Software Handshaking

Software handshakin occurs when one device controls another by the content of the data. For example, one way to control a printer is by having the computer send its characters line-by-line. After each line, the computer automatically puts in a character saying to the printer "This is the end-of-line .. I'm waiting for your signal to send the next line". The printer accepts the line, prints it, then sends a character back to the computer, meaning, "I 'm ready for another line". This is an easy way to control a printer, but not all printers are able to recognize or respond to such control characters in the data stream.

Hardware Handshaking

With hardware handshaking we are working at a more fundamental level where a printer can actually force the computer to pause in sending characters just by changing the voltage on a wire. It solves communication problems at the most basic hardware/mechanical level - that is, with wires and voltages instead of with programs and codes. The disadvantage of this kind of handshaking is that it can be used only where devices can be physically connected through a cable. This makes it unsuitable for use with modems.