RISC (Reduced Instruction Set Computer) and CISC (Complex Instruction Set Computer) are two primary architectural approaches used in computer processors. They differ significantly in their design philosophies and performance characteristics. ARM (like Apple M series and Qualcomm Snapdragon) adopts a RISC (Reduced Instruction Set Computing) philosophy, whereas x86 (like Intel and AMD) is based on a CISC (Complex Instruction Set Computing) approach. These divergent strategies influence the efficiency and performance of processors and their application in various computing environments.
RISC Architecture
Emphasis on software: RISC relies heavily on software optimization to achieve high performance.
Simple instruction set: A limited number of simple, fixed-length instructions.
Single-cycle execution: Most instructions can be executed in a single clock cycle.
Large number of registers: More registers reduce memory access and improve performance.
Load-store architecture: Memory access is limited to load and store instructions.
Pipelining: Efficient instruction execution through overlapping stages.
ARM (Advanced RISC Machines) brands: Apple M series and Qualcomm Snapdragon.
CISC Architecture
Emphasis on hardware: CISC relies on complex hardware to execute complex instructions.
Complex instruction set: A large number of complex, variable-length instructions.
Multiple-cycle execution: Many instructions require multiple clock cycles to complete.
Smaller number of registers: Fewer registers compared to RISC.
Memory-to-memory architecture: Instructions can directly access memory.
Microcode: Complex instructions are broken down into simpler microcode instructions.
x86 (Advanded SISC Machines) brands: Intel and AMD
Key Differences
| Feature | RISC (ARM) | CISC (x86) |
| Instruction set | Simple, fixed-length | Complex, variable-length |
| Instruction execution | Single-cycle | Multiple-cycle |
| Number of registers | Large | Small |
| Memory access | Load-store | Memory-to-memory |
| Hardware complexity | Simpler | More complex |
| Software complexity | More complex | Simpler |
Choose the right software
If you download a software program beware to always download the right version. Software developers now a day make different versions based on wich operating system you use to wich hardware you use like a x86 (CISC) based cpu or a ARM (RISC) bades cpu and you have also 32 bit vs. 64 bit versions.
More about the diference between ARM and x86 based cpu's (advantages and disadvantages). (link van maken naar)
Which is Better?
The choice between RISC and CISC depends on various factors, including the specific application, power consumption and cost constraints. In general, RISC architectures are more suitable for high-performance computing and embedded systems, while CISC architectures are often used in general-purpose computers.
In recent years, RISC architectures have gained significant popularity due to their simplicity, efficiency and scalability. Apple's Operationg Systems are now fully ARM based and even Microsoft has now a Windows Operating Systems optimised for ARM based CPU's like the Qualcomm Snapdragon for laptops. However, CISC architectures still have a place in certain niche applications like older computer programs. There is also a historical aspect. Since Intel released the x86 architectrue in 1978 it was the only standard until recent years but it will still continue for decades. While ARM historically lagging in raw performance compared to x86, modern ARM processors have significantly closed the gap, especially in multi-core performance and specific applications like AI. ARM based CPU's consume also less energy and are therefore ideal for mobile applications such as smartphones and laptops.
Disadvantage using ARM based CPU's in laptops
Some hughe disadvantage when using an ARM based CPU in laptops is that x86 orientated software will not natively work on ARM based CPU's in the best possible way there will be some sort of software layer that can converts the CISC instructions to RISC instructions so the ARM based CPU will be able to calculate the instructions. But there will be some latency do to the conversion between the two and in many cased software won't simply work at all. Dispite the lower energy consumption and low heat generation they are not yet very suitable for Windows based laptops. The world has to put tremendous lot more work into creating and adapting their software to work natively on ARM based CPU's to be succesfull in the Laptop and Desktop bussiness. Only than this architecture will gain more popularity by the masses and hopefully they will see the potentials of a longer battery life and lower pricing costs.
More about the diference between ARM and x86 based cpu's (advantages and disadvantages).
More information about the difference between SISC and RISC on
https://www.geeksforgeeks.org/computer-organization-risc-and-cisc/
https://cs.stanford.edu/people/eroberts/courses/soco/projects/risc/risccisc/
