Computer data is transmitted on the basis of bits and bytes. In the computer, their communication is through wires. These communication are parallel and sequential.
Parallel Communication
In parallel communication, binary data is organized into groups of bits and organized data is transmitted together, just as we speak as words by organizing letters while speaking. In parallel communication, the wire is used according to the number of bits to send, that is, if 8-bit is to be sent, then 8 wires will be used. In parallel transmission all the bits of each byte are transmitted simultaneously. For ASCII characters we need eight channels. All the bits are transmitted together and reach the destination simultaneously.
The main advantage of parallel communication is speed. That is, data communication is faster than serial communication, but parallel communication is more expensive.
Advantage
- Data can be transmitted at very high speed.
Disadvantages
- As it uses parallel paths, this can lead to cross talk. Therefore, it is not suitable for transferring data over long distances.
- To reduce cross talk, the cable length should be limited. it’s expensive. (Because, there must be a separate channel for each bit)
Serial Communication
In sequential communication, one bit follows the other. Serial communication is cheaper than parallel communication. Serial transmission is the most commonly used method of communication. In the serial transmission of each byte, the bits are transmitted along a single path. Then the receiver assembles the incoming bit stream into characters. In serial transmission, the bits of each byte are sent along a path one after the other. An example is the serial port (RS-232), used for a mouse or MODEM.
There are two types of serial communication-
- Asynchronous Transmission – In asynchronous data communication, the data byte is accompanied by an end and a start bit, the purpose of which is to inform the receiver about the beginning and end of each byte. In this, the data transfer takes place in the form of bytes.
- Synchronous Transmission – In synchronous or synchronous communication, the data is in the form of a frame, which is made up of groups of different bytes, the receiver separates the byte from this frame.
Advantages
- This is a cheap way to transfer data (cheap mode).
- It is suitable for transmitting data over long distances.
Disadvantage
- This method is not efficient but slow as it transfers data in series.
