Rob:
I know what the 8155 'has'. My point was that something like Philips' P89C668 has much, much more, in a single package!

I appreciate you trying to say what I have been saying, sometimes it comes across better with different words.

Abishek:
its expected you know 8155, its very like you.

what was my point initially, instead using same port multiply better go for more powerful MCUs like you stated. It was the 8085 time where it has to be done via external ciruits. if still want to do with big boards and externals, do it with 8085+(Nx8155).

but some people here who think that they are best designers of the world, and some compile lines like compilers. i think waqar zaka was right.

evidently not

Erik