What are the differences in SDRAM, DDR1,DDR2, DDR3 and DDR4 RAM ?

SD RAM:

SDRAM-Synchronous Dynamic Random Access Memory. SDRAM synchronizes the memory speed with the CPU clock speed. The SDRAM depends on the speed of the CPU bus. The data transfer speed of the SDRAM is measured in nanoseconds and megahertz unit. It runs with an average speed of 133 MHz

Bus Clock Speed 100-166 MHz

Transfer Rate 0.8 – 1.3 GB/s

Internal Rate 100- 166 MHz

Number of Pins 166 pins

Density 64 MB, 128 MB, 256 MB, 512 MB

Voltage 3.3 Volt

DDR 1 :

DDR stand for Double Data Rate it is the latest version of SDRAM. DDR is synchronous with the system clock. The difference between SDRAM and DDR is that SDRAM transfer data on the rising edge of the clock signal. However, DDR transfer data on both edge of the clock signal that is on the rising and falling edges of the clock signal.

Some of the variations of the DDR RAM available in market are:

DDR 266, DDR 333, DDR 400

Bus Clock Speed 133 – 200 MHz

Transfer Rate 2.1 to 3.2

Internal Rate 133 to 200 MHz

Number of Pins 184 Pins

Density 512 MB, 1 GB

Voltage 2.5/2.6 Volt

DDR2 :

DDR2 is the second generation of Double Data Rate SDRAM memory. DDR2 Standards names are, DDR2 400B, DDR2 400C, DDR2 533B, DDR2 533C DDR2 667C, DDR2 667D, DDR2 800C, DDR2 800D, DDR2 800E, DDR2 1066E, DDR2 1066F. The DDR2 Ram has 240 Pins.

Bus Clock Speed 266 to 400 MHz

Transfer Rate 4.2 to 6.4 GB/s

Internal Rate 133 to 200 MHz

Number of Pins 240 Pins

Density 512 MB, 1GB, 2GB

Voltage 1.8 Volt

DDR3 :

DDR3 is the third generation of Double Data Rate SDRAM memory. Similar to DDR2, it is a continuing evolution of DDR memory technology that delivers higher speeds. The DDR3 memory module physically look similar to the DDR2

Bus Clock Speed 533 to 800

Transfer Rate 8.5 to 14.9

Internal Rate 133 to 200 MHz

Number of Pins 240 Pins

Density 1GB, 2GB, 4GB, 8GB, 16GB

Voltage 1.35/1.5 Volt

DDR4 :

Bus Clock Speed 1066 - 1600

Transfer Rate 17 – 21.3 GB/s

Internal Rate 133 to 200 MHz

Number of Pins 288 Pins

Density 4 GB to 128 GB

Voltage 1.2 Volt

Physical difference between DDR 1, DDR2, DDR3, DDR4 :-

Er. Ashok Yadav

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