What is CPU Architecture ??

1)RISC (Reduced Instruction Set computing) architecture uses a limited number of very powerful instructions.The CPU type requires fewer transistors in the CPU for processing and generally results in faster CPU performance
CISC (Complex Instruction Set Computing) allows any number of instructions to be used in the CPU and the CPU must provide all the internal circutry needed to process each instruction.
CISC CPU's are mostly found in PentiumI-4,or AMD Athlon and DURON
CPU Archieture is the technolgy and techniques to improve performance

I would agree with Answer #1 with the exception of the computer architecture. I include the text from Answer #1 at the end of this message for easier reading.

Computer architecture, in my opinion, is the end result of the design requirements of a computer/product. This would not necessarily mean a product is designed for performance, although most designs probably would take this into consideration, especially in the PC world. Items such as the bus width used (8, 16, 32, 64 bit) for memory and IO, number of memory ports, whether a PCI channel or DMA is included, and the methods of multiplexing/demultiplexing data are items of the CPU architecture. The CPU has this included within its CPU chip and its supporting controllers chips. External featurers such as sound, video, modem and network controllers, floating point units would not be considered part of the CPU architecture, though they would have to adapt or interface to the CPU as specified by the CPU's architectural specifications. External featuers would have their own internal/external architecture.
End of opinion.

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Text from Answer #1
1)RISC (Reduced Instruction Set computing) architecture uses a limited number of very powerful instructions.The CPU type requires fewer transistors in the CPU for processing and generally results in faster CPU performance
CISC (Complex Instruction Set Computing) allows any number of instructions to be used in the CPU and the CPU must provide all the internal circutry needed to process each instruction.
CISC CPU's are mostly found in PentiumI-4,or AMD Athlon and DURON
CPU Archieture is the technolgy and techniques to improve performance

Hi,

Hopefully spelling it out a little clearer and slightly change what soulrider had to say...

RISC, being reduced instruction set means that the instructions aren't in fact powerful - rather thay are very simple. They ARE however easier and smaller to implement in the silicon and so that results in a processor that can run very, very fast. A risk program is typically twice as big as a CISC one as it simply has more instructions.

For example the Digital Equipment Corporation's "Alpha"chip was RISC and achieved 1+Ghz speeds years ago.

CISC on the other hand is unwieldy and complex. But each instruction does a lot. So a slower clock speed results in more real work. PCs use the CISC architecture.

In recent years, Intel and AMD have changed their chip design to include "pipelines". These effectively split up complex instructions into a series of simple steps - making the modern PC's CPU kind of a RISC/CISC hybrid.

Pipelines have problems though and the CPUs and compilers are becoming ever more complex to try to overcome these problems.

I read a great article on Piplining not so long ago so I'll find it and add it to this post.

Cheers,
Tim.

CPU architecture is the layout of the internals of the CPU like how the transisitors and other electronics are laid out. Since in todays CPU's there are over a million transistors on a single wafer of silicon, its not possible for humans to see thearchitecture without some magnifying device.

CPU run on a set of instructions, to perform mathemetical operations like addition, subtraction etc. In plain English it would be somthing like this

Store number A in this register. (place to store values in a CPU)
Store Number B in this register.and so on

In earlier days the number of instruction required a simple operation were plenty. So some vendors brought out CPU's with a reduced set of instructions to perform operations and called the technology Reduced Instruction Set Computing RISC and obviously the previous technology was called Complex Instruction Set Computing ot CISC. RISC was made popular by SUN Microsystems and Digital Eqpt Corp (Nnow merged with Compaq) with its Alpha processor.

These technology of RISC is only relative to CISC i.e. you can call something reduced only in comparison to something with more instructions. For that matter there could be some CPU's with less instructions than certain RISC processors. So what do we call them RISC-ier!!!

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