RCL              Rotate through Carry Left           Flags: O D I T S Z A P C
                                                            *               *
RCL destination,count

                         +---.--------------------+
                     +---+--+  +---------------+  |
                     |  CF  |.-|  Destination  |.-+
                     +------+  +---------------+

    RCL shifts the word or byte at the destination to the left by the
    number of bit positions specified in the second operand, COUNT. A bit
    shifted out of the left (high-order) end of the destination enters the
    carry flag, and the displaced carry flag rotates around to enter the
    vacated right-most bit position of the destination. This "bit
    rotation" continues the number of times specified in COUNT. (Another
    way of looking at this is to consider the carry flag as the highest
    order bit of the word being rotated.)

    If COUNT is not equal to 1, the Overflow flag is undefined. If COUNT
    is equal to 1, then the Overflow Flag is set to the XOR of the top 2
    bits of the original operand.

  --------------------------------------------------------------------------
   Operands                  Clocks   Transfers  Bytes   Example
                           byte(word)
   register, 1                 2          -        2     RCL CX,1
   register, CL            8 + 4/bit      -        2     RCL BL,CL
   memory, 1              15(23) + EA     2       2-4    RCL MULTIPLY_X_2,1
   memory, CL           20(28)+EA+4/bit   2       2-4    RCL MOVE_AROUND,CL
  --------------------------------------------------------------------------

       Note:          COUNT is normally taken as the value in CL. If,
                      however, you wish to rotate only one position,
                      replace the second operand, CL, with the value 1, as
                      shown in the first example above.

                      The 80286 and 80386 microprocessors limit the COUNT
                      value to 31.  If the COUNT is greater than 31, these
                      microprocessors use COUNT MOD 32 to produce a new
                      COUNT between 0 and 31.  This upper bound exists to
                      limit the amount of time that an interrupt response
                      will be delayed waiting for the instruction to
                      complete.

                      Multiple RCLs that use 1 as the COUNT may be faster
                      and require less memory than a single RCL that uses
                      CL for COUNT.

                      The overflow flag is undefined if the rotate count
                      is greater than 1.