In 1974, a major semiconductor company released its first 8-bit CPU that was good enough to build a serious computer around. In 1975, a smaller company built a computer around it, a horizontal box with backplane and expansion cards, released it as a kit for ~$400 or fully assembled for somewhat more.

The CPU was the 8080, the computer was the Altair 8800, and it took off, inspiring IMSAI, CP/M, and a whole ecosystem of business computing in the late seventies that was sufficiently comprehensive that the Apple II even acquired an expansion card with a Z80 just so that it could run CP/M.

The CPU was the 6800, the computer was the SWTPC 6800 Computer System, and it... I won't say sank without a trace. Surely they sold some units. But it failed to be very popular or influential, to the extent that, though I've done a lot of reading about the history of computing in the last few years, its existence never really registered with me until today.

One can imagine an alternative history in which it was the 6800 that took off in a big way, leading to a future history where the dominant operating system for business computing ran on the 6502. I don't know if that would've been better or worse, but it would certainly have been different.

Why did it not happen?

The 8080 was technically superior to the 6800 in both performance and code density. Did either hobbyists or businesses, at that time, know enough about the respective CPUs to make their decision on that basis? I kind of feel they didn't, though I could be wrong.

The nominal minimum price turns out to have been close to the same, with the SWTPC being slightly cheaper: Why was the SWTPC 6800 Computer System cheaper than the Altair?

The SWTPC didn't come with a front panel with switches and blinking lights; you really needed a keyboard, screen and cassette interface to do anything with it, which made the effective minimum price much higher. That would have been an issue for hobbyists. Was it an issue for businesses? Or was the chain of events that hobbyists bought the Altair, developed other products for it, leading to a scenario where the Altair had a more attractive ecosystem?

Are there any other factors I am missing, that caused the SWTPC to lose out to the Altair in the race to become the industry standard platform?

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    BTW, there are plenty of cases where a technically superior solution didn't "take off". It's generally impossible to say why.
    – dirkt
    Nov 12, 2020 at 5:02
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    But sometimes we can say why. Beta versus VHS, partly it was corporate politics, but partly it was the fact that while Beta couldn't freeze-frame without flicker, and the picture quality was not quite as good, it could store a longer show on a tape, and that turned out to matter more. So the real story is a lot more interesting than just 'marketing'.
    – rwallace
    Nov 12, 2020 at 6:35
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    @manassehkatz-Moving 2 Codidact the technical superiority of beta over VHS is a myth. Check technology connections series on youtube, he makes a much better case than me showing that beta had some drawbacks that explain by themselves why VHS was better. youtube.com/results?search_query=technology+connections+betamax Nov 12, 2020 at 9:26
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    @rwallace If that would be the case, then Video2000 would have made the race. After all, it had all the qualities you mention: Better signal (picture) than Beta/VHS, longer duration (4 hours, later up to 8, 16 with lower quality on one cassette) and could of course flicker free freeze. So I'd say as well, as soon as a product meets basic requirements it's 90% marketing and 10% luck. No tech involved - no matter how much we would like to see it that way.
    – Raffzahn
    Nov 12, 2020 at 10:52
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    I remember the SWTPC, it seemed like a sweet little machine. But by the time it came out, you didn't buy a machine for itself, you bought it for the hardware and software universe that it was part of. And the SWTPC stood alone. The 6502 was not the heir to the 6800 in your alternate universe, that would have fell to the 6809 or 68000. Nov 15, 2020 at 6:13

2 Answers 2



SWTPC and their 6800 system did sell quite well and over a longer time than all of its competition. The question is rather why do most people only know MITS/Altair, which I'd say is rather a hype in hindsight - plus the same effect that made the PC ubiquitous: Cloning.

The Long Run

When considering 'success' of a single machine or manufacturer it is worth to keep in mind that essential all manufacturers that played a major role during 1976 to 1979 faded rather soon or went belly up straight away. So the success was rather limited.

