Question

1. Suppose content of a byte is AC in hexadecimal.

A) Write it down as an 8 bit sequence.

(b) What is the basic motivation to have a DMA?

Answer 1

A)  As the content of a byte in hexadecimal and one hexadecimal contains 4-bit.

Then, the bit sequence of 'AC' is -

Here, A has value 10 and have bit value '1010' and

B has a value 11 and have bit value '1011'.

So, the 8-bit sequence of AC is (10101011).

B) ​​​​​ Basic motivation to have DMA :-

The basic motivation to have DMA is that computer systems use a DMA controller which is an intermediate device that handles the memory transfer, allowing the CPU to do other things.

DMA mode of data transfer is faster amongst all the mode of data transfer . It transfers data from one memory to another without CPU interruption as it improves system performance by allowing external devices to transfer information directly to or from the PC's memory without using the CPU. The process is managed by a chip known as a DMA controller.

With DMA, the CPU first initiates the transfer, then it does other operations while the transfer is in progress, and it finally receives an interrupt from the DMA controller (DMAC) when the operation is done.

So, the motivation to have DMA is it makes processor free to do other task it manages memory transfers.

Thumps up!