32/64-Bit 80x86 Assembly Language Architecture

Appendix C. Reg/Mem Mapping

This appendix maps the addressing methods for memory load/save, jump table lookup, and call table lookup.

The same kind of memory reference that is used to access a memory table or array can also be used to access a jump vector. Almost any register can be used alone, in a pair addition, and with an optional base address and/or scale factor of {2, 4, or 8}, but you will note that there are some limitations in regard to the ESP register.

(Real Mode — Near or far is same opcodes)(Protected Mode — Near or far is same opcodes)

  jmp . . .
  jmp NearAdrPtr[. . .]

eax	ebx	ecx	edx	esp	ebp	esi	edi
ax	bx	cx	dx	sp	bp	si	di

(Real Mode — Near or far is same opcodes)(Protected Mode — Near or far is same opcodes)

 jmp word ptr [. . .] jmp dword ptr [. . ...