I am not a huge fan of the IBM PC. For one, it was a mediocre design. Most important, it caused a mass extinction in the small computer space so that, even today, the majority of desktop computers out there are distant descendants of the original 5150. They probably have a complete 5150 inside them, just for compatibility with ancient software.
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What the IBM PC provided was a standard on which competition was unleashed and massive investments went into improving a common platform. Which is how all the closed proprietary alternatives got overwhelmed. Without it, we would have many weak walled gardens incompatible with each other, like we have on the smartphone market.
Listen to Linus Torvalds when he says that the PC is so easy compared to the nightmare of all those incompatible arm SOCs.
I dream of a smartphone PC.
> What the IBM PC provided was a standard on which competition was unleashed
Entirely accidental. What really started this was the reverse engineering of the BIOS. This allowed any company to enter the market with a PC-compatible computer. IBM tried, but clean-room proved to be an effective defense.
> Without it, we would have many weak walled gardens
Kind of. There were Apple II clones with varyingly clever schemes around copying the original ROMs, and it provided slots so many manufacturers could provide hardware for the machines. Microsoft was one of them, with a Z-80 card that allowed the II to run CP/M software. Atari had a serial bus that allowed external expansion - less popular than the II, but still allowed other manufacturers to expand it. And let's not forget the ubiquitous S-100 bus, with hundreds of different companies making hardware for. In 1983 you could assemble a computer around your choice of processor, graphics (or not), IO, mass-storage, and so on.
> incompatible with each other
Kind of. Prior to MS-DOS, CP/M was the de-facto 8-bit standard for business computers. It had a multi-user version called MP/M, and versions for processors other than the 8080/85 and Z-80. In the higher end, Unix-compatible small computers started to appear - the TRS-80 model II could get a 68000 board, for instance.
> There were Apple II clones with varyingly clever schemes around copying the original ROMs, and it provided slots so many manufacturers could provide hardware for the machines.
It looks like the vast majority of clones used a (near bit-by-bit) copy of the original ROMs. I've only heard of one company using licensed ROMs and one company using reverse engineered ROMs in the American market.
> And let's not forget the ubiquitous S-100 bus, with hundreds of different companies making hardware for. In 1983 you could assemble a computer around your choice of processor, graphics (or not), IO, mass-storage, and so on.
These machines, in conjunction with CP/M, were the closest thing to what the IBM compatible would become, in terms of it being an open platform. Unfortunately, they were also notorious for being incompatible with each other. As you noted, they didn't have to use even remotely similar processors. Heck, you couldn't even exchange disks between many variants (the format was incompatible).
> Entirely accidental. What really started this was the reverse engineering of the BIOS.
Not really. IBM didn't intend the clones, but the effort to create clones was intentional. Not only did you have the outright rip-offs and famously cleanroom reverse engineered ROMs, but you had many companies making machines with various levels of compatibility while trying be legal. Once the PS/2 arrived, IBM's attempt to regain control of the platform, there was a concerted effort by their competitors to ensure they (rather than IBM) defined the standard.
The biggest and most catastrophic effect of the PC was to delay mainstream multi-user systems and graphic UIs by five to ten years. The standardisation was a game changer, but both the hardware and OS were brain damaged compared to what could easily have been possible.
Atari ultimately won. USB was designed by the same people who did Atari's serial bus using lessons learned, and thus is a direct descendant. Meanwhile most competes don't have slots, though high end will have a few.
There was an industry standard before IBM PC, based on Z80 S100 and CP/M
It was a mediocre design, but it came with superb documentation for every bit of hardware and software in it, including the source code for its BIOS and all the hardware details of the peripheral and expansion interfaces.
I wish this had remained true for its descendants.
"…but it came with superb documentation for every bit of hardware and software in it,…"
Very true, I still have my XT and AT manuals and use them as illustrations of how documentation should be done. Back then, good documentation included both operational and service manuals including maintenance and circuit diagrams (and as you say IBM even included BIOS source code).
IBM documentation up until at least that point had always been suburb across its product range. For example I have the original copy of this IBM typewriter manual even though I've no longer the machine because the manual is so very excellent:
https://archive.org/details/bitsavers_ibmtypewriricTypewrite...
Manufacturers considered their products and manuals proprietary and protected them with patents and copyrights but they were not secret as is so often the case nowadays. Right to Repair wasn't even a concept back then, had anyone suggested such a notion they'd be laughed at, as it was automatically assumed. What counts as documentation nowadays is an utter disgrace.
IBM was not alone, companies such as HP, Tektronix, Racal (and many others) also produced truly excellent documentation—especially so their maintenance and repair manuals. Equipment performance could often be judged on the quality of the manuals alone.
Most are paying less than a fifth of the cost for a PC nowadays, inflation adjusted, compared to 1981.
Those paying equivalent prices or higher for a mid spec computer do get much higher quality documentation, such as high end Toughbooks.
Some of it did. They are still mediocre ;-)