In the previous lectures, we already learned about the CPU structure. In this post, I will post the concept of CISC and RISC. In addition, I will mention about the difference with CISC and RISC.
CISC vs RISC
In the early version of computer adopted CISC. However, these days, we use the RISC computer architecture.
CISC -> Complex Instruction Set Computer
RISC -> Reduced Instruction Set Computer
CISC
The goal of CISC is that make every machine instruction for each High-level language.
By doing so, we can match all codes to our machine instruction. In addition, we can simplify the computation and improve the computer performance.
This is the major characteristics for CISC.
I think the most important point is number 3. CISC has variable-length instruction formats. It means that there are many instructions and they have differnet size of memory. It causes the computer architecture more difficulty and expensively.
RISC
This is the summary of RISC structure. This structure has few instruction formats and addressing mode. In addition, we cannot access the memory except for LOAD & STORE Instruction.
It looks simple and easy. So, we might think it is more slower than CISC architecture. RISC architecture has few structure so, we can keep the expression of Simple is best.
Also, they use same size of instruction. So, it will cause improving the performance.
