Types of Memory

EDO MEMORY

Once considered cutting edge, EDO is simply FPM DRAM that is been slightly modified to modestly boost performance. The modification allows one read to begin before the last one has been completed, and the overlap can increase raw transfer speed by 20 percent.

SDRAM

(Synchronous Dynamic Random Access Memory) has largely been superseded by DDR-SDRAM, but you still see SDRAM on some systems. For basic computing needs, you probably won't notice much of a performance difference between SDRAM and the faster DDR-SDRAM. But given DDR-SDRAM's popularity, the only reason to go with SDRAM is if it was the only choice on an otherwise desirable computer.

DDR1-SDRAM

(Double Data Rate Synchronous Dynamic Random Access Memory) is the dominant type of memory today. DDR refers to Double Data Rate, where data is sent both at the beginning and the end of each clock cycle, resulting in faster access speeds.
DDR SDRAM utilizes the existing SDRAM infrastructure and technology while doubling the nominal bandwidth available to systems. In plain English, imagine that PC133 SDRAM is like data going along a one way street. DDR SDRAM is like data going along a two lane highway, as DDR stands for Double Data Rate. What is this good for? Well, any application really. Everything uses RAM and therefore everything from the Operating System to intensive 3D gaming benefits from the increased speed of DDR SDRAM. DDR-SDRAM has another important improvement over PC133 SDRAM. Its voltage supply is only 2.5V, instead of 3.3V. This and the lower capacitances inside the memory chips lead to a significantly reduced power consumption, which makes DDR-SDRAM very attractive for notebooks.

DDR2 SODIMMS

For notebook-pc's offer a number of improvements over the previous DDR1 generation memory solution. These include a space-saving form factor, low power consumption, improved thermal characteristics, and high bandwidth. All this results in greater performance per watt and improved battery life compared to other memory standards.

DDR2 notebook SODIMMS are rated at 1.8 Volts, which is nearly a full Volt (0.8V) lower than DDR1 SODIMMs and feature IC's based on the FBGA process. This means that notebooks with DDR2 modules require up to 65% less voltage than those running DDR400, thus improving battery life. Samsung, a leading semiconductor manufacturer, ran internal tests and showed that a notebook PC equipped with Samsung DDR2 memory lasted close to 10% longer before requiring recharging. Notebooks with DDR2 memory bring this goal a step closer as the extra 10% battery life can improve mobility and thus productivity.