A RAM (random access memory), is the main memory of the computer. It is volatile in nature, thus stores the information as long as power is supplied to it. Although all of our files, videos, apps, programs are stored on secondary storage such as HDD or SSD but they all are loaded to the RAM before being run on the computer system. It is also sometimes known as read/write memory. It is semiconductor storage.
There are mainly two types of RAM:
- SRAM or Static RAM
- DRAM or Dynamic RAM
SRAM : S-RAM or Static RAM keeps the data stored as long as power supply in on. It uses conventional flip-flops, which consists of two cross-coupled inverters, to store binary bit o or 1. It faster but expensive in comparison to the DRAM.
DRAM: D-RAM or Dynamic RAM loses its stored data after few milliseconds even if the power is on. The reason why it looses the data is, because it store information in the form of charge on a capacitor, which leaks away in very frequently. Thus, it requires periodically refreshing in order to charge the capacitor fully. It is cheaper and is widely used. It is asynchronous.
SDRAM: Synchronous DRAM (S-DRAM) uses the same clock as the CPU, which makes the memory chips ready to transfer data when CPU wants to do so. It runs at the memory bus without imposing wait state. It performs all actions on the rising edge of the clock signal.
DDR SDRAM : DDR means Double Data Rate. It is advanced SDRAM with Double data transfer rate. Unlike the regular SDRAM it transfers the data on both edges of the clock (hing / low). DDR2, DDR3, DDR4 and DDR5 are the latest of DDR. DDR3 is highly popular and is widely used in Mobile phones, servers and computers.