Random Access Memory – cost-effective memory chips (integrated circuits) used extensively in computers to give fast access (compared to disks, tapes etc. – RAM has no moving parts) and very high data rates. RAM is available in several different forms and has been subjected to Moore’s Law for over three decades. When RAM chips first arrived they had a huge impact and, as they have grown in capacity and speed while unit price remains reasonably stable, their applications and importance have multiplied.
DRAM – Dynamic RAM. DRAM chips provide high density memories which must be powered and clocked to retain data. DRAM offers very speedy access to data and is vital for the fast computer performance and there is a large industry dedicated to the development and manufacture of ever faster and bigger DRAM chips. Synchronous DRAM (SDRAM) is faster and DRAM, and now DDR SDRAM (Double Data Rate) technology is increasing the performance of many of the newer PC and graphics products. Currently DDR3 clocking at 100 MHz can achieve data transfer rates of 6400 MB/s and allows storage capacity of 8 Gb per chip. DDR4 is on the way. Along with these performance breakthroughs power consumption is being reduced.
There are many more variations and versions of RAM to suit specific applications.
SRAM – Static RAM memory chips in general behave like dynamic RAM (DRAM) except that static RAMs retain data in a six-transistor cell only needing power to operate (DRAMs require clocks as well). Because of this, current available capacity is lower than DRAM – and costs are higher, but speed is also greater. SRAM is becoming increasingly popular as an alternative to hard disk drives in computers to achieve faster operation.
See also: Flash Memory