IN the pantheon of personal computing, the Linc, in a sense, came first -- more than a decade before Ed Roberts made PC's affordable for ordinary people.
Work started on the Linc, the brainchild of the M.I.T. physicist Wesley A. Clark, in May 1961, and the machine was used for the first time at the National Institutes of Mental Health in Bethesda, Md., the next year to analyze a cat's neural responses.
The term ''Linc'' first referred to the Lincoln Laboratory, an early M.I.T. electronics and computing research center, and eventually became shorthand for Laboratory Instrument Computer.
Each Linc had a tiny screen and keyboard and comprised four metal modules, which together were about as big as two television sets, set side by side and tilted back slightly. The machine, a 12-bit computer, included a one-half megahertz processor. (The 1.8 gigahertz Intel Pentium 4 chips today are more than 3,600 times as fast.) Lincs sold for about $43,000 -- a bargain at the time -- and were ultimately made commercially by Digital Equipment, the first minicomputer company. Fifty Lincs of the original design were built.
The machine had several features that seem quirky by modern standards. For example, it included a knob on its front panel that could slow down or speed up its processor. The machine also included an audio speaker -- intended to give the user feedback on the internal operation of the system.
Historically, the Linc was an important inspiration for much of what would come later in personal computer technology. It combined the research in interactive computing that had begun at M.I.T. in the 1950's with the idea that the entire resources of the machine would be at the disposal of a single user.
''The Linc has my vote for the first personal computer because it had more of the essential ingredients -- small size, low cost, keyboard and display, file system and an interactive operating system,'' said Alan Kay, a computer scientist who pioneered modern personal computing at the Xerox Palo Alto Research Center a decade later.
For Dr. Kay, there was another intangible aspect of the Linc that made it a striking contrast to the existing machines of the era: ''The Linc was lovable,'' he recalled. ''It had what every real personal computer must have: a certain je ne sais quoi that caused a little quiver of excitement and anticipation when one was going to use it.''
The Linc appeared a year before Ivan E. Sutherland's Ph.D. thesis describing a remarkably innovative software design program called Sketchpad. That program, which ran on an early M.I.T.-designed TX-2 minicomputer, was the first to allow graphic images to be created directly on a display screen.
That was a bold step forward, hinting that computers might eventually be used for more than just data processing.
Indeed, the Linc and Sketchpad served as twin inspirations for Dr. Kay, who went on, first as a graduate student at the University of Utah and later at Xerox, to pursue the idea of a Dynabook -- a powerful personal computing machine.
Also influencing his thinking on computer design was work done in the 1960's by Douglas Engelbart's Augmentation Research Laboratory at the Stanford Research Institute, now SRI International, in Menlo Park, Calif.
In a striking demonstration at Brooks Hall in San Francisco in 1968, Dr. Engelbart had taken his group's technology through its paces before an audience of several thousand of the nation's top computer researchers. In an event still referred to as the mother of all demos, Dr. Engelbart first publicly showed many of the attributes of modern personal computing, including the mouse pointing device and a windowing display.
AT Xerox, beginning in 1970, a small team assembled by Dr. Kay began to synthesize these ideas with new ones and to design what they referred to as interim Dynabooks.
The group ultimately built hundreds of prototype personal computers known as Altos. Eventually, Altos were tied together by the Ethernet office network, which had also been developed at the Xerox laboratory.
The Alto was a striking machine, inside and out. Dr. Kay had decreed that most of the machine's memory would be devoted to the display of information rather than processing data -- an unheard-of idea at the time.
The term ''personal computer'' was believed to have first appeared in a Hewlett-Packard advertisement for a desktop calculator in 1968. Four years later, Stewart Brand, writing for Rolling Stone magazine, used the term to describe the work taking place at the Xerox laboratory.
His article began: ''Ready or not, computers are coming to the people.''