Notes-Computer Architecture


Number system and it’s types

1. Decimal number system:-
A system based on decimal digits (0,1,2,3,4,5,6,7,8,9).Decimal system have radix or base 10 which means that each digit in the number is multiplied by 10 raised to power corresponding to that digit position.
Example:-
86=8×10+6×1

2. Binary number system:-
It has two symbols or possible digit values 0 and 1.It has radix or base 2 which can be used to represent any quantity that can be represented in decimal or other number system.
Example:-
1101

3. Octal number system:-
It has base 8 ,meaning 8 unique symbols which are 0,1,2,3,4,5,6,7.Thus,each digit can have any value from 0 to 7.
Example:-
3704.1305

4. Hexadecimal number system:-
It uses radix or base 16.It has 16 possible digit symbols.It uses digits 0 to 9 and the letter A, B ,C ,D, E, F.
Example:-
CF5A

Sequential Circuits

These are logic circuits whose present output depends on past inputs.It stores and remember information.It is time dependent.It is a connection of flip flops and gates.Two types are-

¤Synchronous-It uses flip flops and its status can change only at discrete instants.

¤Asynchronous-It can be regarded as combinational circuits with feedback path.

Combinational Circuits

These are interconnected circuits of gates according to certain value to produce an output depending on its value.It should not have feedback loops.It can be represented as a network of gates.It can be expressed by a truth table or a Boolean expression.It is independent of time.