Cisc vs. Risc
MEMIJE, CHEENEE B. CPE 501
CISC VS. RISC
- Which one is better? -
RISC vs CISC is a topic quite popular on the Net. Everytime Intel (CISC) or Apple (RISC) introduces a new CPU, the topic pops up again. But what are CISC and RISC exactly, and is one of them really better?
This article tries to explain in simple terms what RISC and CISC are and what the future might bring for the both of them. This article is by no means intended as an article pro-RISC or pro-CISC. You draw your own conclusions …
CISC
Pronounced sisk, and stands for Complex Instruction Set Computer. Most PC's use CPU based on this architecture. For instance Intel and AMD CPU's are based on CISC architectures.
Typically CISC chips have a large amount of different and complex instructions. The philosophy behind it is that hardware is always faster than software, therefore one should make a powerful instructionset, which provides programmers with assembly instructions to do a lot with short programs.
In common CISC chips are relatively slow (compared to RISC chips) per instruction, but use little (less than RISC) instructions.
RISC
Pronounced risk, and stands for Reduced Instruction Set Computer. RISC chips evolved around the mid-1980 as a reaction at CISC chips. The philosophy behind it is that almost no one uses complex assembly language instructions as used by CISC, and people mostly use compilers which never use complex instructions. Apple for instance uses RISC chips.
Therefore fewer, simpler and faster instructions would be better, than the large, complex and slower CISC instructions. However, more instructions are needed to accomplish a task.
An other advantage of RISC is that - in theory - because of the more simple instructions, RISC chips require fewer transistors, which makes them easier to design and cheaper to produce.
Finally, it's easier to write powerful optimised compilers, since fewer instructions
CISC VS. RISC
- Which one is better? -
RISC vs CISC is a topic quite popular on the Net. Everytime Intel (CISC) or Apple (RISC) introduces a new CPU, the topic pops up again. But what are CISC and RISC exactly, and is one of them really better?
This article tries to explain in simple terms what RISC and CISC are and what the future might bring for the both of them. This article is by no means intended as an article pro-RISC or pro-CISC. You draw your own conclusions …
CISC
Pronounced sisk, and stands for Complex Instruction Set Computer. Most PC's use CPU based on this architecture. For instance Intel and AMD CPU's are based on CISC architectures.
Typically CISC chips have a large amount of different and complex instructions. The philosophy behind it is that hardware is always faster than software, therefore one should make a powerful instructionset, which provides programmers with assembly instructions to do a lot with short programs.
In common CISC chips are relatively slow (compared to RISC chips) per instruction, but use little (less than RISC) instructions.
RISC
Pronounced risk, and stands for Reduced Instruction Set Computer. RISC chips evolved around the mid-1980 as a reaction at CISC chips. The philosophy behind it is that almost no one uses complex assembly language instructions as used by CISC, and people mostly use compilers which never use complex instructions. Apple for instance uses RISC chips.
Therefore fewer, simpler and faster instructions would be better, than the large, complex and slower CISC instructions. However, more instructions are needed to accomplish a task.
An other advantage of RISC is that - in theory - because of the more simple instructions, RISC chips require fewer transistors, which makes them easier to design and cheaper to produce.
Finally, it's easier to write powerful optimised compilers, since fewer instructions