GNU Info

(nasm.info)Section B.4.156

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B.4.156. `MOV': Move Data
-------------------------

     MOV r/m8,reg8                 ; 88 /r                [8086]
     MOV r/m16,reg16               ; o16 89 /r            [8086]
     MOV r/m32,reg32               ; o32 89 /r            [386]
     MOV reg8,r/m8                 ; 8A /r                [8086]
     MOV reg16,r/m16               ; o16 8B /r            [8086]
     MOV reg32,r/m32               ; o32 8B /r            [386]

     MOV reg8,imm8                 ; B0+r ib              [8086]
     MOV reg16,imm16               ; o16 B8+r iw          [8086]
     MOV reg32,imm32               ; o32 B8+r id          [386]
     MOV r/m8,imm8                 ; C6 /0 ib             [8086]
     MOV r/m16,imm16               ; o16 C7 /0 iw         [8086]
     MOV r/m32,imm32               ; o32 C7 /0 id         [386]

     MOV AL,memoffs8               ; A0 ow/od             [8086]
     MOV AX,memoffs16              ; o16 A1 ow/od         [8086]
     MOV EAX,memoffs32             ; o32 A1 ow/od         [386]
     MOV memoffs8,AL               ; A2 ow/od             [8086]
     MOV memoffs16,AX              ; o16 A3 ow/od         [8086]
     MOV memoffs32,EAX             ; o32 A3 ow/od         [386]

     MOV r/m16,segreg              ; o16 8C /r            [8086]
     MOV r/m32,segreg              ; o32 8C /r            [386]
     MOV segreg,r/m16              ; o16 8E /r            [8086]
     MOV segreg,r/m32              ; o32 8E /r            [386]

     MOV reg32,CR0/2/3/4           ; 0F 20 /r             [386]
     MOV reg32,DR0/1/2/3/6/7       ; 0F 21 /r             [386]
     MOV reg32,TR3/4/5/6/7         ; 0F 24 /r             [386]
     MOV CR0/2/3/4,reg32           ; 0F 22 /r             [386]
     MOV DR0/1/2/3/6/7,reg32       ; 0F 23 /r             [386]
     MOV TR3/4/5/6/7,reg32         ; 0F 26 /r             [386]

   `MOV' copies the contents of its source (second) operand into its
destination (first) operand.

   In all forms of the `MOV' instruction, the two operands are the same
size, except for moving between a segment register and an `r/m32'
operand. These instructions are treated exactly like the corresponding
16- bit equivalent (so that, for example, `MOV DS,EAX' functions
identically to `MOV DS,AX' but saves a prefix when in 32-bit mode),
except that when a segment register is moved into a 32-bit destination,
the top two bytes of the result are undefined.

   `MOV' may not use `CS' as a destination.

   `CR4' is only a supported register on the Pentium and above.

   Test registers are supported on 386/486 processors and on some
non-Intel Pentium class processors.