Computer storage and digital representation of data
If you are having problems in understanding the basics about the computer storage systems,then this hub is for you.This hub explains in detail the two storage systems of computers;primary and secondary. It then discusses the binary language which is the computer's language.
Computer systems data storage can be divided into :-Primary storage and Secondary storage.
Primary storage is the only storage directly accessible by the CPU. It is volatile in nature meaning it loses the information when the power is interrupted. There are 4 types of memory chips which are:-
- RAM,the random access memory is temporary storage area for containing data and instructions.It is volatile and thus the work should be transferred to the secondary storage on a regular basis.
- ROM,the read only memory has start-up instructions and the user cannot make changes to it without special equipment.
- CMOS,Complementary metal-oxide semiconductor chips are powered by battery and retains its contents as long as the battery has power. These chips can be reprogrammed to a certain degree such as when we make changes to the clock for day time savings etc.
- flash memory chips which are gaining popularity as these chips can be erased and reprogrammed and thus are more expensive than RAM.
The other data storage, the secondary storage is non volatile that is it does not lose its data and instructions when switched off. Its data is transferred to the primary storage before it can be used by the CPU. Common types of secondary storage devices are :-
- Magnetic disk storage is the most common form and is made of metal or plastic. It can store a large amount of data as compared to the magnetic tape.
- Hard disk drives are permanently installed on the computer and can store huge amounts of data as compared to the floppy disk drives which have become outdated and can only store limited data such as 1.44 MB whereas a hard disk can store 10 GB or more data.
- DVDs and CDs are being used commonly as a form for storing data and can store data in huge quantities.
Unlike humans the computer does not understand the English language or any other language. It only understands the binary language. The binary language has only zeros and ones. 0 means off and 1 means on. The smallest amount of data(0 or 1) is called bit.
8 bits = 1 byte which is used to represent characters, numbers or letters.
In computers the characters, letters etc are represented by binary coding schemes which are :-
- American Standard Code for Information Interchange(ASCII).It is mostly used by micro and mini computers.
- Extended Binary Coded Decimal Interchange Code (EBCDIC).It is used by mainframe computers.
- Unicode. This binary code uses 16 bits to represent each character and so it can represent all different character sets in the world.