Thanks folks.

I think I have got the required information to proceed at this stage of design. Foolowing is the summary :

1. If at all using the control lines stick to the basic four and avoid the Secondary ones ( Thanks Prahlad , Russell )

2. Think more on the modality of using the control lines. And easy would be to intiate the required control with specific ASCII codes ( Thanks Abhishek and Andy - this really was an eye opener.)

Raj, I am yet to look at the link posted by you. I am currently in Vizag and on a dial up network - even to read your postings I had to knock off the images - it is that slow here. Will do shortly. Thanks.

And not to forget Ijaz and Erik for your inputs. Thanks guys.

Raghu