1. Application Of Serial Data Transmission
2. Serial Vs Parallel Communication Explained

The key difference between Serial and Parallel Communication is that in serial communication data transmission occurs bit by bit at a time while in parallel communication multiple bits transmit at a time. However, though the data is transmitted bit by bit, serial communication is fast for long distances and high frequencies. But, parallel communication is fast for short distances and low frequencies but slower for long distances and high frequencies.

At least Two Devices ready to communicate. • A Transmission Medium. • A set of Rules & Procedure for proper communication (Protocol). • Standard Data Representation. • Transmission of bits either Serial or Parallel. • Bit synchronisation using Start/stop bits in case of Asynchronous Transmission. • In Synchronous. Parallel communication is the process of sending/receiving multiple data bits at a time through parallel channels. It is like you are firing using a shotgun to a target – where multiple bullets are fired from the same gun at a time! Serial vs Parallel Communication.

In data communication, the data travels from the source device or sender to the destination device or the receiver. There are multiple devices connected to share data. Serial and parallel communication are two ways of transmitting data from the sender to receiver.

CONTENTS

1. Overview and Key Difference
2. What is Serial Communication
3. What is Parallel Communication
4. Side by Side Comparison – Serial and Parallel Communication in Tabular Form
5. Summary

What is Serial Communication?

In serial communication, there is a single channel between the sender and receiver. In this method, the bits line up at the receiver, and each bit travels through the channel one at a time.

Even though, it appears that serial communication is slower because of transferring one bit at a time, in practice it is fast. The data transmission speed is higher especially at high frequencies and when there are long distances. Furthermore, as there is only one channel or a line, the cost of this communication is minimum. In brief, serial communication is simple, straightforward and accurate.

What is Parallel Communication?

In parallel communication, multiple bits sent through the channels or buses simultaneously. Assume that there are three bits to transmit. Then, they will go through three separate lines from sender to receiver.

For short distances and low frequencies, the parallel communication is fast because several bits transmit at a time. However, when increasing the distance and the frequency, it causes some issues in parallel communication. One major issue is crosstalk. It is the possibility of bits skipping into other channels or buses. This can result in making the output at receiver end different from the sender’s. Another issue is skewing. In other words, the receiver has to wait till the slowest bit arrives. Therefore, even though parallel communication is faster for short distances and low frequencies, the speed gets lower for long distances and high frequencies due to the above issues. In brief, this communication is unreliable and is a complicated transmission method.

What is the Difference Between Serial and Parallel Communication?

Summary – Serial vs Parallel Communication

Both serial and parallel communication are two types of data transmission. The difference between Serial and Parallel Communication is that in serial communication, the data transmission occurs bit by bit at a time while in parallel communication, it is multiple bits transmission.

Reference:

IGCSE Computer Science – Serial and Parallel Data Transfer, James Waring, 11 Dec. 2016. Available here
2.Wikipedia, Wikimedia Foundation, 15 May 2018. Available here

Image Courtesy:

1.’1172193′ by eak_kkk (CC0) via Pixabay

In data transmission, parallel communication is a method of conveying multiple binary digits (bits) simultaneously. It contrasts with serial communication, which conveys only a single bit at a time; this distinction is one way of characterizing a communications link.

The basic difference between a parallel and a serial communication channel is the number of electrical conductors used at the physical layer to convey bits. Parallel communication implies more than one such conductor. For example, an 8-bit parallel channel will convey eight bits (or a byte) simultaneously, whereas a serial channel would convey those same bits sequentially, one at a time. If both channels operated at the same clock speed, the parallel channel would be eight times faster. A parallel channel may have additional conductors for other signals, such as a clock signal to pace the flow of data, a signal to control the direction of data flow, and handshaking signals.

Parallel communication is and always has been widely used within integrated circuits, in peripheral buses, and in memory devices such as RAM. Computer system buses, on the other hand, have evolved over time: parallel communication was commonly used in earlier system buses, whereas serial communications are prevalent in modern computers.

Examples of parallel communication systems[edit]

• IBM System/360Direct Control Feature (1964).^[1]:p.18 Standard System/360 had an eight-bit wide port. The process-control variant Model 44 had a 32-bit width.
• Computer peripheral buses: ISA, ATA, SCSI, PCI and Front side bus, and the once-ubiquitous IEEE-1284 / Centronics'printer port'
• Laboratory Instrumentation bus IEEE-488
• (see more examples at computer bus)

Comparison with serial links[edit]

Before the development of high-speed serial technologies, the choice of parallel links over serial links was driven by these factors:

• Speed: Superficially, the speed of a parallel data link is equal to the number of bits sent at one time times the bit rate of each individual path; doubling the number of bits sent at once doubles the data rate. In practice, clock skew reduces the speed of every link to the slowest of all of the links.
• Cable length: Crosstalk creates interference between the parallel lines, and the effect worsens with the length of the communication link. This places an upper limit on the length of a parallel data connection that is usually shorter than a serial connection.
• Complexity: Parallel data links are easily implemented in hardware, making them a logical choice. Creating a parallel port in a computer system is relatively simple, requiring only a latch to copy data onto a data bus. In contrast, most serial communication must first be converted back into parallel form by a universal asynchronous receiver/transmitter (UART) before they may be directly connected to a data bus.

The decreasing cost and better performance of integrated circuits has led to serial links being used in favor of parallel links; for example, IEEE 1284 printer ports vs. USB, Parallel ATA vs. Serial ATA, and FireWire or Thunderbolt are now the most common connectors for transferring data from AV(audiovisual) devices such as digital cameras or professional-grade scanners that used to require purchasing a SCSI HBA years ago.

One huge advantage of having fewer wires/pins in a serial cable is the significant reduction in the size, the complexity of the connectors, and the associated costs. Designers of devices such as smartphones benefit from the development of connectors/ports that are small, durable, and still provide adequate performance.

On the other hand, there has been a resurgence of parallel data links in RF communication. Rather than transmitting one bit at a time (as in Morse code and BPSK), well-known techniques such as PSM, PAM, and Multiple-input multiple-output communication send a few bits in parallel. (Each such group of bits is called a 'symbol'). Such techniques can be extended to send an entire byte at once (256-QAM).

See also[edit]

Application Of Serial Data Transmission

References[edit]

1. ^IBM Corporation. IBM System/360 Principles of Operation(PDF).

Serial Vs Parallel Communication Explained

• This article incorporates public domain material from the General Services Administration document 'Federal Standard 1037C' (in support of MIL-STD-188).