Assembly, the meaning behind the colon ":"

Question

I am new to assembly, and now I am reading a manual that often comes up with things like ax:bx , ds:dx , ss:sp .

I will use one of the above in the example from the book "Mastering a Turbo Unit".

Note that the logical address in ss: sp points to a byte below the last byte on the stack.

What is the meaning of the notation:?

Sincerely.

Answer 1

These are the memory addresses expressed in the segment diagram: offset. See http://thestarman.pcministry.com/asm/debug/Segments.html