It refers as Double data rate SDRAM
SDRAM has 168 pins and two notches at the connector	DDR has 184 pins and a single notch at the connector.
SDRAM was released in 1997	DDR RAM was released in 2000
SDRAM has less speed in camparison DDR	DDR can transfer data at roughly twice the speed of SDRAM.
it’s working on 3.3 volts	it’s working on 2.5 Volts (standard); 1.8 V (low voltage)
SDRAM speed is considered as 66 MHz, 100 MHz, 133 MHz	DDR working on speed as 200 MHz, 266 MHz, 333 MHz, 400 MHz
SDRAM’s Internal rate range is (100 Mhz-166 Mhz)	DDR’s Internal rate range is(133 Mhz – 200 Mhz)
Data rate of SDRAM is (0.8-1.3) GB/s	Data rate of DDR is (2.1-3.2)
SDRAM prefetch timing is 1ns	DDR prefetch timing is 2ns
SDRAM is waiting wait for the completion of the previous command to be able to do another read/write operation.	DDR is not waiting wait for the completion of the previous command to be able to do another read/write operation.