Populate a cell from another cell allowing both a formula and the cell to be edited

Hi Guys

Is it possible to populate a cell from another cell allowing both a formula and the cell to be edited?

e.g

IF(A1 = "No", B1 = "N", "Y".

This would allow B1 to be populate by whatever was in A1 and B1 would also be editable.

Thanks

Hi Special-K

Thanks for the reply. I understand that. However, what I am trying to do is allow a YES/NO on a dropdown list to populate a whole column on a different sheet with a Y or N to begin. After this I will allow each individual cell to be overwritten.
I want the column to literally have a Y or N but not a formula. Hence the reason I want to populate it from another column and not write a formula directly into the column itself.

I'm not the best at explaining, hope you understand.

Any help would be appreciated

Andrew