Random-access memory (usually known by its acronym, RAM) , is the best known form of computer memory. RAM is considered “random access” because you can access any memory cell directly if you know the row and column that intersect at that cell.

The word RAM is mostly associated with volatile types of memory where the information is lost after the power is switched off.

Some Types of ram :

• SRAM: Static random access memory uses multiple transistors It is used primarily for cache.
• DRAM: Dynamic random access memory has memory cells with a paired transistor and capacitor requiring constant refreshing.
• FPM DRAM: Fast page mode dynamic random access memory 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.
• EDO DRAM: 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.
• SDRAM: Synchronous dynamic random access memory takes advantage of the burst mode concept to greatly improve performance. It does this by staying on the row containing the requested bit and moving rapidly through the columns, reading each bit as it goes. The idea is that most of the time the data needed by the CPU will be in sequence.
• DDR SDRAM: Double data rate synchronous dynamic RAM is just like SDRAM except that is has higher bandwidth, meaning greater speed.
• RDRAM: Rambus dynamic random access memory is a radical departure from the previous DRAM architecture. What makes RDRAM so different is its use of a special high-speed data bus called the Rambus channel. 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. To help dissipate the excess heat Rambus chips are fitted with a heat spreader, which looks like a long thin wafer.there are also SO-RIMMs, designed for notebook computers.
• VRAM: VideoRAM, also known as multiport dynamic random access memory (MPDRAM), is a type of RAM used specifically for video adapters or 3-D accelerators. VRAM is located on the graphics card and comes in a variety of formats, many of which are proprietary. The amount of VRAM is a determining factor in the resolution and color depth of the display. VRAM is also used to hold graphics-specific information such as 3-D geometry data and texture maps. True multiport VRAM tends to be expensive, so today, many graphics cards use SGRAM (synchronous graphics RAM) instead. Performance is nearly the same, but SGRAM is cheaper.

Stumble! for WP