What does OFFSET in 16 bit assembly code mean?

Question

I am going through some example assembly code for 16-bit real mode.

I\'ve come across the lines:

    mov    bx, cs
    mov    ds, bx
    mov    si,          


        

Answer 1

In x86 16bit mode, address space is not flat; instead, addresses are composed of an offset and a "segment". The "segment" points to a 64K space, offset is within that space.

See http://en.wikipedia.org/wiki/Memory_segmentation