The memory (RAM) is a volatile memory that stores data for short term use.This means that the memory is lost when there is no power. RAM is used by the CPU when the computer is running, to store data that needs to be used very quickly, but it does not stores any data permanently. Meanwhile, the hard drive in the system unit stores all the the software installed on the computer as well as all the data files created and used by the software including any documents that the user created or downloaded. Compared to random access memory (RAM), hard drive is a permanent storage which means when the computer is turned off, the files remain safely stored in the drive and can be used again some other time. The CD/DVD drive reads data that was recorded on the CD/DVD disk. User can also write or copy important data on an empty disk using the CD/DVD drive.
To upgrade the functionality of a computer, expansion cards are used to amplify the ability of the