Free Trial

Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.

  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint

14.1. Introduction

Data communication has been around since the birth of telegraphy, way before any computers arrived on the scene. Early telegraphy primarily used Morse code to send text messages. Because this type of communication had to go hundreds and thousands of miles via a copper medium utilizing the then novel invention of electricity, it was deemed to be more economic to send a signal (coded as a series of short and long pulses) in a serial manner on a pair of wires. The use of the Morse code eventually became standardized, thus signaling the beginning of serial signal engineering.

Serial signaling has evolved to support computer-to-computer communications including Ethernet (and its various siblings). For electronic systems that are closer in proximity to each other, such as between boards or between components, designers may take liberty to use more wires or printed-circuit board (PCB) traces. At this level of communication, it is advantageous to use a less complex signaling scheme at the cost of more wires/board space. The term “bus” was invented. This essentially describes the communication pictorially: a set of data gets on a bus together and travels along together. Upon reaching a destination, they may depart together or continue onto the next stop. The bus can also pick up new data from any bus stop (agent) as long as a simple protocol is followed. A parallel bus is a common communication method, especially for component-to-component (on a board) and between board-to-board in close proximity.


  

You are currently reading a PREVIEW of this book.

                                                                                                                    

Get instant access to over $1 million worth of books and videos.

  

Start a Free Trial


  
  • Safari Books Online
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint