How powerful is a RISC-PowerPC processor over a x86 processor?

[Battousai001]

I have read that RISC type processors such as PowerPC's are more powerful and much more efficient that x86 processors? I would like to ask how powerful/efficient are RISC-PowerPC's compared to x86 processors if same speed in Ghz. are compared?

And why is it x86 processors successful in the desktop market? Why are there much more programs/applications made for the x86 architecture rather than the much powerful and more efficient RISC-PowerPc's?

 

[slpaulson]

x86 is far more successful in the desktop market due to compatability reasons. IBM started using x86 back in the day, and everybody kept with it.

I don't really have enough knowledge of the PowerPC to really compare them to x86 processors efficency wise, but you can't really lump every x86 processor together like that...

 

[Bobthelost]

You could say x86 took off because they scaled better, Motorola did a pisspoor job of increasing the clock speeds of the PPC chip and failed at almost every turn to meet deadlines.

But in truth that's irrelevant to the way Microsoft got a hold of the market share with DOS and never let go. Mircrosoft are the ones to blame for leaving us with this god awful barstardisation of a CISC.

 

[ElFenix]

x86 chips have been risc cores with x86 decoders stuck on them since the pentium pro/k5 days. they're still massively complex. the last x86 processor that didn't decode x86 into some sort of risc instruction for processing was the cyrix 6x86, iirc.

the Power architecture, on which powerpc is based, is pure risc, and is also extremely complex. just like an x86 processor, the power4 is a wide out of order processor.

but, there are applications where big out of order processors are not useful in comparison to simpler designs that can clock higher and are less expensive to make. the xbox360 processor is another powerpc design. but it doesn't feature out of order execution because that feature isn't very useful in games. so xbox360 can feature 3 high clocked cores, rather than 2 lower clocked cores. it's a far simpler design than any x86 processor and the power4 on which it is based (or is it G5-970FX based? either one).

 

[Battousai001]

sorry for this follow up question but is writing programs or applications for a different processor architecture different too? like for example if you want to write program for a risc processor you should study a different programming language? because as I have read programs and applications arent compatible if it is written in a different processor architecture like in gaming (or game consoles) x86 written games are different and cannot run on a risc machine.

and does an emulator for a RISC machine exist for x86 desktops?

and lastly if x86 and risc has same efficiency why is RISC processors much preferred for other electronic devices (specially game consoles) other than desktop/laptop/PDA, and it seems that only desktop/laptops/pda are the ones using x86 while all other electronic devices uses risc? is it because of the ease of making programs and applications for it?

 

[zephyrprime]

Compatibility depends on what level you program at. In theory, you could program in C and the program could work across different processor platforms with a recompile if the same operating system was being used on all machines. In reality this doesn't really pan out so well. (games often have some copiler code in them so that makes porting more difficult for them)

Also, you often end up using libraries that are tied to specific platforms or a certain subset of platforms. Like programs made of linux aren't going to run on windows even though both run on x86.

There are some RISC simulators for x8 I believe for development work.

As for why risc processors are dominant in embedded apps, it's simply because x86 isn't really so efficient. Real implementations of x86 are essentially risc on the inside but they still require a complicated decoded to decode those x86 instructions. For a situation where backwards compatibility doesn't matter, why not just go with risc? Also, the modern risc instruction sets are just a lot nicer and cleaner so why would you purposely choose the more difficult path if you didn't have to? I can't provide you with a complete answer for this question though since I don't know the answer myself. There are some embedded applications where x86 is used though. The current crop of hddvd players actually use a P4 I believe. Nothing can beat it a x86 processor for price/performance ratio sometimes.

 

[Battousai001]

Just a follow up question. does the "bits" of a cpu matters in its efficiency and power (32 bit compared to 128bit of different cpu architecture)? like for example this article I found on wikipedia regarding the "emotion engine cpu of the playstation 2" emotion engine runs at 299Mhz.

"The Emotion Engine is the name of the Central Processing Unit (CPU) used in Sony PlayStation 2 video game consoles. It was jointly designed by Toshiba and Sony and began mass production in 1999. According to MicroDesign Resources, it is two times faster than a 733 MHz Pentium III and 15 times faster than a 400 MHz Celeron at handling tasks like full-motion video.

The Emotion Engine's data bus, cache memory as well as all registers are implemented in 128 bit technology, integrated on a single 0.18 micrometer process technology chip (making it the first commercial 128 bit CPU). The Emotion Engine, based on the MIPS R5900, is sort of a combination CPU and DSP processor, whose main function is simulating 3D worlds."

PS2 are even combined to turn into supercomputer: http://news.bbc.co.uk/1/hi/technology/2940422.stm

I know the first Xbox was using a x86 P3-Celeron cpu clocked at 733Mhz, and sometimes people say it was the most powerful game console during that time (it can even play games at HD!). Does this contradict the article or is it just marketing stuff made by users?