xchg ax,bx    ;exchanges ax with bx

xchg ah,al    ;swap the high and low bytes of ax


;XCHG a register with memory
mov dx,0FFFFh
mov word ptr [ds:userRam],dx
mov si,offset userRam
mov ax,1234h
xchg ax,[si]   ;exchange ax with the value stored at userRam. Now, ax = 0FFFFh and the value stored at userRam = 1234h


;XCHG a register with a value on the stack.
mov ax,1234h
mov bx,4567h
push bx
push bp
mov bp,sp      ;using [sp] as an operand for XCHG will not work. You need to use bp instead.

xchg ax,[2+bp] ;exchanges AX with the value that was pushed from BX onto the stack. Now, AX = 4567h,
               ;and the entry on the stack just underneath the top of the stack is 1234h.