We saw that use of a number system with smaller base often requires more positions to represent a given value (recall the reason for using octal and hexadecimal notations) Here four positions are required instead of one to represent decimal number 9 in binary form. In spite of this, almost all computers use binary numbers. Hence, the obvious question is 'Why are binary numbers used instead od decimal numbers?' The reasons are as follows:-
Information is handled by computer's electronic/electrical components such as transistors, semiconductors, wires, etc., and all these can indicate only two states or conditions- ON (state 1) or OFF (state 0). Transistors are either conducting (state 1 ) or non-conducting (state 0), magnetic materials are either magnetized (state 1 ) in one or opposite direction or non-magnetized (state 0), a pulse or voltage is present (state 1) or absent (state 0) in wire. Information is represented within a computer by the presence or absence of these types of signals. Binary number system having only two digits (0 and 1) is most suitable for expressing the two possible states. illustrates the concept of binary components.
By using binary numbers, computer circuits only have to handle two binary digits rather than ten decimal digits. This greatly simplifies the internal circuit design of computers resulting in less expensive and more reliable circuits.
Finally, all possible operations in decimal number system are also possible in binary number system.