What is RAM

Computer Memory - Laptop Computer Memory - Memory Upgrade - Memory Upgrades - RAM Memory
RAM stands for Random Access Memory. Actually the main memory or primary storage is referred to as RAM. It consists of memory chips that can be read from and writtern to by the processor. When the computer is powered on, certain operating system files load into RAM from the storage device such as a hard disk. Then operating system remains in RAM as long as the computer has continuous power.

The control unit performs the following functions for main memory.

* Stores the data and instructions (entered from input unit) into the RAM (or main memory).
* Provides the data and instructions from main memory to other parts of the computer.
* Stores the processed results back into the RAM (or main memory).



The RAM plays very important role in data processing. The program and the data must be transferred to RAM before to run the program to process the data. The processor processes the data according to the program instructions by fetching the data and instructions from the RAM. The processor interprets and executes the program instructions while the program is in RAM. During this time the content of RAM may change. RAM can hold multiple programs simultaneously, provided the computer has enough RAM to accommodate all the programs. The program with which you are working usually is displayed on the screen. In Windows environment you can switch from one program to another.



The storage capcity of RAM or main memory is measured in bytes. A byte is a group of 8-bits. One character takes one byte of memory. The amount of data and program size are also measured in bytes.

1 Byte = 8-Bits
1 Kilo Byte = 1024 Bytes
1 Mega Byte = 1024 Kilo Bytes
1 Giga Byte = 1024 Mega Bytes
1 Tera Byte = 1024 Giga Bytes

The large RAM size increases the accessing speed of the computer. RAM plays an integral part in the internal operation of processor. Microcomputers come with different amounts of RAMs which are from 128MB to 2GB. Advertisements normally list the type of processor, the clock speed of the processor and the amount of RAM in the computer. More RAM means the computer can use powerful program with large size. It also improves the data processing speed of the computer.

Memory Module

RAM chip is smaller in size than the processor chip. A RAM consists of more than one chips. RAM chips usually reside on a memory module which is a small circuit board. Memory slots on the motherboard hold memory modules. There are three types of memory modules. There are:

SIMM SIMM stands for Single Inline Memory Module. It has pins of opposite sides of the circuit board that connect together to form a single set of contacts. A SIMM has RAM chips on only one side. Each SIMM can hold 4 MB to 128MB RAM.
DIMM DIMM stands for Dual Inline Memory Module. It has pins on opposite side of the circuit board that does not connect and thus form two sets of contacts. SIMM and DIMM hold the SDRAM chips. A DIMM has RAM chips on both sides.
RIMM

RIMM stands for Rambus Inline Memory Module. It holds the RDRAM chips.

The RAM is further divided into:

1. DRAM
2. SRAM

1. DRAM

DRAM stands for Dynamic Random Access Memory. DRAM is the most common type of RAM used to store data & instructions. In order to maintain data in DRAM chip, the chip is refreshed frequently (hundreds of time a second), otherwise data may be lost. During the refreshing process the CPU has to wait to read & write data in DRAM. It is because DRAM decreases the processing speed of the computer.

Today many DRAM chips exists and most of which are faster than the basic DRAM. The most important are:

SDRAM

SDRAM stands for Synchronous Dynamic RAM. SDRAM are much faster than basic DRAM chips because they are synchronized to the system clock. Often in computer ads, the speed of SDRAM is expressed in megahertz (MHz).

RDRAM

RMRAM stands for Rambus Dynamic RAM. It is faster and more expensive than SDRAM because it uses pipelining technique. It is used in Intel P4. Today most of PCs use SDRAM or RDRAM.

2. SRAM

SRAM stands for Static Random Access Memory. It is faster than DRAM because it does not have to be refreshed frequently and the CPU has not to wait to read & write data. SRAM chips however are more expensive than DRAM chips. Special applications such as cache use SRAM chips.