Portability of machine language: Is machine language (binary opcodes) independent of the microprocessor type, or is it architecture-specific and therefore not portable across different CPUs?

Introduction / Context:
Machine language is the lowest-level programming representation: the exact bit patterns that a CPU decodes into actions. Whether those bit patterns are portable across different processors is a critical concept for cross-platform development and binary compatibility.

Given Data / Assumptions:

• Different microprocessor families define different Instruction Set Architectures (ISAs).
• Opcodes, encodings, and calling conventions vary significantly by ISA.
• Endianness and operating systems are additional—but separate—considerations.

Concept / Approach:
Machine language is inherently architecture-specific. A binary compiled for one ISA (e.g., ARM, x86, RISC-V) is not understood by a different ISA because the opcode encodings and instruction semantics differ. Portability is achieved by recompiling source code for the target ISA or by using emulation/translation layers, not by reusing the same machine code bits.

Step-by-Step Solution:

Verification / Alternative check:
Attempting to execute x86 binaries on ARM without translation fails; cross-compilation produces new machine code tailored to the target ISA. This confirms architecture dependence.

Why Other Options Are Wrong:
RISC vs CISC is irrelevant to the portability fact. Recompilation changes the machine code, not its independence. Endianness alone does not harmonize different opcodes.

Common Pitfalls:
Confusing portability of high-level source with portability of binaries; assuming shared endianness or OS ABI implies instruction compatibility.

Final Answer:
Incorrect