HIR Issue 10: RISC, CISC and The concept of the Power-PC

By. Asmodian X

eZine lover (@eZine)

Published in

Hackers Information Report

· 3 years ago

In this article I plan to outline the Power-PC series processors, and their origins. I also intend to draw out the differences of RISC chips and CISC chips.

This article is intended for intermediate audiences who Know the basics on how a computer works, and are wondering what the big deal with these expensive Workstations and servers that are non-Intel.

Section 1: Why.
Section 2: IBM, Apple, and other large faceless corporations.
Section 3: Intended uses
Section 4: RISC Vs. CISC
Section 5: Fact Vs. Fiction (seeing through marketing ploys)
Section 6: Summary
Section 7: Resources

Section 1: Why?

Why am I writing this article, Intel based designs are cleaning up in the PC market, MAC's are still the under dog, what's the point? Well, if you have ever argued with a Mac enthusiast about who's better, and walked away victorious, but secretly wondered what really lies underneath the hood of one of the new(er) power Mac's. Or if you are wondering what the real difference between a Desktop and a workstation, then this article might be able to shed some light on the subject at hand. I am primarily focusing on Mac's because they are the more popular source of PPC machines.

<RANT>
As a company, apple sucks, their OS suck only if you don't want to conform to their standards. Mac OS's primary attributes is that is has a very small learning curve. The hardware is cool if you don't mind the proprietary shit that apple pulls.
</RANT>

Section 2: IBM, Apple and other large faceless corporations.

xx IBM xx
IBM is the leader in High end, workstations, and super computers. IBM started out with a processor line called the Power processor which was featured in its RS/6000 series of workstations. The Power processor was a Full RISC processor. The modern Power-PC processor is a direct derivative of IBM's Power processor.

IBM has its own chip manufacturing capability's.

xx Apple xx
Apple specializes in consumer grade graphics personal computer. Apples designs have generally featured RISC processors manufactured by Motorola. Apple chose RISC because it is less complex and faster than the CISC architecture. Apple markets to people who are not technically literate. Hence why a great percentage of Mac users are scoffed at by their PC counterparts. Typically most Mac users tend to gravitate around graphic design, and journalism.

xx Intel xx
Intel originally started out like IBM, catering to the upper end Server market. Then a couple of engineers designed a processor based on the 4004 series calculator chip. The processor series eventually lead to the advent of the 8086 chip, which was featured in IBM's new Personal computer. IBM PC's were introduced into an office environment which caused growth in business application development, and Engineering. Because of this, IBM computers were slow to adopt a graphical user interface. Also because of the business nature, new computers needed to be backward compatible to allow integration with existing PC's. Because of this, Intel's chips grew into CISC chips or (Complex Instruction Set Computing)

Because Intel and IBM did not take the market seriously, competitors flourished, and proprietary architectures withered away due to the advent of open standards, and industry standards.

Section 3: Intended Uses Of the Power-PC

IBM and several competitors saw that RISC was the technology of the future. The problem was who's version of RISC to go with. So rather than Re-inventing RISC, They built the standard on top of the existing IBM Power Processor. Power-PC 60x Chips can run IBM power code natively with one or two hicups when it tries to run some Buffer Clearing Instructions. IBM compensated for this shortcoming with some emulation code in their AIX operating system. IBM Implemented the Power-PC on their RS/6000 Workstations in place of the Power Processor.

Apple entered the game wanting to compete with the new Intel Pentium chip. In the Power-PC Apple saw Superior performance and Lower production costs. One little problem, The M68000 series instructions did not work on the Power-PC chip. To compensate for this problem, Apple, included emulation for the Motorola based applications and operating system code. Apple (like all of the other attendees) was very proprietary, and on the first few batches (Like the Power-Mac 7100) utilized the old NuBus Peripheral Bus. Because of this, and other proprietary problems, the early PowerMACs were unable to boot alternative operating systems with out at least some form of MacOS assisting it.

I believe Mac OS will continue to emulate the old M68k chips, but for the most part the Operating system has slowly been ported over to the PPC platform.

Section 4: RISC Versus CISC

In concept RISC Provides More speed for less price. RISC chips use less logic circuits to attain the same raw performance of a CISC processor. A CISC chip provides backwards compatibility which eats into performance, and cost. Simply speaking it is more efficient than the CISC platforms.

However, RISC has some down falls. Apples choice to emulate its older Motorola Processor pointed out its own need for backwards compatibility. Emulating a processor logically is slower than adding that functionality to the chip itself. maintaining software that will work on older processors but will not work on newer ones is much more difficult than just dropping a new system into an office and have it work seamlessly with existing machines. So CISC computers are much more versatile than their RISC counterparts in that they can be implemented with out requiring special emulation software, it can run the older programs with out a problem, and faster than the older computers can. The early advent of open standards allowed for the porting of Operating system software and Applications to the PC platform much easier than most RISC systems which were and in some respects are still proprietary in nature. Simply put CISC is more versatile in use, and easier to develop for, and produce, there for it is more popular.

To compare CISC versus RISC, one might compare a VHS to a Beta.

(Note: a while back there was a battle of standards, and industry standard called VHS, and Sony's Beta standard VCR. VHS won because of popularity, SONY was a better technology, but was proprietary, and inflexible)

Section 5: Fact Vs. Fiction

Fiction: Power-PC's can run PC code natively
Fact: Power-PC's must use emulation software, and some times hardware.

Fiction: Mac application software can be run on any kind of macintosh.
Fact: Power Mac's emulate their older m68k counterparts otherwise running older software would be impossible.

Fiction: A power Mac G4 is over three times as fast as a Pentium.
Fact: Thats true from the perspective that a Pentium II 300 is over three times as fast as a 486 DX4 100. ( Point being that CISC will always be slower, especially if you testing a 64 bit processor, versus a 128 bit processor. That statement is called a "Red Herring"; A true statement that has nothing to do with the subject at hand. )

Section 6: Summary

Indeed, the RISC architecture is better at raw power. Yet CISC is more versatile, and easier to implement. CISC generally is also easier to develop for, because you don't have to re-invent the wheel all over again. The extra instructions you can use save a bit of time in compiling .

Its kind of a trade off.