This is how computer history changed forever

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IBM was the owner and lord of bits and bytes in the early 1980s. At that time, Apple, Microsoft and the manufacturers of those legendary 8-bit computers also stood out, but it didn’t matter: the blue giant dominated technology with a firm hand. business computing, and to show a button: the PC was not called a PC. It was called IBM PC.

Those responsible for that company had us all well tied, and they did it with a most effective technique: although they published a good part of the source code of the operating system that governed those antediluvian PCs, what they did not allow to replicate was the BIOS code , that system that allowed them to be the only ones to be able to offer their PCs. And then Phoenix Technologies arrived to change the world -our world- with a much less obscure technique than it might seem: reverse engineering.

the clean room

Bernard A. Galler told the story of that milestone years ago in ‘Software and Intellectual Property Protection’, a book in which he recounted how IBM was happy and ate partridges when control its ecosystem in such an efficient way.

No one could cough them up, but also the developers knew there was a lot of dough in that segment, so they readily accepted IBM’s terms. Does anyone know the philosophy (cough, Apple, cough cough)?

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In his book Galler explained how some manufacturers tried on certain occasions to market clone PCs with copies of their BIOS, and IBM stopped them based on legal demands. That’s where Phoenix Technologies took advantage of the concept known as “clean room” either ‘clean room‘ (also known as “chinese wall“) to try to replicate that important subsystem.

As explained in ComputerWorld years laterat Phoenix Technologies established two groups of engineers very distinct and completely separate visually.


The first group of engineers studied the IBM BIOS, whose code was about 8 KB, and they described everything that this subsystem was doing without making references to the code as such. They simply told the members of the second group of engineers how the BIOS behaved step by step.

The big winner? microsoft

From those functional instructions, the second group had an equally critical mission: try to replicate what that subsystem did, but programming it from scratch and not being able to copy a single line of code from the IBM BIOS because they literally had no direct access to it.


The result was incredible: managed to perfectly replicate the IBM BIOS -even with some unintentional coincidences in the code- and that was the trigger for the industry to access an alternative to that restrictive code.

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The clone PC was born, and IBM lost control of the hardware. Who was the great winner of that story? It wasn’t IBM, of course.but neither was Phoenix Technologies.

It was microsoft.

The appearance of clone PCs allowed their operating systems -first MS-DOS, then Windows- will end up being the de facto standard for a segment that grew like foam thanks to a reverse engineering solution that few ended up knowing about.


Phoenix was not the only one to have that idea: in Compaq precisely used that concept of “clean room” two years earlier and ended up being able to create what was known as the first “100% IBM compatible PC, the Compaq Portable, which would become a brutal sales success.

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Of course, Compaq also kept that BIOS for its own PCs and laptops. AMI was another of the companies that copied the Phoenix Technologies model, and dozens (hundreds?) of manufacturers ended up licensing those BIOSes to be able to offer their equipment throughout the world.

The impact was also felt in other areas

That achievement would be dramatized many years later in an episode of the series ‘Halt and Catch Fire‘, an AMC production that, among other things, recreated the genesis of that clone PC business model that ended IBM’s stranglehold (expressly mentioned in the series, although other names were fictitious).

as they indicate on WikipediaIBM ended up acknowledging that could not sue Phoenix Technologies by that approach to the problemand that worked for a large number of manufacturers who took advantage of that option.

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Others were not so lucky, and manufacturers such as Corona Data Systems, Eagle Computer and Handwell Corporation were sued and forced to pay large sums for violating the copyright of the IBM BIOS, a company that in at least in this case behaved effectively like a ‘patent troll more, taking money from patents that made free competition very difficult.

At IBM, in fact, they continued to take advantage of that model, because even years later, in the early 1990s, they kept closing million dollar deals on the same subject: manufacturers such as Panasonic and Kyocera had replicated the BIOS without that Phoenix Technologies approach, something that would be very expensive in hindsight. It didn’t matter, of course: the world had already changed, and the tricks up their sleeves were no longer IBM, but Microsoft.

But that, of course, is another story.

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IBM was the owner and lord of bits and bytes in the early 1980s. At that time, Apple, Microsoft and…

IBM was the owner and lord of bits and bytes in the early 1980s. At that time, Apple, Microsoft and…

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