Lets take a look at major player of the first wave:

  • MITS - Sold to TA in 1979, S100 business ended.
  • IMSAI - Bankrupt in 1979.
  • OSI - Sold in 1981, changed business.
  • Digital Group - Folded in 1979 (with a closet full of cheques :).
  • SWTPC - Made systems until a decade later (1989)!

All of them left, one way or another, the end customer business by around 1980 - all except SWTPC who stayed until way into the 1980s. So not so sure if the SWTPC 6800 can be seen as a failure due company, pricing or alike. Sales wise all these companies were quite comparable. So beside management failure - and there was quite some - a changed market environment put a stop on them - with none being able to take the turn.

While making boxes with minimalist computers was a great idea in ~1975, and making them extendable should have made them future proof, it was the all in one, ready to use systems that came after, who took over. Starting with Processor Technology's SOL and the mighty three (Apple II, TRS-80, Commodore PET), ready to use computers were available. All in one and atop your desk. Why buying a bulky box plus a terminal when one can get all in one and at a lower price with better performance?

All of the above tried to get into that market, like

  • Digital Group's Bytemaster - almost a predecessor of schleptops to come, or
  • IMSAI's VDP-80 - looks like a Tandy clone

But most failed - maybe with an exception of OSI with their Superboard/Challenger series.

So if MITS failed, why did S100 survive? Cloning it was. With IMSAI being the first and many more to come. The same reason the Apple II had its long enduring success and later the PC. Others were building compatible machines and compatible add ons that enabled an ecosystem independent of the original manufacturer.

S100 played an even more unique role here, as it allowed the construction of upper end micro computers from (mostly) standard parts. THey could be equipped with faster CPUs and lots of memory, capable to run (comparable) large applications and even multi user environments - filling a niche right below and up to classic mini computers. This gave an extension in life way past the due date of other systems.

Heck, In all the years, I have never found an Altair or IMSAI with the original CPU still installed. All had some kind of Z80 all in one CPU board or even better.

On a final note, as the question tries to frame a lets competition between CPUs, let's be serious, the CPU used wasn't really a deciding factor at all. Not back then and not now - except maybe for some very special reasoning - or plain nerdyness. It's price and usability.

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    Good points, thanks! Though to be clear on the last paragraph: as I said, I agree with you that the technical merit of one CPU versus the other was probably not really a deciding factor.
    – rwallace
    Nov 12, 2020 at 14:28
  • "essential all manufacturers that played a major role during 1976 to 1979 faded rather soon or went belly up straight away" -- Apple seems to be doing rather well, and Commodore had a good run in the 80s before succumbing to its own mismanagement. Change that timeframe to, say, 1975-77 and I agree; but one of the reasons they faded was the rise of the PET, the Apple II, and the TRS-80. Nov 12, 2020 at 19:35
  • @MichaelGraf Mind to read at whole before commenting? Like until where I mentioned the changing landscape? I assume you're aware that neither of the 'new kids' really did put down a foot before 1979? They only became major players around that time. Real live loves smooth transitions.
    – Raffzahn
    Nov 12, 2020 at 19:51

I strongly suspect CP/M was the key. Plenty of 8080 (and by extension, Z80) machines ran other operating systems, particularly the Radio Shack TRS-80 line. But the basics of Altair, Imsai, Osborne, Kaypro, NorthStar and so many others promoted the Intel 8080/compatible market in a huge way. CP/M led to mass-market business software like WordStar, dBase II, and many other programs.

CP/M was no miracle operating system. But it was early - 1974. The (from a brief look) somewhat comparable FLEX for 6800 came out in 1976. Two years was a long time even in those days, which could have easily affected early adoption of 8080 vs. 6800.

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    I would think that manufacturers that came in the 1980s like Osborne or Kaypro may have played a little role in what happened during the 70s.
    – Raffzahn
    Nov 12, 2020 at 11:14
  • Osborne and Kaypro weren't the best choices, just what came to mind while writing - they were at the tail end of CPM. Nov 12, 2020 at 14:58

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