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RISC - Later RISC

RISC - Later RISC: Encyclopedia II - RISC - Later RISC

Berkeley's research was not directly commercialized, but the RISC-II design was used by Sun Microsystems to develop the SPARC, by Pyramid Technology to develop their line of mid-range multi-processor machines, and by almost every other company a few years later. It was Sun's use of a RISC chip in their new machines that demonstrated that RISC's benefits were real, and their machines quickly outpaced the competition and essentially took ...

RISC: Encyclopedia II - RISC - Later RISC

RISC - Later RISC

John Hennessy left Stanford (temporarily) to commercialize the MIPS design, starting the company known as MIPS Computer Systems Their first design was a second-generation MIPS chip known as the R2000. MIPS designs went on to become one of the most used RISC chips when they were included in the PlayStation and Nintendo 64 game consoles. Today they are one of the most common embedded processors in use for high-end applications.

IBM learned from the RT-PC failure and would go on to design the RS/6000 based on their new POWER architecture. They then moved their existing AS/400 mainframes to POWER chips, and found much to their surprise that even the very complex instruction set ran considerably faster. The result was the new iSeries. POWER would also find itself moving "down" in scale to produce the PowerPC design, which eliminated many of the "IBM only" instructions and created a single-chip implementation. Today the PowerPC is used in all Apple Macintosh machines, as well as being one of the most commonly used CPUs for automotive applications (some cars have over 10 of them inside). On June 6, 2005 Apple decided to switch to using Intel processors, with the first Apple-x86 based on the Pentium M to be sold sometime near the beginning of 2006.

Almost all other vendors quickly joined. From the UK similar research efforts resulted in the INMOS Transputer, the Acorn Archimedes and the Advanced RISC Machine line, which is a huge success today. Companies with existing CISC designs also quickly joined the revolution. Intel released the i860 and i960 by the late 1980s, although they were not very successful. Motorola built a new design called the 88000 in homage to their famed CISC 68000, but it saw almost no use and they eventually abandoned it and joined IBM to produce the PowerPC. AMD released their 29000 which would go on to become the most popular RISC design of the early 1990s.

Today RISC CPUs (and microcontrollers) represent the vast majority of all CPUs in use. The RISC design technique offers power in even small sizes, and thus has come to completely dominate the market for low-power "embedded" CPUs. Embedded CPUs are by far the largest market for processors: while a family may own one or two PCs, their car(s), cell phones, and other devices may contain a total of dozens of embedded processors. RISC had also completely taken over the market for larger workstations for much of the 90s. After the release of the Sun SPARCstation the other vendors rushed to compete with RISC based solutions of their own. Even the mainframe world is now completely RISC based.

However, despite many successes, RISC has made few inroads into the desktop PC and commodity server markets, where Intel's x86 platform remains the dominant processor architecture (Intel is facing increased competition from AMD, but even AMD's processors implement the x86 platform, or a 64-bit superset known as x86-64). There are three main reasons for this. One, the very large base of proprietary PC applications are written for x86, whereas no RISC platform has a similar installed base, and this meant PC users were locked into the x86 despite a lack of performance. The second is that, although RISC was indeed able to scale up in performance quite quickly and cheaply, Intel took advantage of its large market by spending enormous amounts of money on processor development. Intel could spend many times as much as any RISC manufacturer on improvements in design and manufacturing, making up for inherent flaws in the basic x86 architecture. The third reason is that Intel designers realized that they could apply RISC design philosophies and practices to their architecture. For example, the P6 core of the PentiumPro processor and its successors has special functional units which expand, or "crack", the majority of the CISC instructions into multiple simpler RISC operations. Internally, processors using the P6 core are RISC machines that emulate a CISC architecture.

Consumers are interested in speed, cost per chip, and compatibility with existing software rather than the cost of development of new chips. This has led to an interesting chain of events. As the complexity of developing more and more advanced CPUs increases, the cost of both development and fabrication of high-end CPUs has exploded. The cost gains RISC gave to the CPU designer are now dwarfed by the high costs of developing any modern CPU, and today only the biggest chip makers are capable of making high performing CPUs. The end result is that virtually all RISC platforms with the exception of IBM's POWER/PowerPC have greatly shrunk in scale of development of high performing CPUs (like SPARC and MIPS) or even abandoned (like Alpha and PA-RISC) during the 00s. As of 2004, x86 chips are the fastest CPUs in SPECint displacing all RISC CPUs, and the fastest CPU in SPECfp is the IBM Power 5 processor.

Still, RISC designs have led to a number of successful platforms and architectures, some of the larger ones being:

MIPS's MIPS line, found in most SGI computers and the PlayStation and Nintendo 64 game consoles
IBM's POWER series, used in all of their SuperComputers/mainframes
Freescale (formerly Motorola SPS) and IBM's PowerPC (a subset of the POWER architecture) used in Microsoft's Xbox 360, Nintendo's Revolution and Sony's PlayStation 3 game consoles, and, until recently, all Apple Macintosh computers
Sun's SPARC and UltraSPARC, found in all of their later machines
Hewlett-Packard's PA-RISC HP/PA
DEC Alpha
ARM — Palm, Inc. originally used the (CISC) Motorola 680x0 processors in its early PDAs, but now uses (RISC) ARM processors in its latest PDAs; Nintendo uses an ARM7 CPU in the Game Boy Advance and Nintendo DS handheld game systems. The small Korean company Gamepark also markets the GP32, which uses the ARM9 CPU.