Computer Architecture, Instruction Set, Intel, X86, Computer Science.
Optional ModR/M format The main purpose of the ModR/M byte is to specify the memory locations that need to be accessed to get the data required for the operation. The byte contains 3 subdivisions. Mod – 2 bits long. Reg/ Opcode – The bits 3, 4, 5 specify a register as an operand or as an opcode