[This post is part of “A Bicycle for the Mind.” The complete series can be found here.]

The Early Electronics Hobby

A certain pattern of technological development recurred many times in the decades around the turn of the twentieth century: a scattered hobby community, tinkering with a new idea, develops it to the point where those hobbyists can sell it as a product. This sets off a frenzy of small entrepreneurial firms, competing to sell to other hobbyists and early adopters. Finally, a handful of firms grow to the point where they can drive down costs through economies of scale and put their smaller competitors out of business. Bicycles, automobiles, airplanes, and radio broadcasting all developed more or less in this way.

The personal computer followed this same pattern; indeed, it marks the very last time that a “high-tech” piece of hardware emerged from this kind of hobby-led development. Since that time, new hardware technology has typically depended on new microchips. That is a capital barrier far too high for hobbyists to surmount; but as we have seen, the computer hobbyists lucked into ready-made microchips created for other reasons, but already suited to their purposes.

The hobby culture that created the personal computer was historically continuous with the American radio hobby culture of the early twentieth-century, and, to a surprising degree, the foundations of that culture can be traced back to the efforts of one man: Hugo Gernsback. Gernsback (born Gernsbacher, to well-off German Jewish parents) came to the United States from Luxembourg in 1904 at the age of nineteen, shortly after his father’s death. Already fascinated by electrical equipment, American culture, and the fiction of Jules Verne and H.G. Wells, he started a business, the Electro Importing Company, in Manhattan, that offered both retail and mail-order sales of radios and related equipment. His company catalog evolved into a magazine, Modern Electrics, and Gernsback evolved into a publisher and community builder (he founded the Wireless Association of America in 1909 and the Radio League of America in 1915), a role he relished for the rest of his working life.[1]

The culture that Gernsback nurtured valued hands-on tinkering and forward-looking futurism, and in fact viewed them as two sides of the same coin. Science fiction (“scientifiction,” as Gernsback called it) writing and practical invention went hand in hand, for both were processes for pulling the future into the present. In a May 1909 article in Modern Electrics, for example, Gernsback opined on the prospects for radio communication with Mars: “If we base transmission between the earth and Mars at the same figure as transmission over the earth, a simple calculation will reveal that we must have the enormous power of 70,000 K. W. to our disposition in order to reach Mars,” and went on to propose a plan for building such a transmitter within the next fifteen or twenty years.

As science fiction emerged as its own genre with its own publications in the 1920s (many of them also edited by Gernsback), this kind of speculative article mostly disappeared from the pages of electronic hobby magazines. Gernsback himself occasionally dropped in with an editorial, such as a 1962 piece in Radio-Electronics on computer intelligence, but the median electronic magazine article had a much more practical focus. Readers were typically hobbyists looking for new projects to build or service technicians wanting to keep up with the latest hardware and industry trends.[2]

Nonetheless, the electronic hobbyists were always on the lookout for the new, for the expanding edge of the possible: from vacuum tubes, to televisions, to transistors, and beyond. It’s no surprise that this same group would develop an early interest in building computers. Nearly everyone who we find building (or trying to build) a personal or home computer prior to 1977 had close ties to the electronic hobby community.

The Gernsback story also highlights a common feature of hobby communities of all sorts. A subset of radio enthusiasts, seeing the possibility of making money by fulfilling the needs of their fellow hobbyists, started manufacturing businesses to make new equipment for hobby projects, retail businesses to sell that equipment, or publishing businesses to keep the community informed on new equipment and other hobby news. Many of these enterprises made little or no money (at least at first), and were fueled as much by personal passion as by the profit motive; they were the work of hobby-entrepreneurs. It was this kind of hobby-entrepreneur who would first make personal computers available to the public.

The First Personal Computer Hobbyists

The first electronic hobbyist to take an interest in building computers, whom we know of, was Stephen Gray. In 1966, he founded the Amateur Computer Society (ACS), an organization that existed mainly to produce a series of quarterly newsletters typed and mimeographed by Gray himself. Gray has little to say about his own biography in the newsletter or in later reflections on the ACS. He reveals that he worked as an editor of the trade magazine Electronics, that he lived in Manhattan and then Darien, Connecticut, that he had been trying to build a computer of his own for several years, and little else. But he clearly knew the radio hobby world. In the fourth, February 1967, number of his newsletter, he floated the idea of a “Standard Amateur Computer Kit” (SACK) that would provide an economical starting point for new hobbyists, writing that,[3]

Amateur computer builders are now much like the early radio amateurs. There’s a lot of home-brew equipment, much patchwork, and most commercial stuff is just too expensive. The ACS can help advance the state of the amateur computer art by designing a standard amateur computer, or at least setting up the specs for one. Although the mere idea of a standard computer makes the true blue home-brew types shudder, the fact is that amateur radio would not be where it is today without the kits and the off-the-shelf equipment available.[4]

By the Spring of 1967, Gray had found seventy like-minded members through advertisements in trade and hobby publications, most of them in the United States, but a handful in Canada, Europe, and Japan. We know little about the backgrounds or motivations of these men (and they were exclusively men), but when their employment is mentioned, they are found at major computer, electronics, or aerospace firms; at national labs; or at large universities. We can surmise that most worked with or on computers as part of their day job.

A few letter writers disclose prior involvement in hobby electronics and radio, and from the many references to attempts to imitate the PDP-8 architecture, we can also guess that many members had some association with DEC minicomputer culture. It is speculative but plausible to guess that the 1965 release of the PDP-8 might have instigated Gray’s own home computer project and the later creation of the ACS. Its relatively low price, compact size, and simple design may have catalyzed the notion that home computers lay just out of reach, at least for Gray and his band of like-minded enthusiasts.

Whatever their backgrounds and motivations, the efforts of these amateurs to actually builda computer proved mostly fruitless in these early years. The January 1968 newsletter reported a grand total of two survey respondents who possessed an actual working computer, though respondents as a whole had sunk an average of two years and $650 on their projects ($6,000 in 2024 dollars). The problem of assembling one’s own computer would daunt even the most skilled electronic hobbyist: no microprocessors existed, nor any integrated circuit memory chips, and indeed virtually no chips of any kind, at least at prices a “homebrewer” could afford.

Both of the two complete computers reported in the survey were built from hand-wired transistor logic. One was constructed from the parts of an old nuclear power system control computer, PRODAC IV. Jim Sutherland took the PRODAC’s remains home from his work at Westinghouse after its retirement, and re-dubbed it the ECHO IV (for Electronic Computing Home Operator). Though technically a “home” computer, to borrow an existing computer from work was not a path that most would-be home-brewers could follow. This hardly had the makings of a technological revolution. The other complete “computer,” the EL-65 by Hans Ellenberger of Switzerland, on the other hand, was truly an electronic desktop calculator; it could perform arithmetic ably enough, but could not be programmed. [5]

The Emergence of the Hobby-Entrepreneur

As integrated circuit technology got better and cheaper, the situation for would-be computer builders gradually improved. By 1971, the first, very feeble, home computer kits appeared on the market, the first signs of Gray’s “SACK.” Though neither used a microprocessor, they took advantage of the falling prices of integrated circuits: the CPU of each consisted of dozens of small chips wired together. The first was the National Radio Institute (NRI) 832, the hardware accompaniment to a computer technician course disseminated by the NRI, and priced at about $500. Unsurprisingly, the designer, Lou Freznel, was a radio hobby enthusiast, and a subscriber to Stephen Gray’s ACS Newsletter. But the NRI 832 is barely recognizable as a functional computer: it had a measly sixteen 8-bit words of read-only memory, configured by mechanical switches (with an additional sixteen bytes of random-access memory available for purchase).[6]

The $750 Kenbak-1 that appeared the same year was nominally more capable, with 256 bytes of memory, though implemented with shift-register chips (accessible one bit at a time), not random-access memory. Indeed, the entire machine had a serial-processing architecture, processing only one bit at a time through the CPU, and ran at only about 1,000 instructions per second—very slow for an electronic computer. Like the NRI 832, it offered only switches as input and only a small panel of display lights for showing register contents as output. Its creator, John Blankenbaker, was a radio lover from boyhood before enrolling as an electronics technician in the Navy. He began working on computers in the 1950s, beginning with the Bureau of Standards SEAC. Intrigued by the possibility of bringing a computer home, he tinkered with spare parts for making his own computer for years, becoming his own private ACS. By 1971 he thought he had a saleable device that could be used for teaching programming, and he formed the eponymous “Kenbak” company to sell it.[7]

Blankenbaker was the first of the amateur computerists to try to bring his passion to market; the first hobby-entrepreneur of the personal computer. He was not the most successful. I found no records of the sales of the NRI 832, but by Blankenbaker’s own testimony, only forty-four Kenbak-Is were sold. Here were home computer kits readily available at a reasonable price, four years before Altair. Why did they fall flat? As we have seen, most members of the Amateur Computer Society had aimed to make a PDP-8 or something like it; this was the most familiar computer of the 1960s and early 1970s, and provided the mental model for what a home computer could and should be. The NRI 832 and Kenbak-I came nowhere close to the capabilities of a PDP-8, nor were they designed to be extensible or expandable in any way that might allow them to transcend their basic beginnings. These were not machines to stir the imaginative loins of the would-be home computer owner.

Hobby-Entrepreneurship in the Open

These early, halting steps towards a home computer, from Stephen Gray to the Kenbak-I, took place in the shadows, unknown to all but a few, the hidden passion of a handful of enthusiasts exchanging hand-printed newsletters. But several years later, the dream of a home computer burst into the open in a series of stories and advertisements in major hobby magazines. Microprocessors had become widely available. For those hooked on the excitement of interacting one-on-one with a computer, the possibility of owning their own machine felt tantalizing close. A new group of hobby-entrepreneurs now tried to make their mark by providing computer kits to their fellow enthusiasts, with rather more success than NRI and Kenbak.

The overture came in the fall of 1973, with Don Lancaster’s “TV Typewriter,” featured on the cover of the September issue of Radio-Electronics (a Gernsback publication, though Gernsback himself was, by then, several years dead). Lancaster, like most of the people we have met in this chapter, was an amateur “ham” radio operator and electronics tinkerer. Though he had a day job at Goodyear Aerospace in Phoenix, Arizona, he figured out how to make a few extra bucks from his hobby by publishing projects in magazines and selling pre-built circuit boards for those projects via a Texas hobby firm called Southwest Technical Products (SWTPC).

His TV Typewriter was, of course, not a computer at all, but the excitement it generated certainly derived from its association with computers. One of many obstacles to a useful home computer was the lack of a practical output device: something more useful than the handful of glowing lights that the Kenbak-I sported, but cheaper and more compact than the then-standard computer input/output device, a bulky teletype terminal. Lancaster’s electronic keyboard, which required about $120 in parts, could hook up to an ordinary television and turn it into a video text terminal, displaying up to sixteen lines of thirty-two characters each. Shift-registers continued to be the only cheap form of semiconductor memory, and so that was what Lancaster used for storing the characters to be displayed on screen. Lancaster gave the parts list and schematic to the TV Typewriter away for free, but made money by selling pre-built subassemblies via SWTPC that saved buyers time and effort, and by publishing guidebooks likethe TV Typewriter Cookbook.[8]

The next major landmark appeared six months later in a ham radio magazine, QST, named after the three-letter ham code for “calling all stations.” A small ad touted the availability of “THE TOTALLY NEW AND THE VERY FIRST MINI-COMPUTER DESIGNED FOR THE ELECTRONIC/COMPUTER HOBBYIST” with kit prices as low as $440. This was the SCELBI 8-H, the first computer kit based around a microprocessor, in this case the Intel 8008. Its creator, Nat Wadsworth, lived in Connecticut, and became enthusiastic about the microprocessor after attending a seminar given by Intel in 1972, as part of his job as an electrical engineer at an electronics firm. Wadsworth was another ham radio enthusiast, and already enough of a personal computing obsessive to have purchased a surplus DEC PDP-8 at a discount for home use (he paid “only” $2,000, about $15,000 in 2024 dollars). Since his employer did not share his belief in the 8008, he looked for another outlet for his enthusiasm, and teamed up with two other engineers to develop what became the SCELBI-8H (for SCientific ELectronic BIological). Their ads drew thousands of responses and hundreds of orders over the following months, though they ended up losing money on every machine sold.[9]

A similar machine appeared several months later, this time as a hobby magazine story, on the cover the July 1974 issue of Radio-Electronics: “Build the Mark-8 Minicomputer,” ran the headline (notice again the “minicomputer” terminology: a PDP-8 of one’s own remained the dream). The Mark-8 came from Jonathan Titus, a grad student from Virginia, who had built his own 8008-based computer and wanted to share the design with the rest of the hobby. Unlike SCELBI, he did not sell it as a complete machine or even a kit: he expected the Radio-Electronics reader to buy and assemble everything themselves. That is not to say that Titus made no money: he followed a hobby-entrepreneur business model similar to Don Lancaster’s, offering an instructional guidebook for $5, and making some pre-made boards available for sale through a retailer in New Jersey, Techniques, Inc.

