An alternative to the bus-oriented Altair design was the single-board microcomputer like the IMP-16C. Miniaturization made it possible to put a small computer comprised of a microprocessor, memory, and support circuitry on a single (though large) circuit board. Such a single-board design is economical because it saves the expense of the bus connector and redundant circuitry on supplemental circuit boards.
Two hobbyists, Steve Jobs and Steve Wozniak, experimented with this approach and, in 1976, built boards they called the Apple Computer. But, even back then, the market for products aimed for people born with soldering irons in hand was limited, and the original Apple circuit board computer is now regarded as a curiosity, an interesting antique for computer collectors.
But the next attempt by Jobs and Wozniak proved a hit. In 1977, the twosome combined an innovative ready-made computer and professional marketing. The result was the Apple II, the longest lived of all small computer models. The Apple II blazed a path as the best of both worlds, combining a single board for consistency, efficiency, and economy with a dedicated expansion bus into which accessories (and some necessities) could be attached.
The Apple II was based on a single microprocessor and was a single-board computer because everything needed to make it work (at least in the most rudimentary way) was built onto a single glass-epoxy printed circuit board. Its expansion bus provided a way of connecting additional printed circuit boards almost directly to the microprocessor. Even the keyboard was combined into the attractively designed plastic case that housed all the electronics-a simple, practical, and cost effective approach.
The central processing unit of the Apple II was its microprocessor, the 6502 made by Motorola. At the time, this was a respectable chip choice. It could perform eight-bit calculations at an operating speed of about one million cycles per second (megahertz).
Compared to the personal computers of today, the Apple II was rudimentary. The straightforward original design of the Apple II made no provision for lowercase letters, could put only 40 columns of text across the screen, and could be bought with as little as 8K of memory. For more permanent storage, it could route data from its electronic memory onto magnetic tape using a conventional audio cassette machine. Compared to what came before, however, it was groundbreaking. You could buy an Apple II, pull it from its box, plug it in, and have a working computer. Previous small computers universally required at least a moderate degree of technical knowledge, a great deal of patience to withstand the tedious process of assembling parts not necessarily meant to work together, and an overriding faith that they would, in fact, work.
Later, Apple added features to bring the Apple II up to par with other PCs, including lowercase characters in 80 columns, bitmapped graphics, and disk storage controlled by Apple DOS. But in the early 1980s Apple's development attention shifted to the Macintosh, a more powerful architecture based on the Motorola MC68000 microprocessor. The Macintosh was introduced in January 1984.
The original Apple II design was adapted through several models, which later found their primary application in elementary schools. The last models in the Apple II product line were discontinued in 1993.
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