Code_ The Hidden Language of Computer Hardware and Software - Charles Petzold [160]
Many of the early enthusiasts of interactive graphical computing (although not Engelbart) came together at Xerox, fortunately at a time when raster displays became economically feasible. Xerox had founded the Palo Alto Research Center (PARC) in 1970 in part to help develop products that would allow the company to enter the computer industry. Perhaps the most famous visionary at PARC was Alan Kay (born 1940), who encountered Van Bush's microfilm library (in a short story by Robert Heinlein) when he was 14, and who had already conceived of a portable computer he called the Dynabook.
The first big project at PARC was the Alto, designed and built between 1972 and 1973. By the standards of those years, it was an impressive piece of work. The floor-standing system unit had 16-bit processing, two 3-MB disk drives, 128 KB of memory (expandable to 512 KB), and a mouse with three buttons. Because the Alto preceded the availability of 16-bit single-chip microprocessors, the Alto processor had to be built from about 200 integrated circuits.
The video display was one of the several unusual aspects of the Alto. The screen was approximately the size and shape of a sheet of paper—8 inches wide and 10 inches high. It ran in a raster graphics mode with 606 pixels horizontally by 808 pixels vertically, for a total of 489,648 pixels. One bit of memory was devoted to each pixel, which meant that each pixel could be either black or white. The total amount of memory devoted to the video display was 64 KB, which was part of the address space of the processor.
By writing into this video display memory, software could draw pictures on the screen or display text in different fonts and sizes. By rolling the mouse on the desk, the user of the Alto could position a pointer on the screen and interact with on-screen objects. Rather than treating the video display in the same way as the teletypewriter—linearly echoing user input and writing out program output—the screen became a two-dimensional high-density array of information and a more direct source of user input.
Over the remainder of the 1970s, programs written for the Alto developed some very interesting characteristics. Multiple programs were put into windows and displayed on the same screen simultaneously. The video graphics of the Alto allowed software to go beyond text and truly mirror the user's imagination. Graphical objects (such as buttons and menus and little pictures called icons) became part of the user interface. The mouse was used for selecting windows or triggering the graphical objects to perform program functions.
This was software that went beyond the user interface into user intimacy, software that facilitated the extension of the computer into realms beyond those of simple number crunching. This was software that was designed—to quote the title of a legendary paper written by Douglas Engelbart in 1963—"for the Augmentation of Man's Intellect."
What PARC developed in the Alto was the beginnings of the graphical user interface, or GUI (pronounced gooey). But Xerox didn't sell the Alto (one would have cost over $30,000 if they had), and over a decade passed before the ideas in the Alto would be embodied in a successful consumer product.
In 1979, Steve Jobs and a contingent from Apple Computer visited PARC and were quite impressed with what they saw. But it took them over three years to introduce a computer that had a graphical interface. This was the ill-fated Apple Lisa in January 1983. A year later, however, Apple introduced the much more successful Macintosh.
The original Macintosh had a Motorola 68000 microprocessor, 64 KB of ROM, 128 KB of RAM, a 3½-inch diskette drive (storing 400 KB per diskette), a keyboard, a mouse, and a video display capable of displaying 512 pixels horizontally by 342 pixels vertically. (The CRT itself measured only 9 inches diagonally.) That's a total of 175,104 pixels. Each pixel was associated with 1 bit of memory and could be colored