The "tongue-in-cheek" essay which appears below was published in EE Times in May 1991 (in a slightly condensed form) with the above "RISC Police" cartoon. It also was presented at the IEEE Asilomar Microcomputer Workshop in April 1991 where it was used as a test of Dave "The Grandfather of RISC" Patterson's sense of humor...he proved not to have any! In addition, after reading the article in EE Times, Roger Ross [CEO of then Cypress' Ross Technologies], contacted SPARC International and tried to get Metaflow Technologies censured by the organization. (SPARC International is Sun Microsystems' [puppet] organization which promotes the so-called "open" SPARC RISC architecture.) To our surprise, Gordon Moore, then Chairman of the Board of Intel Corporation, sent us a nice thank-you letter for writing the EE Times article, and for our "addition of a ray of sanity" to the RISC-CISC debate.
Everything we said then about RISC vs. CISC in the article has turned out to be true! What is somewhat ironic is that at the time we wrote the article, and for the next several years, Metaflow was busy designing a "RISC" SPARC microprocessor for Hyundai Electronics (code named Thunder). A Wall Street Journal headline from that time captured the general mood of the microprocessor design community, which had all but written off CISC...and Intel 80x86 processors. However, what most people failed to grasp at the time is that the so-called RISC chips we were all designing (e.g., SPARC, MIPS, RS-6000, HP-PA, etc.) were, at best, only marginally less complex than the CISC chips against which we were competing (e.g., 80x86 and 68K). In fact, out-of-order, speculative-execution microarchitectures (something Metaflow pioneered) were destined to "level the playing field" and could (and indeed would) erase any performance advantage the "small-is-beautiful" RISC architectures might offer. At the time, we knew in our hearts that RISC wasn't fundamentally better...which you chose (RISC vs. CISC) was a simple marketing decision...not a technical conclusion!
B.D. Lightner - Thu Jul 25 23:37:38 PDT 1996
RISC is just a name that has been chosen for an architecture that has deliberately cut all ties to the past (i.e., software bases) and has implemented the best instruction set possible in light of our more advanced understanding of compiler theory, program behavior, and the shifting performance boundaries between a computational engine and its memory subsystem. Therefore, almost by definition RISC is the future of computing. Over the next five years, a totally new computing standard will emerge based upon RISC architectures. Reduced instruction set computers will completely redefine the computer industry's existing price/performance curve that is based on complex instruction set computers and become the industrial computing standard that will lead us into the 21st century. [From "RISC: The Future Defined" by Roger Ross, SPARC-Line, SPARC International Monthly Newsletter, September 1990.]``RISCing'' outrage by certain readers, we substitute ``communism'' for ``RISC'', and re-phrase the above quotation accordingly:
Communism is just a name that has been chosen for a social and economic theory that has deliberately cut all ties to the past (i.e., outdated capitalistic society) and has implemented the best economic system possible in light of our more advanced understanding of political theory, human behavior, and the shifting class boundaries between the state and its workers. Therefore, almost by definition communism is the future of global economics. Over the next five years, a totally new economic order will emerge based upon communist doctrines. The communist economic system will completely redefine the world's industries' existing distribution of wealth and power that is based on capitalist economic theories and become the industrial social and economic standard that will lead us into the 21st century.People living in communist countries were exposed to daily dosages of similar propaganda. Instinctively, they rejected this as hogwash, and in the end communism itself was rejected (almost) unanimously. The following is a joke told in eastern Europe before the overthrow of the communist party.
At school, young Boris was reprimanded by his teacher because his uniform was wrinkled. Boris' excuse was: ``Comrade teacher, my father turned on the radio this morning and heard the usual story about how in five years our country would produce more tractors than America. He turned off the radio, turned on the TV and saw our party chief telling us about how in ten years the whole world would be communist, and peace would reign forever. My father switched off the TV and forbid my mother from plugging in the iron. He was afraid it might start barking communist slogans too!''
Although communism's problems seem evident today, it wasn't always clear what was wrong with communist economic theory. Before the World War II, a few brilliant minds in England (at Oxford and Cambridge) were honestly embracing communism---in addition to many ``have-nots'' seizing the opportunity to loot the ``haves'' elsewhere in Europe. In the end, communism failed not because it was intellectually flawed---perhaps it was---but because it failed to deliver prosperity and happiness to the masses. And it failed not because it lacked clever leaders or tactical astuteness, but because it deliberately ignored the realities of the marketplace.
It is hard to resist the temptation to draw parallels between the history of communism and the present day RISC versus CISC debate. RISC was masterminded at Berkeley and Stanford, two institutions of higher learning similar in stature to Oxford and Cambridge. RISC architects such as John Hennessy, David Patterson, and others are certainly brilliant, convincing RISC advocates who have enlisted many followers in their campaign to prove the righteousness of RISC. Repeatedly they have intellectually overpowered their lesser counterparts who represent the older, less glamorous (and historically profitable) CISC school. The RISC promoters' cause was joined by ``have-not'' semiconductor companies that hoped to enter the microprocessor business (LSI Logic, IDT, Cypress, etc.)---eager to ``loot'' a share of the business from the established microprocessor vendors (Intel, Motorola, etc.).
