DEMULTIPLEXER

A demultiplexer, also known as a demux, is a device that takes a single input and routes it to one of several possible output lines. It is the opposite of a multiplexer, which takes multiple inputs and combines them into a single output.

Serial data refers to data that is transmitted or received one bit at a time, while parallel data refers to data that is transmitted or received multiple bits at a time. In the context of this question, a device that changes from serial data to parallel data means that it takes a serial input and converts it into parallel output.

The correct answer is option 'A' - DEMULTIPLEXER - because a demultiplexer is specifically designed to perform this function. It has a single input line and multiple output lines, and it selects one of the output lines based on the control inputs.

Here is a detailed explanation of how a demultiplexer works and how it converts serial data to parallel data:

1. How a demultiplexer works:
- A demultiplexer has one input line and several output lines, which are typically represented as Y0, Y1, Y2, etc.
- The number of output lines is determined by the number of control inputs, which are used to select the desired output line.
- The control inputs are binary inputs, and the number of control inputs determines the number of possible output lines (2^n, where n is the number of control inputs).
- The demultiplexer uses the control inputs to route the input data to the selected output line.
- When a particular combination of control inputs is applied, the corresponding output line is activated and carries the input data.

2. Conversion from serial to parallel data:
- In the context of this question, the input data is in serial form, meaning that it is transmitted or received one bit at a time.
- The demultiplexer takes this serial input and uses its control inputs to select the desired output line.
- Each output line carries one bit of the input data, which is why it is referred to as parallel data.
- By selecting the appropriate output line, the demultiplexer can convert the serial data into parallel data.

In conclusion, a device that changes from serial data to parallel data is a demultiplexer. It takes a single input (serial data) and routes it to one of several output lines (parallel data) based on the control inputs.