RAM (Random Access Memory) (Primary or Main memory)

RAM (Random Access Memory) (Primary or Main memory)

It is a volatile (data will lose when power off) memory, processor can directly access the content of RAM, it is the memory area where the currently running data stored, RAM is like a table, if the table has more area, we can open a number of books at a time, like the same way if our RAM's size is more we can open a number of files or applications at a time . It is generally classified into two.

1. Static RAM(SRAM)
2. Dynamic RAM(DRAM)

I. Static RAM(SRAM)

Stores data until power is on, used for special purposes, it is the fastest memory, expensive. This RAM is inbuilted .
eg: cache memory (memory between processor and RAM)

II. Dynamic RAM(DRAM)

As its name it is dynamic means its data will refresh periodically (within milliseconds) even when the power is on.We add this RAM in RAM slots in motherboard.
According to the working DRAMs are classified into three.

1. SIMM (Single Inline Memory Module)
2. DIMM (Dual Inline Memory Module)
3. RIMM (Rambus Inline Memory Module)

I. SIMM (Single Inline Memory Module)

This transfer data through single side of memory module. Pins on either sides are connected to eachother, this memory is used in early days, they are mainly two types 8bit(have 30pins) and 32 bit(have 72pins).

II. DIMM (Dual Inline Memory Module)

Most popular and widely using RAM, they transfer data through both sides of the memory module, have 64bit data transfer rate. DIMMs are classified into two 1. SD RAM 2. DDR RAM.

1. SDRAM(Synchronous DRAM)

They have 168 pins and two notchs(small cut on edge) , transfer data through both side, they are not using today.

2.DDR RAM(Double Data Rate RAM)

Most popular, fastest RAMs, used today, they are three types

1. DDR1 - have 184 pins and one notch
2.DDR2 - have 240pins and one notch
3.DDR3 (latest) - have 240pins and one notch
all have only one notch but its positioning is different and cannot use a DDR1 RAM in DDR2 Slot or DDR3 slot and vice versa ie: they cannot use interchangingly, each support only its corresponding slot in motherboard.

III. RIMM(Rambus Inline Memory Module)

This technology is used by Rambus co-operation, they are same as DIMMs except they are faster, have 184pins, 2notches but RIMMs are very expensive and not widely used.

RAM size is expressed in Megabytes(MB) or Gigabytes(GB),today commonly using RAM sizes in PCs are 1GB, 2GB, 3GB and 4GB, more can also use for powerful PCs.