bits 64

    SECTION .data
var1:   dd 0x00112233
var2:   dd 0x55667788

    SECTION .text
global _start
_start:
    %include "header.asm.inc"

    ; interactions between memory and registers
    mov     eax, [var1]         ; store content at address `var1` in eax
    mov     eax, var1           ; store address `var1` in eax
    mov     [var1], eax         ; store eax at address `var1`
    ;mov     var1, eax          ; invalid!

    ; many more instructions allow to work on operands
    add     eax, [var1]         ; add value at address `var1` to eax
    add     [var1], dword 0x42  ; store immediate value at address `var1`

    ; some combinations are invalid, e.g., two memory operands in arithmetic ops
    ; (but many others, too!)
;   add     [var1], [var2]      ; invalid!

    %include "sysexit.asm.inc"