DDR2 SDRAM (Double Data Rate two Synchronous Dynamic Random Access Memory) is a high-speed RAM used to store data when the computer is running. Besides being a part of the computer, DDR2 SDRAM is also used in other digital electronic devices.
DDR2 SDRAM and SDRAM family, is one of the results of implementation of DRAM technology. DDR2 SDRAM is the development of more advanced than its predecessor, the DDR SDRAM. DDR2 SDRAM main advantages lie in its ability to operate (run) the external data bus twice as fast as DDR SDRAM. This could be due to the improvement in the system's lawyer-Signal bus (bus signaling), and the operation of memory cells that are faster than DDR SDRAM, but, unfortunately, DDR2 will result in higher latency that can degrade the performance of the memory itself.
Not unlike SDRAM, DDR2 storing data on a storage unit memory cells which will then be activated by using a clock signal so that it works (runs) in unison with the external data bus. Like DDR, DDR2 also transmit data twice in one cycle pulse (clocok cycle), given the technology of DDR2 double data rate (dual pumped, pumped double, or double transition), when the clock signal curve is high and when the curve clock signal is dropped. Principal difference between DDR and DDR2 is:
Buses on DDR2, beating twice the speed of the memory cells, so it can transfer data four bits per memory cell cycle. Compare with DDR are only able to transfer two bits per memory cell cycle. Effectively, the DDR2 bus can run twice the bus speed of DDR.
DDR2 to work at a lower voltage than DDR. If DDR is designed to work at a voltage of 2.5 volts, then the voltage of DDR2 is designed to work at 1.8 Volts.
DDR2 SDRAM modules used in desktop PCs are generally of type DIMM (Dual In-line Memory Module), has 240 pins. In the row of pin holes there is one notch (notch). The hole is in the notch in the middle row of pins, similar to the position of the notch on DDR SDRAM holes, but the position of the notch on DDR2 SDRAM hole more towards the center. Compare with SDRAM has two notches hole.
The notch hole is useful to prevent each type of DRAM are not interchangeable, since each type of DRAM are not mutually compatible. Due to differences in the notch hole, then the SDRAM module will not fit (can not) be included or inserted in a slot or slots DDR2 SDRAM DDR2 SDRAM. In contrast, DDR2 SDRAM modules are not suitable for inclusion or inserted in the slot SDRAM and DDR SDRAM slots.
- DRAM (Dynamic Random Access Memory)
- FPM DRAM (Fast Page Mode DRAM)
- EDO RAM (Extended Data Out RAM)
- SDRAM (Synchronous Dynamic Random Access Memory)
- RD RAM (Rambus Dynamic Random Access Memory)
- DDR SDRAM (Double Data Rate Synchronous Dynamic Random Access Memory)
- DDR3 SDRAM (Double Data Rate three Synchronous Dynamic Random Access Memory)
- DDR4 SDRAM (Double Data Rate four Synchronous Dynamic Random Access Memory)
- SRAM (Static RAM)
- VRAM (Video Random Access Memory)
- SGRAM (Synchronous Graphics RAM)