Introduction
Q: How do we relay encoded data from the generating device to the next device?A: Interface
- Defined by several popular standards
- Physical layer of the OSI model
- Mechanical/electrical/functional specifications
Digital Data Transmission
Do we send one bit at a time or do we group bits into larger groups and if so, How?
Parallel Transmission
- Binary data consisting of 1s and 0s may be organized into groups of ‘n’ bits each
- By grouping we can send data ‘n’ bits at a time instead of one bit
Serial Transmission
- One bit follows another, so we need only one channel rather than ‘n’ to transmit data between two devices
- Conversion devices are required at the interface
Advantage
- COST
Types of Serial Transmission
There are two types of Serial Transmission:- Asychronous Transmission
- Synchronous Transmission
Asynchronous Transmission
- It is so named because the timing of the signal is unimportant. Instead information is received and translated by agreed upon patterns
- Start and Stop Bits
Asynchronous Transmission
Advantages
- Cheap
- Effective
Disadvantages
- Slow
Synchronous Transmission
Data is transmitted as an unbroken string of 1’s and 0’s and the receiver separates that string into the bytes or characters it need to reconstruct the information
Synchronous Transmission
Advantage
- Speed
Summary
Introduction to Interfaces- Digitl Data Transmission
- Parallel Transmission
- Serial Transmission
- Asynchronous Transmission
- Synchronous Transmission
Reading Sections
- Section 6.1,6.2, “Data Communications and Networking” 4th Edition by Behrouz A. Forouzan