Xjyuk

The IBM PC was cloned very early on, and many third parties made hardware peripherals. This required users to run an OS, install drivers, manage IRQs and hardware bus addresses, etc. Why was this a strength of the platform, instead of a weakness?

I'm thinking specifically of Commodore/Amiga where the hardware was less diverse and end users/programs didn't need to manage so much fragmentation. I'm also thinking of modern examples like Android where fragmentation is a big problem, and iOS where the hardware is less diverse and that is seen as an asset of the platform in ways.

Inspired by Why weren't bootable game disks ever common on the IBM PC?

Unlike the Amiga, the IBM PC was always seen as mainly a business computer. Having business done on lots of small machines on desks, rather than on large central machines via terminals, meant that businesses had to provide support staff to configure machines and assist users, rather than having staff to look after the central machines.

However, the total cost of ownership would seem to have been lower, judging by the runaway success of PC-based business computing. PCs also became less demanding to configure over time, as they came with more and more built-in capability.

Hardware diversification also provided ways for PC manufacturers to compete, driving costs down and ease-of-use up. However, they always remained PC-compatible, which meant they could run the same application software.

The fragmentation of Android, in my experience, has been caused by the fragmentation of the ARM 32-bit instruction set, which was a consequence of ARM's willingness to customise their processor designs for their hardware-manufacturer customers, and those hardware manufacturers' lack of appreciation for the benefits of application compatibility. It's just the same situation as you'd get if Dell and HP Windows machines had different instruction sets, custom-designed for Dell and HP by Intel. As a chip manufacturer, wanting the benefits of making millions of identical chips, Intel don't do that. ARM discarded the idea with ARMv8, which does not get customised by individual customers, curing the fragmentation problem.

The IBM PC was cloned very early on, and many third parties made
hardware peripherals. This required users to run an OS, install
drivers, manage IRQs and hardware bus addresses, etc. Why was this a
strength of the platform, instead of a weakness?

A wide range of hardware devices was a strength, in that, if IBM wasn't willing to build it, or was unable to build it and release it in a timely manner, then someone else (perhaps many someone elses) could. This broadens the range of use for the platform as a whole. That makes for a virtuous cycle: greater range, more users, more incentive to support the system.

Dealing with the hardware configuration was a downside of the variety, sure, but apparently not a sufficient disincentive.

(The PDP-11 followed a similar arc, especially in its early days, where the documented bus architecture allowed a robust add-on marketplace to develop).

One problem in designing future-proof systems is deciding what features of the system's present design should be regarded as fundamental and what aspects should be considered happenstance. If some features of a design get treated as fundamental, it will be very difficult to change them later, but features needed to accomplish tasks efficiently can't be relied upon, it will be impossible to accomplish those tasks reliably and efficiently.

Some aspects of the PC's design (e.g. the presence of CGA display memory at hardware address 0xB8000) ended up being treated as fundamental because IBM and Microsoft failed to provide a reasonable alternative, even though it would have been better to avoid such dependance (e.g. by providing a function to inquire where display memory is located). For the most part, though, the PC ended up with a relatively practical mix of fundamental and happenstance design elements.

It was an advantage because the IBM PC became an extensible computing platform. The most popular competitor to it previously was the Apple II, another open platform.

The PC, as a platform, was popular to users because of the choices it enabled, as developers because of the foundations that it laid, and engineering firms because they could focus on what they wanted to do (say, a graphic card, or a computer vision system) rather than an entire computing system.

Since MS-DOS availed the ability to readily install things like drivers, the platform allowed things like configurable interrupts, etc. it gave everyone involved a lot of flexibility in designing their solutions.

So, not only was the hardware "open" (the PC bus system was reasonably well documented), the software was also "open" (in that it was straight forward to augment the system with your own drivers). I don't mean "open" as it's typically referred to today (i.e. free, source code available, etc.) but it was "open" in the sense that anyone could make a card, with no payment to IBM, and anyone could make a driver, with no payment to Microsoft. You also, as an end user, didn't have to rebuild the operating system software yourself like you did in CP/M. CP/Ms design wasn't as flexible in this regard as MS-DOS was. (This changed a little later, but the legacy lived on.)

Yes, this lead to complexity at the user level since the burden of configuring the cornucopia of diverse systems fell on them. It also lead to some complexity at the software development level - but only at the edge cases. In time things became common and compatible, lowering the barrier for software.

So, since the PC offered a unique combination at the time of a robust foundation, especially once the XT hit, of the BIOS, large memory space, the large array of peripherals (robust character graphics, nice hi res graphics, color graphics, floppies, hard drives, printers, serial ports) and then the "infinite" expandability of an open bus and extensible base operating system, and then the explosion of the clones, the network effect surrounding the PC became very compelling despite all of its innate weaknesses.

The PC represented a maturity of the product and the industry after learning from the rise and struggles of the diverse early micro environment where everything was cordoned off to a limited platform.

The hardware in PC clones was not particularly diverse, if the technical characteristics of the hardware is the distinguishing factor. Yes, there was a great diversity of manufacturers and vendors, but the diversity of features was pretty minimal. It is probably best to describe the PC clones of the 1980s as vanilla computers. And this was their real strength.

Because the hardware was "PC compatible", having the basic features required to make it so, it could be counted on to run the popular MS-DOS applications of the time. This actually liberated the user from having to think very much about the diversity of vendors. Most buyers of PC clones at the time weren't venturing into esoteric hardware for highly specific use-cases, nor were they buying components and assembling a properly configured PC themselves. They just wanted a machine to run Wordperfect, Lotus 1-2-3, dBase III, and other popular business titles. Therefore, their buying decision was generally driven by the price-to-performance ratio, and the performance was mainly a matter of CPU (e.g. 8088 vs. 80286 vs. 80386) and clock speed. This allowed for fairly simple buyer comparisons.

So, the diversity of vendors created little real hassle for buyers (they always got the same basic features and compatibility), while also fostering a highly-competitive market where price/performance ratio fell rapidly. It was the rapidity of falling prices with rising performance that allowed the PC clones to overwhelm the competition from Apple, Commodore, etc.

First, having the plans available allowed small companies to build their own IBM PC clones. You didn't have to be a monolithic company like IBM to build one. A modern analogy is that you don't have to be Google to design an Android phone.

Second, each of these numerous little companies did their own marketing, greatly expanding the platform's visibility in the marketplace.

Third, these companies often shared technology, reducing development and manufacturing costs through economies of scale. Chipsets, CPUs, BIOS firmware, etc.