The SCELBI-8H and Mark-8 looked much more like a “real” minicomputer than the NRI 832 or Kenbak-I. A hobbyist hungry for a PDP-8-like machine of their own could recognize in this generation of machines something edible, at least. Both used an eight-bit parallel processor, not an antiquated bit-serial architecture, came with one kilobyte of random-access memory, and were designed to support textual input/output devices. Most importantly both could be extended with additional memory or I/O cards. These were computers you could tinker with, that could become an ongoing hobby project in and of themselves. A ham radio operator and engineering student in Austin, Texas named Terry Ritter spent over a year getting his Mark-8 fully operational with all of the accessories that he wanted, including an oscilloscope display and cassette tape storage.[10]

In the second half of 1974, a community of hundreds of hobbyists like Ritter began to form around 8008-based computers, significantly larger than the tiny cadre of Amateur Computer Society members. In September 1974, Hal Singer began publishing the Mark-8 User Group Newsletter (later renamed the Micro-8 Newsletter) for 8008 enthusiastsout of his office at the Cabrillo High School Computer Center in Lompoc, California. He attracted readers from all across the country: California and New York, yes, but also Iowa, Missouri, and Indiana. Hal Chamberlain started the Computer Hobbyist newsletter two months later. Hobby entrepreneurship expanded around the new machines as well: Robert Suding formed a company in Denver called the Digital Group to sell a packet of upgrade plans for the Mark-8.[11]

The first tender blossoms of a hobby computer community had begun to emerge. Then another computer arrived like a spring thunderstorm, drawing whole gardens of hobbyists up across the country and casting the efforts of the likes of Jonthan Titus and Hal Singer in the shade. It, too, came as a response to the arrival of the Mark-8, by a rival publication in search of a blockbuster cover story of their own.

Altair Arrives

Art Salsberg and Les Solomon, editors at Popular Electronics, were not oblivious to the trends in the hobby, and had been on the lookout for a home computer kit they could put on their cover since the appearance of the TV Typewriter in the fall of 1973. But the July 1974 Mark-8 cover story at rival Radio-Electronics threw a wrench in their plans: they had an 8008-based design of their own lined up, but couldn’t publish something that looked like a copy-cat machine. They needed something better, something to one-up the Mark-8. So, they turned to Ed Roberts. He had nothing concrete, but had pitched Solomon a promise that he could build a computer around the new, more powerful Intel 8080 processor. This pitch became Altair—named, according to legend, by Solomon’s daughter, after the destination of the Enterprise in the Star Trek episode “Amok Time”—and it set the hobby electronics world on fire when it appeared as the January 1975 Popular Electronics cover story.

Altair, it should be clear by now, was continuous with what came before: people had been dreaming of and hacking together home computers for years, and each year the process became easier and more accessible, until by 1974 any electronics hobbyist could order a kit or parts for a basic home computer for around $500. What set the Altair apart, what made it special, was the sheer amount of power it offered for the price, compared to the SCELBI-8H and Mark-8. The Altair’s value proposition poured gasoline onto smoldering embers, it was an accelerant that transformed a slowly expanding hobby community into a rapidly expanding industry.

The Altair’s surprising power derived ultimately from the nerve of MITS founder Ed Roberts. Roberts, like so many of his fellow electronics hobbyists, had developed an early passion for radio technology that was honed into a professional skill by technical training in the U.S. armed forces—the Air Force, in Roberts’ case. He founded Micro Instrumentation and Telemetry Systems (MITS) in Albuquerque with fellow Air Force officer Forrest Mims to sell electronic telemetry modules for model rockets. A crossover hobby-entrepreneur business, this straddled two hobby interests of the founders, but did not prove very profitable. A pivot in 1971 to sell low-cost kits to satiate the booming demand for pocket calculators, on the other hand, proved very successful—until it wasn’t. By 1974 the big semiconductor firms had vertically integrated and driven most of the small calculator makers out of business.

