Hardware

SDRAM (Synchronous Dynamic Random Access Memory)

The term “Synchronous Dynamic Random Access Memory (SDRAM)” refers to a broad category of DRAM modules that rely on the signal sent by the system clock in order to coordinate their functioning with other internal PC components.

SDR SDRAM

A Single Data Rate Synchronous Dynamic Random Access Memory (SDR SDRAM) can read/write one word of data per clock cycle.

SDR SDRAM uses 168 contact pins.

DDR SDRAM

Characteristics of Double Data Rate Synchronous Dynamic Random Access Memory (DDR SDRAM) include:

  • 184 contact pins
  • Reads/writes 2 words of data per clock cycle
  • 1 notch on the module contact surface
Comparison of DDR SDRAM standards
Standard name DRAM cell array clock
(MHz)
Cycle time
(ns)
I/O bus clock
(MHz)
Data rate
(MT/s)
VDDQ
(V)
Module name Peak transfer rate
(MB/s)
Timings
(CL-tRCD-tRP)
DDR-200 100 10 100 200 2.5±0.2 PC-1600 1600
DDR-266 133.33 7.5 133.33 266.67 PC-2100 2133.33 2.5-3-3
DDR-333 166.67 6 166.67 333.33 PC-2700 2666.67
DDR-400A
DDR-400B
DDR-400C
200 5 200 400 2.6±0.1 PC-3200 3200 2.5-3-3
3-3-3
3-4-4

 

DDR2 SDRAM

Characteristics of Double Data Rate 2 Synchronous Dynamic Random Access Memory (DDR2 SDRAM) include:

  • Reads/writes 4 words of data per clock cycle
  • 1 notch on the module contact surface
  • 240 contact pins

The industry name for DDR2-1066 module is PC2-8500.

The total bandwidth of a DDR2-533 module is 4266 MB/s.

DDR3 SDRAM

Characteristics of Double Data Rate 3 Synchronous Dynamic Random Access Memory (DDR3 SDRAM) include:

  • Reads/writes 8 words of data per clock cycle
  • 1 notch on the module contact surface
  • 240 contact pins

The industry name for DDR3-1333 module is PC3-10600.

The total bandwidth of a DDR3-1600 module is 12800 MB/s.

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