Gopal,

I would factor a few things into the decision.

1) Is this a product or a project. Your support and development requirements could be quite different depending on the answer to this question.

2) What are you building? Your device requirement should already dictate a throughput and connectivity requirement. Does this scale to an 8051 platform if memory is excluded from the equation?

3) If the job scales to a '51 how will you use memory? If you fill it linearily (sequential data capture), or post/query binary structures banking works well.

4) I often implement 16 bit periph's that source data into or "peal" data sequentially out of memory. The computational tasks can be very simple in which case i build simple DMA for a 16 bit memory array to which the periph's connect directly. The 8051 banks into either 8 bit rank and does it's simple task.
5) Think hard if a 16 bit solution is required you will save a lot of time just comitting to the right device.

regards,
p

use fairly good size memories often and find ban