When do you use the 82C55 parallel interface chip?

[i.mehrzad]

I have a basic doubt about the usage pf 82C55.

Wanted to know when exactly it is used. Eg: For a keyboard you have to use a 82C55 but for a LCD it is not necessary. So when exactly do we use it??

 

[berkeman]

I have a basic doubt about the usage pf 82C55.

Wanted to know when exactly it is used. Eg: For a keyboard you have to use a 82C55 but for a LCD it is not necessary. So when exactly do we use it??

Can you give us some links to application notes for that PPI part? What are your thoughts on when and why it is used?