SUB             Subtract                             Flags: O D I T S Z A P C
                                                            * - - - * * * * *
SUB destination,source

        Logic   destination ← destination - source

    SUB subtracts the source operand from the destination operand and
    stores the result in destination.

    When an immediate byte value is subtracted from a word operand,
    the immediate value is first sign-extended to the size of the
    destination operand.


    Opcode      Format
    28 /r       SUB  r/m8,r8
    29 /r       SUB  r/m16,r16
    29 /r       SUB  r/m32,r32
    2A /r       SUB  r8,r/m8
    2B /r       SUB  r16,r/m16
    2B /r       SUB  r32,r/m32
    2C ib       SUB  AL,imm8
    2D iw       SUB  AX,imm16
    2D id       SUB  EAX,imm32
    80 /5 ib    SUB  r/m8,imm8
    81 /5 iw    SUB  r/m16,imm16
    81 /5 id    SUB  r/m32,imm32
    83 /5 ib    SUB  r/m16,imm8
    83 /5 ib    SUB  r/m32,imm8


    Length and timing
    Operands    Bytes   8088    186     286     386     486     Pentium
    reg, reg     2       3       3       2       2       1       1   UV
    mem, reg  2+d(0,2)  24+EA   10       7       7       3       3   UV
    reg, mem  2+d(0,2)  13+EA   10       7       6       2       2   UV
    reg, imm  2+i(1,2)   4       4       3       2       1       1   UV
    mem, imm  2+d(0,2)  23+EA   16       7       7       3       3   UV*
               +i(1,2)
    acc, imm  1+i(1,2)   4       4       3       2       1       1   UV

       * = not pairable if there is a displacement and immediate