ADD -- Add

Opcode    Instruction         Clocks    Description

04 ib     ADD AL,imm8          2        Add immediate byte to AL
05 iw     ADD AX,imm16         2        Add immediate word to AX
05 id     ADD EAX,imm32        2        Add immediate dword to EAX
80 /0 ib  ADD r/m8,imm8        2/7      Add immediate byte to r/m byte
81 /0 iw  ADD r/m16,imm16      2/7      Add immediate word to r/m word
81 /0 id  ADD r/m32,imm32      2/7      Add immediate dword to r/m dword
83 /0 ib  ADD r/m16,imm8       2/7      Add sign-extended immediate byte
                                        to r/m word
83 /0 ib  ADD r/m32,imm8       2/7      Add sign-extended immediate byte
                                        to r/m dword
00 /r     ADD r/m8,r8          2/7      Add byte register to r/m byte
01 /r     ADD r/m16,r16        2/7      Add word register to r/m word
01 /r     ADD r/m32,r32        2/7      Add dword register to r/m dword
02 /r     ADD r8,r/m8          2/6      Add r/m byte to byte register
03 /r     ADD r16,r/m16        2/6      Add r/m word to word register
03 /r     ADD r32,r/m32        2/6      Add r/m dword to dword register

Operation

DEST := DEST + SRC;

Description

ADD performs an integer addition of the two operands (DEST and SRC). The result of the addition is assigned to the first operand (DEST), and the flags are set accordingly.

When an immediate byte is added to a word or doubleword operand, the immediate value is sign-extended to the size of the word or doubleword operand.

Flags Affected

OF, SF, ZF, AF, CF, and PF as described in Appendix C

Protected Mode Exceptions

#GP(0) if the result is in a nonwritable segment; #GP(0) for an illegal memory operand effective address in the CS, DS, ES, FS, or GS segments; #SS(0) for an illegal address in the SS segment; #PF(fault-code) for a page fault

Real Address Mode Exceptions

Interrupt 13 if any part of the operand would lie outside of the effective address space from 0 to 0FFFFH

Virtual 8086 Mode Exceptions

Same exceptions as in Real Address Mode; #PF(fault-code) for a page fault

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