For Roberts, the growing hobby interest in home computers offered a chance to save a dying MITS, and he was willing to bet the company on that chance. Though already $300,000 in debt, he secured a loan of $65,000 from a trusting local banker in Albuquerque, in September 1974. With that money, he negotiated a steep volume discount from Intel by offering to buy a large quantity of “ding-and-dent” 8080 processors with cosmetic damage. Though the 8080 listed for $360, MITS got them for $75 each. So, while Wadsworth at SCELBI (and builders assembling their own Mark-8s) were paying $120 for 8008 processors, MITS was paying nearly half that for a far better processor.[12]

It is hard to overstate what a substantial leap forward in capabilities the 8080 represented: it ran much faster than the 8008, integrated more capabilities into a single chip (for which the 8008 required several auxiliary chips), could support four times as much memory, and had a much more flexible 40-pin interface (versus the 18 pins on the 8008). The 8080 also referenced a program stack an external memory, while the 8008 had a strictly size-limited on-CPU stack, which limited the software that could be written for it. The 8080 represented such a large leap forward that, until 1981, essentially the entire personal and home computer industry ran on the 8080 and two similar designs: the Zilog Z80 (a processor that was software-compatible with the 8080 but ran at higher speeds), and the MOS Technology 6502 (a budget chip with roughly the same capabilities as the 8080).[13]

The release of the Altair kit at a total price of $395 instantly made the 8008-based computers irrelevant. Nat Wadsworth of SCELBI reported that he was “devastated by appearance of Altair,” and “couldn’t understand how it could sell at that price.” Not only was the price right, the Altair also looked more like a minicomputer than anything before it. To be sure, it came standard with a measly 256 bytes of memory and the same “switches and lights” interface as the ancient kits from 1971. It would take quite a lot of additional money and effort to turn into a fully functional computer system. But it came full of promise, in a real case with an extensible card slot system for adding additional memory and input/output controllers. It was by far the closest thing to a PDP-8 that had ever existed at a hobbyist price point—just as the Popular Electronics cover claimed: “World’s First Minicomputer Kit to Rival Commercial Models.” It made the dream of the home computer, long cherished by thousands of computer lovers, seem not merely imminent, but immanent: the digital divine made manifest. And this is why the arrival of the MITS Altair, not of the Kenbak-I or the SCELBI-8H, is remembered as the founding event of the personal computer industry.[14]

All that said, even a tricked-out Altair was hardly useful, in an economic sense. If pocket calculators began as a tool for business people, and then became so cheap that people bought them as a toy, the personal computer began as something so expensive and incapable that only people who enjoyed them as a toy would buy them. Next time, we will look at the first years of the personal computer industry: a time when the hobby computer producers briefly flourished and then wilted, mostly replaced and outcompeted by larger, more “serious” firms. But a time when the culture of the typical computer user remained very much a culture of play.

Appendix: Micral N, The First Useful Microcomputer

There is another machine sometimes cited as the first personal computer: the Micral N. Much like Nat Wadsworth, French engineer François Gernelle was smitten with the possibilities opened up by the Intel 8008 microprocessor, but could not convince his employer, Intertechnique, to use it in their products. So, he joined other Intertechnique defectors to form Réalisation d’Études Électroniques (R2E), and began pursuing some of their erstwhile company’s clients.

In December 1972, R2E signed an agreement with one of those clients, the Institut National de la Recherche Agronomique (INRA, a government agronomical research center), to deliver a process control computer for their labs at fraction of the price of a PDP-8. Gernelle and his coworkers toiled through the winter in a basement in the Paris suburb of Châtenay-Malabry to deliver a finished system in April 1973, based on the 8008 chip and offered at a base price of 8,500 francs, about $2,000 in 1973 dollars (one fifth the going rate for a PDP-8).[15]

The Micral N was a useful computer, not a toy or a plaything. It was not marketed and sold to hobbyists, but to organizations in need of a real-time controller. That is to say, it served the same role in the lab or factory floor that minicomputers had served for the previous decade. It can certainly be called a microcomputer by dint of its hardware. But the Altair lineage stands out because it changed how computers were used and by whom; the microprocessor happened to make that economically possible, but it did not automatically make every machine into which it was placed a personal computer.

Useful personal computers would come, in time. But the demand that existed for a computer in one’s own home or office in the mid-1970s came from enthusiasts with a desire to tinker and play on a computer, not to get serious business done on one. No one had yet written and published the productivity software that would even make a serious home or office computer conceivable. Moreover, it was still far too expensive and difficult to assemble a comprehensive office computer system (with a display, ample memory, and external mass storage for saving files) to attract people who didn’t already love working on computers for their own sake.

Until these circumstances  changed, which would take several years, play reigned unchallenged among home computer users. The Micral N is an interesting piece of history, but it is an instructive contrast with the story of the personal computer, not a part of it.