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Review
In this section we would study about the features of RAM, structure of memory module, different kinds of RAM, current RAM technology, advantages and disadvantages of different kinds of RAM, we will also look the packaging part of RAM chips and what are the things that we should consider to improve memory performance or in other words increase the efficiency of RAM.
RAM, or Random Access Memory, is "volatile." This means that it only holds data while power is present. RAM changes constantly as the system operate, providing the storage for all data required by the operating system and software. Because of the demands made by increasingly powerful operating systems and software, system RAM requirements have accelerated dramatically over time. For instance, at the turn of the millennium a typical computer may have only 128Mb of RAM in total, but in 2007 computers commonly ship with 2Gb of RAM installed, and may include graphics cards with their own additional 512Mb of RAM and more.
Facts on Memory "RAM "
Storing and retrieving data from a large block of memory is more time-consuming than from a small block. With a large amount of memory, the difference in time between a register access and a memory access is very great, and this has resulted in extra layers of cache in the storage hierarchy.
When accessing memory, a fast processor will demand a great deal from RAM. At worst, the CPU may have to waste clock cycles while it waits for data to be retrieved. Faster memory designs and motherboard buses can help, but since the 1990s "cache memory" has been employed as standard between the main memory and the processor. Not only this, CPU architecture has also evolved to include ever larger internal caches. The organisation of data this way is immensely complex, and the system uses ingenious electronic controls to ensure that the data the processor needs next is already in cache, physically closer to the processor and ready for fast retrieval and manipulation.
SRAM and DRAM play bigger role in this process.
Static RAM (SRAM):
Static Random Access Memory, it is constructed from thousands of Flip-Flop circuits,it does not required regular refresh options, it is faster than DRAM but is more expensive,SRAM uses six transistors to hold 1 bit because of this the density reduces hence the consumption of power is more. It is the part of L2 cache (external) as it has good speed.
DRAM (DYNAMIC RAM):
This was used first in personal computers; it achieves a good speed and density. It is simple and relatively less expensive to produce. A single transistor and capacitor is used to hold a bit. The contents have to be refreshed every few milliseconds or the contents of each bit location will decay. DRAM’s are rated by their storage capacity(1 M-Bit to 64 M-Bit) and their access speed ranges from 150 ns to 50 ns.
Different types of SRAM and DRAM
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