Outline

• Introduction .• RAM types .• DRAM .• SRAM .

IntroductionRAM “Random Access Memory” is a form

of data storage that can be accessed randomly at any time, in any order and from any physical location., allowing quick access.

RAM is volatile i.e. its contents are lost when the device is powered off.

RAM allows the computer to read data quickly to run applications. It allows reading and writing.

RAM typesThe two main types of RAM are static RAM and dynamic RAM.Static RAM (SRAM)

4 times more expensive Very low access time . Information stored on

RS flip-flops . No need for refreshing . They made of

transistors it is used in cache . They can be either

Bipolar or MOS technology .

Dynamic RAM (DRAM) Low cost . Consumes less power . Information stored on

FET transistors . Needs to be refreshed . These are mostly made

of capacitors . it is used in main

memory These are available

only in MOS technology

RAM types

FPM RAM• Fast Page Mode Dynamic Random Access Memory It was the original form of DRAM. It waits through the entire process of locating a bit of data by column and row and then reading the bit before it starts on the next bit. Maximum transfer rate to L2 cache is approximately 176 Mbps.

EDO RAM• Extended data-out Dynamic Random Access Memory does not wait for all of the processing of the first bit before continuing to the next one. As soon as the address of the first bit is located, EDO DRAM begins looking for the next bit. It is about five percent faster than FPM. Maximum transfer rate to L2 cache is approximately 264 Mbps.

SDRAM • Synchronous DRAM .

• SDRAM is a type of dynamic random access memory which is synchronized with the clock speed that the microprocessor is optimized for. SDRAM is about five percent faster than EDO RAM and is the most common form in desktops today. Maximum transfer rate to L2 cache is approximately 528 Mbps.

DDR RAM• Double data rate synchronous dynamic RAM is just like SDRAM except that is has higher bandwidth, meaning greater speed. It is a newer variant of SDRAM. Maximum transfer rate to L2 cache is approximately 1,064 Mbps .

DDR2 RAM • Double Data Rate 2 .

• newer version of DDR .• twice as fast as the original DDR RAM.• 2003 .• still is double data rate just like the original DDR.• DDR2-RAM has modified signaling which enables higher speeds to be achieved with more immunity to signal noise and cross-talk between signals .

RDRAM• Rambus dynamic random access memory : Designed by Rambus, RDRAM uses a Rambus in-line memory module (RIMM), which is similar in size and pin configuration to a standard DIMM. RDRAM memory chips work in parallel to achieve a data rate of 800 MHz, or 1,600 Mbps. Since they operate at such high speeds, they generate much more heat than other types of chips .

REFERANCE• http://www.diffen.com/difference/RAM_vs_ROM

• http://en.wikipedia.org/wiki/Random_access_memory• https://www.google.ps/search?tbm=isch&q=compar

e+between+type+of+DRAM+&ei=Lxk0VaDUB4HasgH0qISoBg#imgrc=_

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