At the same time, we have the technical tabloids, incessantly blasting their readers with RISC propaganda pieces, with a style not unlike the communist propaganda of the past few decades. Many of the tabloids predict the total victory of RISC over CISC in a few years---at least one RISC processor on every desk, peace and prosperity for all! We are reminded of young Boris' story.
The microprocessor market seems to follow its own course, ignoring the RISC-CISC rhetoric and zealots' predictions. Intel is steadily moving up in the ranks of semiconductor companies by selling ``historically dead'' and ``intellectually brain-damaged'' CISC microprocessors. At the same time Sun is flooding the market with truckloads of RISC-based SPARCstations. Meanwhile, RISC hasn't saved the likes of CDC and Data General from an ever shrinking market share, nor did it save Tektronix who got into---and back out of---the workstation business one more time. Perhaps Tektronix and others need the help of the ``RISC police'' to enforce cultural purity in the computer industry!
If this turns out to be a war between right and wrong, history tells us that right will probably win. But which camp, RISC or CISC, is on the right side? History has shown us that being young, smart and energetic may not be enough to overcome the old and stagnant. Most often what counts is economic might, not political righteousness. The outcome of World War II was not decided by how brilliant the German officers were, or by how technically clever their weapons makers were, or by how hard their people worked, but ultimately by how many Liberty ships and B-17 bombers the United States could produce each month---and that was a simple function of available resources.
The huge installed base of 80x86-based PC's and the $15,000,000 DOS software market is a hard reality. These customers provide a formidable revenue stream to Intel---a sometimes reluctant promoter of CISC---unmatched by any other microprocessor vendor.
For Intel to do the same thing, it takes a proverbial ``cast of thousand'' engineers---and lots of blood, sweat, and tears. Intel's ``class project'' takes a full three years---and they don't even produce a compiler (they reuse the old one)! In the process Intel develops an in-house CAD/CAE system which allows the management of million-transistor IC designs. This process is very expensive, but it represents only a small part of Intel's gross margins on 80x86 parts. Also, when it is time for the next generation 80x86 part, the CAD tools and Intel's cast of thousand engineers are ready.
On the other hand, the ``small is beautiful'' RISC camp has just begun to wean themselves from ASICs. Faster and cheaper RISC parts are now needed. The world demands memory management units, bus controllers, and cache controllers which run at the same speed as the simple RISC integer units. Guess what? Once you include the necessary support chips which allow the designer to assemble a complete workstation, the total design solution looks equally complex as the design of an 80486! The mythical one-year RISC design cycle becomes three years---the same as competing CISC designs.
And finally, the new RISC designs seem to be getting just as complex as the CISC designs they hope to displace. We hear rumors about superscalar/superpipelined ``super-duper'' RISC designs from both the MIPS and SPARC camps---which last week were preaching the benefits of ``simple is beautiful'' microprocessor design. Next generation RISC designs will be anything but simple. They will require design tools of increased sophistication, and lots of engineers, and that costs money---lots of money.
Will one of the RISC microprocessor vendors have access to enough R&D dollars to produce a multi-million transistor microprocessor in the same time frame as Intel? If so, and if RISC proves it has an intrinsic performance advantage over CISC, the war is over---RISC should have a commanding price/performance advantage over CISC in the marketplace. However, if no RISC vendor can afford the skyrocketing cost of designing multi-million transistor chips, then despite all the advantages offered by clever RISC architects and designers, the B-17's will have won the war.
The table below summarizes some of the design techniques which can overcome CISC's well-known architectural deficiencies:
|CISC Architectural Deficiency||Architectural Compensation|
|Small register set||Dynamic register renaming|
|Destructive register model||Generalized operand renaming|
|Complex, slow instruction decoding||Clever design and lots of transistors|
|Coupled memory references/ALU operations|
(compilers cannot schedule code)
|Parse CISC instructions into dynamically|
scheduled RISC-like parcels
And then there is the question of selling price. More transistors cost more money, and since RISC designs require fewer transistors than CISC designs for the same performance level, RISC should prevail. This is a genuine competitive edge for RISC---but not all transistors are created equal. A half-million transistor TMS34020 graphics chip from Texas Instruments sells for just under $90, while a chip with comparable functionality, yet half the transistor count, implemented as a gate array by your favorite ASIC vendor will cost you four times as much. The reason is both economy of scale (volume) and die size (design budget). Either of these factors can easily wipe out RISC's competitive edge.
As for the promise of vastly improved performance from RISC design techniques, the jury is still out. Today, competing RISC and CISC designs show parity with respect to so-called ``integer'' benchmark programs. The apparent advantage that RISC designs exhibit for floating point intensive benchmarks may be more a reflection of CISC (i.e., 80x86) market emphasis than fundamental architectural advantage. If and when B-17's with floating point turbochargers are needed, one can expect CISC vendors such as Intel to crank up the factories!
So, what is the future of computing into the next century? It's probably too early to tell. The future of the computing industry certainly will be determined by companies like Sun, Compaq, HP, IBM, and DEC, that know how to build and market computers that make real customers happy---the RISC police not withstanding.