System DRAM Technologies

DRAM Technology Types

As discussed earlier, DRAM was originally created to act as a fast middle-man to slow storage devices. Once the small section of data actually being used was offloaded into memory, it could work with the microprocessor much faster and nearly eliminate delays.

As time passed, however, hard disks and microprocessors began to hit the market in faster and faster models, to the point where the DRAM itself could be considered a major bottleneck. In order to eliminate that bottleneck, DRAM itself needed to evolve.

Today, there are 10 different commercially available types of system DRAM (excluding parity / ECC functions).

Page Mode DRAM - (DRAM)

The first brand of DRAM. It provided a fine solution for ancient ISA Video cards and 286-486 PCs. However, when the performance of CPU's began to increase more rapidly, it was quickly thrown out to make way for faster and more efficient DRAM technology.

Fast Page Mode DRAM - (FPM DRAM)

The first popular redesign of DRAM used a new feature called Fast Page Mode, which by default receives performance gains if the next access is identical or concurrent to the prior access. This form of DRAM was also manufactured at sub 60 ns ratings for various video cards.

Extended Data Output DRAM - (EDO DRAM)

EDO DRAM provides another performance boost by decreasing latency timing and providing quicker sequential reads. EDO DRAM is also seemingly more capable of handling 60 ns, which makes it ideal for 66 MHz motherboards.

Burst Extended Data Output DRAM - (BEDO DRAM)

BEDO provided a performance increase much like the small evolution that Fast Page mode does. BEDO improves over EDO by allowing bursts of data to be read, rather than one set at a time. It is hard to find, however, as it was only useable with certain 3rd party chipsets, and quickly overshadowed by SDRAM.

Enhanced DRAM - (EDRAM)

An older product from Enhanced Memory Systems, inc. It combines SRAM caches with FPM DRAM to provide excellent performance for 50 MHz bus speeds. By hiding DRAM charge time, it also improves page miss latency.

Multibank (Burst) Extended Data Output Enhanced DRAM - (Multibank EDO EDRAM) (Multibank BEDO EDRAM)

A specific product available from Enhanced Memory Systems, Inc. It combines the multibank SRAM caches of MDRAM with the read/write advancements of EDO/BEDO DRAM, combined into a SIMM/DIMM package for system memory.