In December 1947, Eckert and Mauchly formed Eckert-Mauchly Computer Corporation. Their first machine, the BINAC, was built for Northrop and was shown in August 1949. After some financial difficulties, their firm was acquired by Remington-Rand, where they built the UNIVAC I (Universal Automatic
Computer), designed to be sold as a general-purpose computer (Figure e1.12.2).
Originally delivered in June 1951, UNIVAC I sold for about $1 million and was the first successful commercial computer—48 systems were built! This early machine, along with many other fascinating pieces of computer lore, may be seen at the Computer History Museum in Mountain View, California.
FIGURE e1.12.2 UNIVAC I, the first commercial computer in the United States. It correctly predicted the outcome of the 1952 presidential election, but its initial forecast was withheld from broadcast because experts doubted the use of such early results.
IBM had been in the punched card and office automation business but didn’t start building computers until 1950. The first IBM computer, the IBM 701, shipped in 1952, and eventually 19 units were sold. In the early 1950s, many people were pessimistic about the future of computers, believing that the market and opportunities for these “highly specialized” machines were quite limited.
In 1964, after investing $5 billion, IBM made a bold move with the announcement of the System/360. An IBM spokesman said the following at the time:
We are not at all humble in this announcement. This is the most important product announcement that this corporation has ever made in its history. It’s not a computer in any previous sense. It’s not a product, but a line of products … that spans in performance from the very low part of the computer line to the very high.
1.12 Historical Perspective and Further Reading 54.e5
Moving the idea of the architecture abstraction into commercial reality, IBM announced six implementations of the System/360 architecture that varied in price and performance by a factor of 25. Figure e1.12.3 shows four of these models. IBM bet its company on the success of a computer family, and IBM won. The System/360 and its successors dominated the large computer market.
About a year later, Digital Equipment Corporation (DEC) unveiled the PDP-8, the first commercial minicomputer. This small machine was a breakthrough in low-cost design, allowing DEC to offer a computer for under $20,000.
Minicomputers were the forerunners of microprocessors, with Intel inventing the first microprocessor in 1971—the Intel 4004.
FIGURE e1.12.3 IBM System/360 computers: models 40, 50, 65, and 75 were all introduced in 1964. These four models varied in cost and performance by a factor of almost 10; it grows to 25 if we include models 20 and 30 (not shown). The clock rate, range of memory sizes, and approximate price for only the processor and memory of average size: (a) model 40, 1.6 MHz, 32 KB–256 KB, $225,000; (b) model 50, 2.0 MHz, 128 KB–256 KB, $550,000; (c) model 65, 5.0 MHz, 256 KB–1 MB, $1,200,000; and (d) model 75, 5.1 MHz, 256 KB–1 MB,
$1,900,000. Adding I/O devices typically increased the price by factors of 1.8 to 3.5, with higher factors for cheaper models.
In 1963 came the announcement of the first supercomputer. This announcement came neither from the large companies nor even from the high-tech centers.
Seymour Cray led the design of the Control Data Corporation CDC 6600 in Minnesota. This machine included many ideas that are beginning to be found in the latest microprocessors. Cray later left CDC to form Cray Research, Inc., in Wisconsin. In 1976, he announced the Cray-1 (Figure e1.12.4). This machine was simultaneously the fastest in the world, the most expensive, and the computer with the best cost/performance for scientific programs.
FIGURE e1.12.4 Cray-1, the first commercial vector supercomputer, announced in 1976.
This machine had the unusual distinction of being both the fastest computer for scientific applications and the computer with the best price/performance for those applications. Viewed from the top, the computer looks like the letter C. Seymour Cray passed away in 1996 because of injuries sustained in an automobile accident. At the time of his death, this 70-year-old computer pioneer was working on his vision of the next generation of supercomputers. (See www.cray.com for more details.)
While Seymour Cray was creating the world’s most expensive computer, other designers around the world were looking at using the microprocessor to create a computer so cheap that you could have it at home. There is no single fountainhead for the personal computer, but in 1977, the Apple IIe (Figure e1.12.5) from Steve Jobs and Steve Wozniak set standards for low cost, high volume, and high reliability that defined the personal computer industry.
1.12 Historical Perspective and Further Reading 54.e7
However, even with a 4-year head start, Apple’s personal computers finished second in popularity. The IBM Personal Computer, announced in 1981, became the best-selling computer of any kind; its success gave Intel the most popular microprocessor and Microsoft the most popular operating system. Today, the most popular CD is the Microsoft operating system, even though it costs many times more than a music CD! Of course, over the more than 30 years that the IBM-compatible personal computer has existed, it has evolved greatly. In fact, the first personal computers had 16-bit processors and 64 kilobytes of memory, and a low-density, slow floppy disk was the only nonvolatile storage! Floppy disks were originally developed by IBM for loading diagnostic programs in mainframes, but were a major I/O device in personal computers for almost 20 years before the advent of CDs and networking made them obsolete as a method for exchanging data.
Of course, Intel microprocessors have also evolved since the first PC, which used a 16-bit processor with an 8-bit external interface! In Chapter 2, we write about the evolution of the Intel architecture.
The first personal computers were quite simple, with little or no graphics capability, no pointing devices, and primitive operating systems compared to those of today. The computer that inspired many of the architectural and software concepts that characterize the modern desktop machines was the Xerox Alto, shown in Figure e1.12.6. The Alto was created as an experimental prototype of a future computer; there were several hundred Altos built, including a significant
FIGURE e1.12.5 The Apple IIc Plus. Designed by Steve Wozniak, the Apple IIc set standards of cost and reliability for the industry.
FIGURE e1.12.6 The Xerox Alto was the primary inspiration for the modern desktop computer. It included a mouse, a bit-mapped scheme, a Windows-based user interface, and a local network connection.
number that were donated to universities. Among the technologies incorporated in the Alto were:
■ a bit-mapped graphics display integrated with a computer (earlier graphics displays acted as terminals, usually connected to larger computers)
■ a mouse, which was invented earlier, but included on every Alto and used extensively in the user interface
■ a local area network (LAN), which became the precursor to the Ethernet
■ a user interface based on Windows and featuring a WYSIWYG (what you see is what you get) editor and interactive drawing programs
1.12 Historical Perspective and Further Reading 54.e9
In addition, both file servers and print servers were developed and interfaced via the local area network, and connections between the local area network and the wide area ARPAnet produced the first versions of Internet-style networking.
The Xerox Alto was incredibly influential and clearly affected the design of a wide variety of computers and software systems, including the Apple Macintosh, the IBM-compatible PC, MacOS and Windows, and Sun and other early workstations.
Measuring Performance
From the earliest days of computing, designers have specified performance goals—
ENIAC was to be 1000 times faster than the Harvard Mark-I, and the IBM Stretch (7030) was to be 100 times faster than the fastest computer then in existence. What wasn’t clear, though, was how this performance was to be measured.
The original measure of performance was the time required to perform an individual operation, such as addition. Since most instructions took the same execution time, the timing of one was the same as the others. As the execution times of instructions in a computer became more diverse, however, the time required for one operation was no longer useful for comparisons.
To consider these differences, an instruction mix was calculated by measuring the relative frequency of instructions in a computer across many programs.
Multiplying the time for each instruction by its weight in the mix gave the user the average instruction execution time. (If measured in clock cycles, average instruction execution time is the same as average CPI.) Since instruction sets were similar, this was a more precise comparison than add times. From average instruction execution time, then, it was only a small step to MIPS. MIPS had the virtue of being easy to understand; hence, it grew in popularity.