what is interrupt?

An interrupt is special signal which sent to the CPU to perform on it by the software and hardware. 

The processor respond by the suspending it's current activities, saving its state and executing a small program called an interrupt handle(or interrupt service routine, ISR) to deal with the event. 

This interruption is temporary, after the interrupt handler finishes, the processor resumes execution of the previous thread. 

Interrupt are basically two types-:

1-: External Interrupt

2-: Internal  Interrupt

what is DMA & DMA controller? How it works?

DMA(Direct Memory Access) -

The  transfer of data between a fast storage device such as magnetic disk and memory is often limited by the speed of the CPU . Removing the CPU from the path and letting all the periferal devices manage the memory buses directly would improve the speed of transfer. This transfer technique is called DMA.

During DMA transfer, the CPU is idle and has no control of the memory buses. 

DMA controller- The DMA controller needs the usual circuits

DMA has many function as follows-:

 BR- Bus Request

BG- Bus grant

BT- Burst transfer

CS- cycle stealing

Bus request- CPU that facilitate the DMA                            transfer . 

What is synchronous data transfer?

Synchronous data transfer-:
      Sender and receiver use the same clock signal

1) - support high data transfer rate.
2) - needs clock signal between the                   sender  and the receiver
3) -  requires master/slave configuration

what is inheritance?

An object can reuse the properties of other objects which belong to another class. It is known as inheritance. With inheritance we can reuse an existing class to build a new class. A new class or sub class shares common properties with the class from which it derived. A existing class is known as parent class and a new class is known as derived class. 

When a class inherits from one parent class is known as single inheritance but when derived class have more parent class it is called multiple inheritance. 

what is polymorphism?

Polymorphism means that some of the functions perform their action differently  in different classes. It is very unique and powerful concept to revise something without changing it. Such as class 'shape' have sub classes circle, triangle etc and 'draw () ' is a method of 'shape'  class which is shared by all the sub classes at 'shape'.