8086 op-code need help

Discussion in 'General Electronics Chat' started by ericyeoh, Aug 15, 2011.

  1. ericyeoh

    Thread Starter Active Member

    Aug 2, 2009
    Hi guys, just wanna ask for confirmation on below op-code.

    ADD Bx,1234.

    "ADD immed to reg/mem 100000sw mod000r/m [addr] data"

    then 1000 0001[SW] 11[mod] 011[BX] 110 [direct address]

    opcode = 81 DE H

    Is is correct?

    How about MOV [1234],AX?
  2. wade99

    New Member

    Aug 16, 2011
    It has been a while since I used 8086, but here goes.
    Your explanation looks right.

    MOV [1234],AX means that the value in AX will be moved to the memory address 1234.

    Do you have a method of single stepping your code. I used a program SYMDEB years ago which would show you what you are asking about.