Over time, the performance of
lesser-performing, faster-evolving products
eventually overtakes the established, slowly evolving classes
served by sustaining technology.

which incidentally stimulated Gates and Allen to start Microsoft. In 1977, the 16-bit 6502 microprocessor and higher-capacity memory chips enabled personal computers for use in the home or classroom built by Apple, Commodore, and Radio Shack—computers that sold in the tens of millions because people bought them to use at home versus corporate buyers. By 1979, the VisiCalc spreadsheet ran on the Apple II establishing it as a “killer app” for personal computers in a work environment. Thus, the trajectory went from a 4-bit data path and limited address space to a 16-bit data path with the ability to access 64KB of memory. This also demonstrates the importance of physical address as an architectural limit. In the paper on DEC’s VAX [ 3], we described the importance of address size on architecture: “There is only one mistake that can be made in a computer design that is difficult to recover from—not providing enough address bits for memory addressing and memory manage-ment…” The 8086/8088 of the first IBM PCs had a 20-bit, or 1MB address space, the operating system using the remaining 384KB.

Concurrent with the introduction of the IBM PC, professional workstations were being created that used the Motorola 68000 CPU with its 32-bit data and address paths (4GB of maximum possible memory). Apple Computer used the Motorola “68K” in its Lisa and Macintosh machines. IBM’s decision to use the Intel architecture with limited addressing, undoubtedly had the effect of impeding the PC by a decade as the industry waited for Intel to evolve architecture to support a larger address and virtual memory space. Hundreds of companies started up to build personal computers (“PC clones”) based on the IBM PC reference design circa 1981. Dozens of

companies also started to build workstations based on a 68K CPU running the UNIX operating system. This was the era of “JAWS” (Just Another WorkStation) to describe efforts at Apollo, HP, IBM, SGI, Sun Microsystems and others based on 32-bit versus 16-bit. Virtually all of these “workstations” were eliminated by simple economics as the PC—based on massive economies of scale and commoditization of both the operating system and all constituent hardware elements—evolved to have sufficient power and pixels.

“Minimal” CMOS Microsystems on a Chip circa 1990 Establish New Classes using Smaller, Less-Expensive, Chips. In 2007, many systems are composed of microprocessor components or “cores” with less than 50,000 transistors per microprocessor core at a time when the leading-edge microprocessor chips have a billion or more transistors (see Figure 3). Such cores using lower cost, less than the state-of-the-art chips and highly effective, rapid design tools allow new, minimal classes to emerge. PDAs, cameras, cell phones, and PADs have all been established using this minimal computer design style based on small cores. In 1990, the Advanced RISC Machine (ARM) formed from a collaboration between Acorn and Apple as the basis for embedded systems that are used as computing platforms and achieved two billion units per year in 2006. Other higher-volume microsystem platforms using 4-, 8-…64-bit architectures including MIPS exist as core architectures for building such systems as part of the very large embedded market.

Rapidly Evolving Killer CMOS Micros circa 1985
Overtake Bipolar ICs to Eliminate Established
Classes. In the early 1980s, the phrase “killer micro”
was introduced by members of the technical comput-