RAM is an acronym for Random Access Memory. It is also referred as main memory, primary memory or system memory. RAM is a type of computer memory that allows easy and quick access to the computer data randomly. Computer’s Read / Write memory is referred as RAM, since user can easily write and read the information for it and can easily reach any location (address given) within a short time.
RAM is a volatile memory i.e. the data stored on RAM can be accessed only the power in on. As and when the power goes off, data cannot be accessed.
RAM provides the random access to the data unlike CDs / DVDs which provides sequential access. Thus, with RAM data can be accessed faster and easier as compared to the sequential access. This is because, in case of sequential access to access a particular data each and every cell will be checked sequentially since the data will be stored in a sequential order. However, in RAM a particular memory cell can be accessed easily by knowing the row and column that intersects at that cell, without having to check all the cells to find a particular data.
Types of RAM:
DRAM (Dynamic RAM): DRAM can store data only for a very short time. Even if the power of ON, it loses its stored information. In DRAMs. The data will be stored using a transistor and capacitors and both together comprise a memory cell. Since, it stores data for a while; it needs to be refreshed constantly. The capacitors on DRAM hold the high or low charge (either 1 or 0) and the transistor acts as a switch that allows the control circuitry to read the capacitor’s state of charge or can even change its state. It is quite slower and less expensive, hence it is the predominant form of computer memory.
SRAM (Static RAM): In SRAM, a data bit is stored in a flip-flop state. SRAM can store data until the power is on and doesn’t need to be refreshed often. It uses multiple transistors, generally 4 or 6 for each memory cell but will not have a capacitor in each cell. It is primarily used in cache memory of the CPU. Generally SRAM is faster and even requires less power than DRAM, but are more expensive.
Other types of RAM:
Fast Page Mode RAM (FPM RAM): FPM RAM is a type of DRAM, with some updated features. It is capable of accessing the data that is on the same page with less latency. Earlier FPM memory is used in 486 and Pentium based systems.
Extended Data-Out RAM (EDO RAM): EDO RAM is just an improvement of DRAM since, it possess advanced timing features. The data storage time has been extended and the refresh rate is reduced, which increases the performance.
Synchronous DRAM (SDRAM): DRAM, FPM, and EDO are replaced by SDRAM. It synchronizes the data transfer process between the memory and CPU, thus improving the performance.
Double Data Rate RAM (DDR RAM): DDR RAM transfers the data twice for a single clock cycle. Hence, doubles the data rate and has become the memory standard
Double Data Rate 2 RAM (DDR2 RAM): DDR2 is the updated version of DDR RAM, but has the same data rate as DDR. It differs in the modified signaling that offers more resistance to noise and cross-talk between the signals along with higher speeds.