Developments in seemingly more mundane areas were key to the broad acceptance of microprocessors, memories, and other ICs in the seventies. Chief among these was packaging. Although it was not yet the critical element it would become in the 1990s, IC packaging had advanced steadily through the sixties to prepare the way for the larger die sizes in the LSI era. The multichip module (MCM) made its first appearance on the scene in the seventies, helping to bridge the gap between the relatively primitive silicon process technology of the time and the integration that designers wished to achieve. MCMs were a means for engineers to pack more ICs and functionality onto a substrate and within the same leadframe. It wasn't as good as having all of the silicon on the same chip, but it was a meet-in-the-middle kind of approach that still resulted in improved performance compared with ICs packaged separately.
Advances in test equipment came rapidly, too. A lot of digital logic circuits were being designed and built, and a new class of instrumentation would be required to keep up with their mushrooming complexity. Along came the 1973 introduction of the logic analyzer by Hewlett-Packard. The logic analyzer was significant because it allowed designers to verify more complex digital systems at a much faster pace than ever before.
There's little doubt that the microprocessor was the single greatest development in circuit integration in the seventies. But other developments were taking place that led to much greater integration of discrete digital logic. Circuits were becoming so large and complex that designing logic from scratch with discretes was becoming too time-consuming for an industry that was seeing a shift into the shorter design cycles driven by consumer demands. The first level of integration manifested itself as small arrays of bipolar transistors called masterslices. By 1974, the first CMOS gate arrays were introduced, presenting a threat to the discrete logic business. User-programmable logic arrays emerged the following year.
All of this sophisticated silicon began to strain the design infrastructure of the day. Throughout the sixties and into the seventies, transistor-level and early IC design was done pretty much by hand, with designers cutting sheets of rubylith to create lithography masks. By the early 1970s, the circuits' complexity had outstripped the ability—and patience—of designers. The design-automation industry began its ascent. At the printed-circuit-board level, change came with the early Calma and Applicon workstation-based CAD systems, which for the first time allowed designers to enter board layouts into a computer in a fashion that could be edited.
The progress in memories, microprocessors, and other supporting technologies set the stage for computing to move into the mainstream. In 1974, Ed Roberts, the owner of a struggling calculator company in Albuquerque, turned to the new technology in an effort to save his company. Roberts developed what would become known as the first personal computer, the Altair 8800, offering it in kit form to electronic hobbyists.
There wasn't much to the Altair, though. There was no screen, no keyboard, and no software. Programming it was accomplished in machine code using a bank of toggle switches. To some, the machine's shortcomings represented an opportunity for innovation. Two of Roberts' early customers, a student named Bill Gates and his friend Paul Allen, wrote an interpreter to enable the Altair to be programmed in Basic, which they then sold to Roberts. Roberts later hired Allen as a software developer. Gates and Allen went on, of course, to start a little company in Seattle.
Yet another young man who couldn't afford an Altair was inspired to design his own personal computer. Steve Wozniak, with the help of his friend Steve Jobs, worked in Jobs' family's garage until they got their project working. Like another pair of garage-shop entrepreneurs almost 40 years before, Bill Hewlett and Dave Packard, Wozniak and Jobs had a dream and wouldn't be denied. Their Apple Computer Company would evolve into one of the fastest-growing companies in what had become known as Silicon Valley.
As the microprocessor's development had kickstarted the memory IC business, so did the arrival of personal computers spawn other new development paths. The machines needed software to run. Among the early popular applications were the Visicalc spreadsheet program and Wordstar word processor. The growth of the software industry made the new machines much more attractive to businesses and home users.
With software coming up to speed, another crucial need for PCs was data and program storage. Early in the seventies, IBM had introduced the 8-in. floppy disk. For the burgeoning PC industry, a more interesting version came in 1976 when the 5.25-in. floppy arrived. An inexpensive, removable storage media was just the thing for programs and data. In the days before local-area computer networking had become prevalent, removable and easily transportable media was essential for data to be moved from machine to machine.
Local-area networking was, however, already in the works. A researcher at Xerox's Palo Alto Research Center, Bob Metcalfe, had already completed work on a networking protocol that would form the basis for many, many miles of local-area networks—Ethernet. Metcalfe's brainchild still is in broad use today.
Just as the seventies were ending, the pieces were in place for personal computing to go mainstream. Meanwhile in Japan, the first cellular telephones were coming on line. In both Europe and the U.S., fiber optics trials had been completed. These trends, seemingly disparate, would eventually coalesce as the computer and telephone took their initial steps along the path to convergence.
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