Assembly addressing mode and syntax

Question

I'm new to Assembly programming, and searched the web for tutorials and ebooks. I have found some confusing information about syntax in assembly language eg in a tutorial I read the following code:

MOV EBX, [MY_TABLE]     ; Effective Address of MY_TABLE in EBX
MOV [EBX], 110          ; MY_TABLE[0] = 110

And in a book I read:

mov ax, [Data] ; normal direct memory addressing of a wor
mov ebx, Data ; ebx = & Data
3 mov ax, [ebx] ; ax = *ebx

So when we MOV a variable enclosed in [] to a register like EBX , what value do we store in the register? The address or the actual value in that memory location?

Answer 1

From the NASM manual :

The rule is simply that any access to the contents of a memory location requires square brackets around the address, and any access to the address of a variable doesn't. So an instruction of the form mov ax,foo will always refer to a compile-time constant, whether it's an EQU or the address of a variable; and to access the contents of the variable bar , you must code mov ax,[bar] .

So

MOV EBX, [MY_TABLE]     ; Effective Address of MY_TABLE in EBX

is wrong: It does not set EBX to an address, but to the value stored at the MY_TABLE address.