BTR               Bit Test and Reset (386)           Flags: O D I T S Z A P C
                                                                            *
BTR destination, source

           Logic:          CF . bit, bit . 0

     The Bit Test instructions manipulate individual bits. The source
     operand specifies the bit position in the destination operand. BTR
     copies that bit to the carry flag, and then resets it (sets it to 0) in
     destination.

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   Operands                    Clocks  Transfers  Bytes  Example
   BTR register, immediate8    6  (386)    -        3    BTR AX,3
   BTR memory, immediate8      8  (386)    -        3    BTR MEMLOC,3
   BTR register, register      6  (386)    -        3    BTR AX,BX
   BTR memory, register        13 (386)    -        3    BTR MEMLOC,AX
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        Note:          Both memory and register operands can be either
                       16 bits or 32 bits.