how to copy/paste data of a range only on empty cells of other equal range.

I have two columns A and B with data on some of their cells, and some other cells are empty, randomly.
I need to paste data of column A over column B but only on empty cells of B (I don’t want to override if there is data on cells of Column B). I mean, i want to paste only if the cell on column B is empty and if not just skip it.
The purpose is to unify data of both columns given the fact that values of column B is preferable than data of columns A (except where cells of column B are empty, better A than nothing)
On Paste Special dialog, I find the option “Skip empty cells”, but I think I need just the opposite: “Skip full cells”.

How can I do this selecting the full range of cells (they are too many to do it manually one by one)?

Hope you understand.
Thanks a lot.

I can only imagine column C formula =IF(B1<>"";B1;A1) and copy column C over B (values/text only), but there may be guys here having a smarter solution

Do it in an opposite way - copy B column over A via Paste Special dialogue with Skip empty cells option checked.

OMG - I’m getting old