Computer’s memory is classified into primary memory and secondary memory.
Primary Memory: Random Access Memory (RAM) is an internal memory chip where data is stored temporarily when applications are running. It is a volatile memory and can written and read. If your program MS word is large, such as MS Word or Photoshop, you might notice that it takes a while to load. This is because it is being brought from your computer’s hard drive where it is stored into RAM. From here the processor can rapidly respond to instructions, as the program is immediately accessible in RAM.
Read Only Memory (ROM) is non volatile or permanent memory stores data or instructions that need to be permanent. Permanent memory is used to store the process that the computer needs to go through when it is switched on. ROM retains its contents when the power is switched off. The important use of ROM is to store to software that allows a machine start up successfully, this software is known as BIOS.
Secondary Memory: We use secondary memory to store data permanently; it provides space to save data. It is also known as auxiliary memory or external memory. There are various types of data storage devices that help us to save data like Hard disks, CDs, DVDs and USB drives. Data stored in these devices can only be used by a computer through its primary memory. The main aim of data storage devices to store data permanently.
Hard disk contains a number of metallic discs called platters that are coated with a magnetic substance on both sides and therefore can store data on both sides. These platters rotate at a very high speed, they are sealed in a case to ensure a long life.
Compact Disc (CD) is a commonly used storage device it comes in various storage capacities and can store up to 700 MB data in it. A CD is mainly of three types:
Compact Disc- Read Only Memory (CD-ROM) is read only CD which comes preloaded with music or data. We can only read the data on it but cannot erase the data or save extra data into it.
Compact Disc-Recordable (CD-R) is a recordable CD in which the data written into it cannot be erased and hence the CD cannot be used for rewriting.
Compact Disc-Rewritable (CD-RW) is a rewritable CD in which data can be written again and again after erasing the stored data. A computer needs a CD-ROM player to run a CD.
Blu-Ray Disc is the latest among the storage discs and is the most superior from all. It has a large storage capacity of 25 GB. We cannot run a blu-ray disc in a CD-ROM player. We need a blu-ray player to play a blu-ray disc.
USB Drive or Flash Drive is a very small and compact storage device that can store huge amount of data. It comes in various storage capacities ranging from 4GB to 32GB, it is used by simply inserting it into a USB port of the computer.
It is also highly durable device and keeps the data safe and secure. You can rewrite data and it any number of times. A USB drive is commonly known as a pen drive or a thumb drive.
