Memory devices are used to store data and information. Computer memories are mainly classified into three types – primary memory, secondary memory, and cache memory. The primary memory is further classified into two types namely – RAM and ROM, where RAM is further subdivided into two types -SRAM and DRAM.
What is RAM?
RAM stands for Random Access Memory. It is the internal memory of the CPU for storing data, program, and program result. It is a read/write memory which stores data until the computer is working. As soon as the computer is switched off, data is erased. Therefore, RAM is a volatile memory.
What is SRAM?
SRAM stands for Static Random Access Memory. Each memory cell of SRAM is made up of a flip-flop, a 1-bit storage device. SRAM uses a matrix of 6 transistors. In this memory circuit, capacitors are not used. Thus, in SRAM, there is no data leakage, so SRAM need not be refreshed regularly.
SRAM is a high speed random access memory which is used in special applications such as cache memory in computers and other embedded systems. However, SRAM is relatively expensive because it uses comparatively more number of chips that increase its manufacturing cost. SRAM is a volatile memory which means it retains the stored data as long as the power is supplied to the computer.
What is DRAM?
DRAM stands for Dynamic Random Access Memory. Each memory cell of DRAM is made up of one transistor and one capacitor. In DRAM, the data and information is stored in the form of an electric charged on the capacitor. Since capacitor loses its data (charge), thus DRAM must be continually refreshed several hundred times per second to maintain the data.
DRAM is a small sized and less expensive type of RAM. For this reason, it is used as RAM in most computer systems. However, DRAM is relatively slower and has a short data life than SRAM.
