• More about CISC and RISC architectures and instruction sets..

    From World90@21:1/5 to All on Sat Nov 21 15:45:32 2020

    More about CISC and RISC architectures and instruction sets..

    Read here:


    It says the following:

    Disadvantages Of RISC:

    - Designing compiler using RISC is complicated.

    This is what i don't like in RISC instruction set, it pushes the
    complexity towards the software compilers, also the RISC compilers must implement instruction scheduling algorithms such as to take advantage of parallelism in instruction processing and if this is poorly handled,
    than the RISC machine's performance will directly be impaired. And x86 instruction set is much richer than RISC instruction set, so i think
    that it is much more higher level , so i think that it permits a higher
    level programming that is safer, since i think that the x86 hardware of
    the x86 instruction set was stabilized and is in my opinion much safer
    than the RISC approach. This is why i don't like ARM or RISC-V because
    they push the complexity towards the compiler side and i think that it
    is less safe than the CISC approach.

    Read my following previous thoughts:

    What about x86 vs ARM processors ?

    x86 instruction set is CISC and x86 architecture is RISC(inside)
    and ARM instruction set is RISC and ARM architecture is RISC.

    The CISC approach attempts to minimize the number of instructions per
    program, sacrificing the number of cycles per instruction. RISC does the opposite, reducing the cycles per instruction at the cost of the number
    of instructions per program.

    The RISC ISA emphasizes software over hardware. The RISC instruction set requires one to write more efficient software (e.g., compilers or code)
    with fewer instructions. CISC ISAs use more transistors in the hardware
    to implement more instructions and more complex instructions as well.

    CISC simplify the software by needing hardware structure to be more complex.

    Programming CISC-based computers is easier than in other designs because
    there is a single instruction for both simple and complex tasks.

    Programming in RISC is more difficult and time-consuming than in the
    other design, because most of the complex instructions are simulated
    using simple instructions.

    So i think that CISC instruction set is less error prone to program than
    RISC instruction set, so i think that x86 instruction set is better
    for safety.

    Thank you,
    Amine Moulay Ramdane.

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