Can someone explain line buffers

[stcogolin]

Hi, I'm a newbie and have built a few circuits interfacing with
the parallel port, basically following other's designs. Can someone
explain to me or indicate where I can find info that explains why
octal line-buffers are necessary for communications with parallel
port and what they exactly do?

 

[Nigel Goodwin]

Hi, I'm a newbie and have built a few circuits interfacing with
the parallel port, basically following other's designs. Can someone
explain to me or indicate where I can find info that explains why
octal line-buffers are necessary for communications with parallel
port and what they exactly do?

They buffer the signals either in or out of the port. A parallel port is often part of the motherboard, so blowing it could be expensive - it's wise to use buffers so you blow the buffers and not the port.

 

[Isotope]

Provides
1. isolation between input and output
2. enough power to drive the buses.